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i. Abstract

This OGC Land and Infrastructure Conceptual Model Standard presents the implementation-independent concepts supporting land and civil engineering infrastructure facilities.  Conceptual model subject areas include facilities, projects, alignment, road, rail, survey, land features, land division, and wet infrastructure (storm drainage, wastewater, and water distribution systems).  The initial release of this standard includes all of these subject areas except wet infrastructure, which is anticipated to be released as a future extension.

This standard assumes the reader has a basic understanding of surveying and civil engineering concepts.

ii.  Keywords

The following are keywords to be used by search engines and document catalogues.

OGC document, LandInfra, Infra, infrastructure, civil, survey, land parcel, land feature, terrain, road, rail, alignment

iii.  Preface

After reviewing the existing LandXML format [1], the participants involved decided [2] that a new standard based on a subset of LandXML functionality was desired.  Further, this new work activity would be use case driven, consistent with the OGC standards baseline, implemented with GML, and supported by a UML conceptual model.  Called InfraGML, this new standard would:

The following steps for the new standards activity included:

  1. Subject area identification:  The list of initial subject areas for InfraGML were identified.  Additionally, other areas may be identified as possible future extensions.
  2. Use case definition:  Use cases relevant to each subject area were identified and described.  This was harmonized with the bSI Alignment Project use cases, the building SMART Alliance (bSA) BIM-GIS use case list, and any forthcoming use case definitions from the ISO TC211 GIS-BIM ad hoc committee.
  3. Conceptual modeling:  A UML Conceptual Model of the initial subject areas was developed, including defining Core functionality.  This model was harmonized with the model developed by the bSI Alignment Project.
  4. RFC:  Prior to any GML encoding, a public Request for Comment was issued based upon the UML conceptual model [3].  This RFC requested input from the existing LandXML community (and others), including users as well as software developers. The conceptual model would then be revised accordingly.
  5. GML encoding:  A GML 3.2.1 / 3.3 compatible standard was then to be developed based on the revised UML conceptual model.
  6. Extensions:  Similar steps would be followed for subsequent subject areas.

This OGC document provides the revised UML Conceptual Model from step 4 above.  In accordance with the use cases, this model standardizes a single set of consistent, implementation-independent concepts for the identified subject areas.  The subject areas can be implemented in any potential implementation-specific standards such as InfraGML.  The Land and Infrastructure Domain Working Group (DWG) and Standards Working Group (SWG) agreed that the implementation-independent Conceptual Model should first be adopted by the OGC. To ensure harmony among other OGC Standards and across other possible Infra implementations the approval should be prior to the creation of the InfraGML implementation standard.

The alignment subject area use cases and conceptual model were developed jointly with the buildingSMART International (bSI) Infrastructure Room IfcAlignment project [4] team to insure compatibility between the anticipated GML and IFC standards.  Joint work continues to ensure compatibility with future bSI infrastructure projects such as IfcRoad.

Future extensions to this Land and Infrastructure Conceptual Model Standard that will address wet infrastructure are anticipated.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights.

Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.

iv.  Submitting organizations

The following organizations submitted this Document to the Open Geospatial Consortium (OGC):

Bentley Systems, Inc.
Leica Geosystems
Aalborg University, Dept. of Development & Planning
Swedish Transport Administration
Vianova Systems AS

v.  Submitters

All questions regarding this submission should be directed to the editor or the submitters:


Name Affiliation OGC Member?

Paul Scarponcini, SWG chair

Bentley Systems, Inc.


Hans-Christoph Gruler, SWG co-chair

Leica Geosystems


Erik Stubkjær

Aalborg University, Dept. of Development & Planning


Peter Axelsson

Swedish Transport Administration


Leif Granholm



Johnny Jensen

Vianova Systems AS


Thomas Liebich

buildingSMART International


Orest Halustchak



1.    Scope

The scope of the Land and Infrastructure Conceptual Model is land and civil engineering infrastructure facilities.  Anticipated subject areas include facilities, projects, alignment, road, railway, survey, land features, land division, and “wet” infrastructure (storm drainage, wastewater, and water distribution systems).  The initial release of this standard is targeted to support all of these except wet infrastructure.

Land provides the environment upon which infrastructure facilities exist.  This standard includes division of land based on administrative (jurisdictions and districts) as well as interests in land (e.g., land parcels, easements, and condominiums).  The standard also includes support for topography (terrain) as well as subsurface information.  Finally, this standard regards the surveying needed to locate infrastructure facilities on the terrain in compliance with interests in land.

Infrastructure facilities are improvements constructed and operating on land.  This standard includes support for information about civil engineered facilities, such as roads and railway and in the future, “wet” infrastructure including storm drainage, wastewater, and water distribution systems.  Though often not considered to be infrastructure, buildings are included to a limited extent.  The contributors to this standard do not anticipate that the design of utilities, such as electrical distribution, gas networks, and telecommunications will be explicitly included as facilities, though the detailed location of such facilities may at some point be added for referenceability.  However, the rough location and legal protection of such facilities are covered by this standard; see SuperficieObject and Easement, subsections of 7.10.2, InterestsInLand.  

This OGC® standard identifies concepts relevant to the identified subject areas, based upon a set of defined use cases.  It is anticipated that future OGC infrastructure standards will implement these concepts is various implementation languages, such as GML.

1.1    Relationship to Other Standards

LandXML:  This LandInfra Standard extends a subset of what is contained within LandXML 1.2 [1].  As a Conceptual Model Standard, this OGC standard defines some of the concepts which were implemented in LandXML 1.2.  For a more detailed comparison, see Annex D.1.

This standard is related to and/or consistent with the following OGC and ISO standards.

OGC Abstract Specification Topic 1 – Feature Geometry:  This LandInfra standard relies heavily upon the geometry types defined in this Abstract Specification for spatial representations.  LandInfra adds some additional geometry types not included in Topic 1.

OGC Abstract Specification Topic 2 – Spatial Referencing by Coordinates: This LandInfra Standard relies upon Topic 2 for the definition of coordinate reference systems.

OGC Abstract Specification Topic 19 – Linear Referencing:  This LandInfra Standard relies heavily upon the linear referencing types defined in this Abstract Specification for linearly referenced locations.

OGC Abstract Specification Topic 20 – Observations and Measurements: This LandInfra Standard relies upon the observation acts, their results and sampling features defined in this Abstract Specification.

ISO 19130, Imagery sensor models for geopositioning: This LandInfra Standard relies upon the sensor data parameters for imagery sensors defined in this ISO TC211 standard.

ISO 19115, Metadata: This LandInfra Standard relies upon the metadata describing geospatial imagery defined in this ISO TC211 standard.

CityGML [5]: There are some potential overlaps between this LandInfra Standard and CityGML.  Many of the FeatureTypes in LandInfra appear as CityGML CityObject subclasses such as Building (Building), Road (Road), Railway (Rail), LandSurface (ReliefFeature), LandFeature (WaterBody, VegetationObject), and AdministrativeDivision (LandUse).  The CityGML feature name is shown in parentheses.  However, the level of detail attached to these features is significantly different: CityGML focuses on Buildings whereas LandInfra focuses more on land and infrastructure facilities other than buildings.

IndoorGML [6]:  This standard regards building and building parts used for access. Identification of these parts may be supplemented with indoor connectivity graphs and used for indoor navigation in accordance with IndoorGML.  Analogous extensions to outdoor is anticipated.

ISO 19152, LADM [7]: This LandInfra Standard addresses a subset of LADM. Consistency requests motivate deviations from LADM, but compares to LADM classes.

ISO 19103, Conceptual Schema Language:  This LandInfra Standard relies heavily upon the base data types defined in this ISO TC211 standard.

ISO 19109, Rules for Application Schema:  This LandInfra Standard supports the General Feature Model as defined in this ISO TC211 standard.

bSI IfcAlignment [4]:  The Alignment conceptual model in this LandInfra Standard was developed jointly with the bSI IfcAlignment conceptual model.  The objective is that they be as similar as possible, with only minor differences due mostly to the respective environments in which these standards exist.  This consistency should enable linking of geospatial and BIM data based upon linear location.

bSI IFCs for roads and railways:  The intent is that the Road and Railway conceptual model in this LandInfra Standard be compatible with the forthcoming bSI IFC conceptual model.  So far, only the proposed Korean road model [8] and Chinese railway models have been discussed in bSI and they may become regional PAS submittals instead of international bSI standards.  Work on an international standard is commencing within bSI as IFC Roads and Railways.  LandInfra does not intent to be as detailed as IFCs presumably will, so the specification of Road and Railway elements herein should not conflict with the eventual IFC model.

2.    Conformance

This standard defines concepts for land and civil engineering infrastructure facilities.

Requirements for one standardization target type is considered:

Such encoding standards might include, for example, GML, IFC, SQL, XML, JSON, etc.

Conformance with this standard shall be checked using all the relevant tests specified in Annex A (normative) of this document. The framework, concepts, and methodology for testing, and the criteria to be achieved to claim conformance are specified in the OGC Compliance Testing Policies and Procedures and the OGC Compliance Testing web site[1].

In order to conform to this OGC® conceptual standard, a standardization target shall choose to implement the core conformance class and any of the other conformance classes with their dependencies.  Conformance classes are based on requirements classes which are specified in this standard. 

All requirements classes and conformance classes described in this document are owned by the standard(s) identified.

3.    Normative References

The following normative documents contain provisions that, through reference in this text, constitute provisions of this document. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the normative document referred to applies.

ISO 6707-1:2014, Buildings and civil engineering works — Vocabulary — Part 1: General terms
ISO 19103, Geographic information – Conceptual schema language.
ISO 19109:2015, Geographic information – Rules for application schema
ISO 19115, Geographic information – Metadata
ISO 19130, Geographic information – Imagery sensor models for geopositioning
OGC 01-101, Abstract Specification Topic 1 - Feature Geometry, (ISO 19107), May 10, 2001.
OGC 08-015r2, Abstract Specification Topic 2 – Spatial Referencing by Coordinates, (ISO 19111), April 27, 2010.
OGC 10-030, Abstract Specification Topic 19: Geographic information - Linear referencing, (ISO 19148), March 20, 2012.
OGC 10-004r3, Abstract Specification Topic 20: Observations and Measurements, November 10, 2010.

4.    Terms and Definitions

This document uses the terms defined in Sub-clause 5.3 of [OGC 06-121r8], which is based on the ISO/IEC Directives, Part 2, Rules for the structure and drafting of International Standards. In particular, the word “shall” (not “must”) is the verb form used to indicate a requirement to be strictly followed to conform to this standard.

For the purposes of this document, the following additional terms and definitions apply.

4.1    General Terms

4.1.1       assembly

set of related components attached to each other

[ISO 6707-1:2014]

4.1.2       component

distinct unit of construction or a product constructed or manufactured to serve a specific function or functions

Note 1 to entry: ISO 6707-1:2014 limits components to manufactured products

4.1.3       conceptual model

model that defines concepts of a universe of discourse

[ISO 19103, 4.11, 4.23]

4.1.4       conformance class

set of conformance test modules that must be applied to receive a single certificate of conformance

[OGC 08-131r3]

4.1.5       dataset

identifiable collection of data

[ISO 19115]

4.1.6       dimension

extent in a given direction or along a given line, or a given angle

[ISO 1803:1997, 3.1]

4.1.7       document

information in permanent form which is approved by one or more signatures

Compares to ISO 19152:2012 4.1.21 source

4.1.8       feature

abstraction of real world phenomena

[ISO 19103, 4.16]

4.1.9       gradient

ratio of difference in level between two points to the horizontal distance between them

[ISO 6707-1:2014]

4.1.10       height

vertical dimension above a horizontal reference level

[ISO 6707-1:2014]

4.1.11       height

distance of a point from a chosen reference surface measured upward along a line perpendicular to that surface

Note 1 to entry: The surface is normally used to model the surface of the Earth.

 [OGC 08-015r2]

4.1.12       length

one of two horizontal dimensions, normally the larger

Note 1 to entry: The other is width.

[ISO 6707-1:2014]

4.1.13       level

value of the vertical dimension of a point above or below a defined reference

[ISO 6707-1:2014]

4.1.14       linear element

1-dimensional object that serves as the axis along which linear referencing is performed

Note 1 to entry: Also known as curvilinear element.

EXAMPLES   Feature, such as “road”; curve geometry; directed edge topological primitive, Alignment.

[OGC 10-030]

4.1.15       party

a person or organization that plays a role in a lawful process

Compares to ISO 19152:2012 4.1.13 party

4.1.16       physical element

any component defined within the spatial and functional context of a facility

4.1.17       positioning element

virtual element used to position, align, or organize physical elements

4.1.18       product

item manufactured or processed for incorporation in construction works

[ISO 6707-1:2014]

4.1.19       professional

person, generally with tertiary education, who through a license is bound to act according to the standards of a professional association

Note 1 to entry: In common usage, the term professional includes a much broader scope of individuals.  Here, it only refers to those who are licensed, such as land surveyors.

4.1.20       requirement class

requirements class

aggregate of all requirement modules that must all be satisfied to satisfy a conformance test class

[OGC 08-131r3]

4.1.21       slope

inclination of a plane surface to the horizontal

[ISO 6707-1:2014]

4.1.22       survey mark

physical object which by its form defines a point on the surface of the Earth

4.1.23       universe of discourse

view of the real or hypothetical world that includes everything of interest

[ISO 19101:2014, 4.1.38]

4.1.24       user

organization, person, animal, or object for which a building or other construction works  is designed

[ISO 6707-1:2014]

4.1.25       width

one of two horizontal dimensions, normally the smaller

Note 1 to entry: The other is length.

[ISO 6707-1:2014]

4.2    Facility and Project Terms

4.2.1       bridge

civil engineering works that affords passage to pedestrians, animals, vehicles, and services above obstacles or between two points at a height above ground

[ISO 6707-1:2014]

4.2.2       building

construction works that has the provision of shelter for its occupants or contents as one of its main purposes, usually partially or totally enclosed and designed to stand permanently in one place

[ISO 6707-1:2014]

4.2.3       civil engineering works

construction works comprising a structure, such as a dam, bridge, road, railway, runway, utilities, pipeline, or sewerage system, or the result of operations such as dredging, earthwork, geotechnical processes, but excluding a building and its associated siteworks

Note 1 to entry: Associated siteworks are included in US civil engineering projects.

[ISO 6707-1:2014]

4.2.4       construction

assembled or complete part of construction works that results from work on-site

[ISO 6707-1:2014]

4.2.5       construction work construction

activities of forming construction works

[ISO 6707-1:2014]

4.2.6       construction works construction

everything that is constructed or results from construction operations

[ISO 6707-1:2014]

4.2.7       facility

improvements of or on the land including buildings and civil engineering works and their associated siteworks

4.2.8       retaining wall

wall that provides lateral support to the ground or that resists pressure from a mass of other material

[ISO 6707-1:2014]

4.2.9       site

area of land or water where construction work or other development is undertaken

[ISO 6707-1:2014]

4.2.10       siteworks

construction works or landscape work on land associated with, and adjacent to, civil engineering works or a building

[ISO 6707-1:2014]

4.2.11       structure

construction works having an organized combination of connected parts designed to provide some measure of rigidity

[ISO 6707-1:2014]

4.2.12       track

a small path mainly used by pedestrians

 [OGC 08-007r1 CityGML]

Note 1 to entry: This is not the definition adopted by this standard.  See instead 4.5.

4.2.13       tunnel

horizontal or sloping underground enclosed way of some length

[ISO 6707-1:2014]

4.2.14       wall

vertical construction that bounds or subdivides a space and usually fulfils a loadbearing or retaining function

[ISO 6707-1:2014]


4.3    Alignment Terms

4.3.1       alignment

linear referencing system associated to linear facilities and their constructions, such as roads, railways, and bridges, used to position elements, such as road, railway or bridge elements or other physical elements, positioned along the alignment

4.3.2       horizontal alignment

linear reference line projected onto the horizontal x/y plane in a Cartesian local engineering coordinate system


4.4    Road Terms

4.4.1       carriageway roadway

part of the road or highway constructed for use by vehicular traffic, including auxiliary traffic lanes, passing places, and lay-bys

[ISO 6707-1:2014]

4.4.2       central reserve median

area that separates the carriageways of a road with dual carriageways

[ISO 6707-1:2014]

4.4.3       cycleway bicycle path

way or separated part of a road for use only by pedal cycles

[ISO 6707-1:2014]

4.4.4       footpath

way for the use of pedestrians

[ISO 6707-1:2014]

4.4.5       footway sidewalk walkway

portion of a road reserved exclusively for pedestrians

[ISO 6707-1:2014]

4.4.6       gutter

channel for collecting and draining rainwater

Note 1 to entry: ISO 6707-1:2014 adds “from a roof”

4.4.7       hard shoulder emergency lane service lane

surfaced strip, adjacent to and abutting a carriageway, intended for use by vehicles in the event of difficulty or during obstruction of the carriageway

[ISO 6707-1:2014]

4.4.8       highway parkway freeway

way over which the public has the right to pass, this right possibly being restricted to specific classes of traffic

[ISO 6707-1:2014]

4.4.9       kerb curb

border, usually upstanding, at the edge of a carriageway, hard strip, hard shoulder, or footway

[ISO 6707-1:2014]

4.4.10       lay-by stopping lane emergency lane

part of the highway set aside for vehicles to allow them to draw out of the traffic lanes and wait for short periods

[ISO 6707-1:2014]

4.4.11       motorway interstate highway freeway parkway

limited access road with dual carriageways that is not crossed on the same level by other traffic lanes, for the exclusive use of certain classes of motor vehicles

[ISO 6707-1:2014]

4.4.12       pavement

road, runway, or similar construction above the subgrade

[ISO 6707-1:2014]

4.4.13       road

way mainly for vehicles

[ISO 6707-1:2014]

4.4.14       road marking

line, symbol, or other mark on a road surface intended to regulate, warn, guide, or inform users

[ISO 6707-1:2014]

4.4.15       roundabout rotary

portion of a road, usually at a junction, on which traffic moves in one direction around a central element

[ISO 6707-1:2014]

4.4.16       traffic

movement of vehicles, people, or animals along a way

[ISO 6707-1:2014]

4.4.17       traffic lane

strip of carriageway intended to accommodate a single line of moving vehicles, frequently defined by road markings

[ISO 6707-1:2014]

4.4.18       vehicle restraint system guardrail barricade

structure that provides a system of containment for errant vehicles so as to limit damage or injury

[ISO 6707-1:2014]

4.4.19       verge shoulder

part of a highway alongside a carriageway and at approximately the same level, exclusive of embankment or cutting slopes

[ISO 6707-1:2014]

Note 1 to entry: It can include footways and cycleways.



4.5    Railway Terms

4.5.1       cant

The measurement of the difference in elevation between the outer rail and the inner rail.

Note 1 to entry: In curved track, it is usually designed to raise the outer rail, providing a banked turn, thus allowing trains to maneuver through the curve at higher speeds than would otherwise be possible if the surface was flat or level. It also helps a train steer around a curve, keeping the wheel flanges from pressing the rails, minimizing friction and wear.

4.5.2       gauge

spacing of the rails of a track, measured between the inner faces of the load-bearing rails

4.5.3       rail

a steel bar or continuous line of bars laid on the ground as one of a pair forming a railway track

[Oxford dictionary]

Note 1 to entry: Though this is the common usage definition, it is nonetheless included herein to clearly distinguish it from railway and track.

4.5.4       railway railroad

national or regional transport system for guided passage of wheeled vehicles on rails

[ISO 6707-1:2014]

a track made of steel rails along which trains run

[Oxford dictionary]

4.5.5       track

assembly of rails, fastenings, and support, for passage of vehicles

[ISO 6707-1:2014]


4.6    Survey Terms

4.6.1       antenna

electronic equipment to transmit and/or receive electromagnetic waves cf. electronic distance meter (4.6.3), geodetic GPS receiver (4.6.5)

[ISO 9849-1:2000]

4.6.2       digital field registration digital recording data logger

device that immediately collects, records and recalls surveying data and other information

[ISO 9849-1:2000]

4.6.3       electronic distance meter EDM instrument

electromagnetic distance meter instrument for directly measuring distances between the instrument and the sighting points, comprising a transmitter and a receiver

[ISO 9849-1:2000]

4.6.4       electronic tacheometer electronic stadia instrument electronic tachymeter total station theodolite

fitted with an electronic distance measuring device and with electronic scanning of the circles

[ISO 9849-1:2000]

4.6.5       Global Positioning System GPS

U.S. Department of Defense navigation system of high accuracy

[ISO 9849-1:2000]

4.6.6       Global Navigation Satellite System GNSS

using the GPS, GLONASS, Galileo or Beidou system

4.6.7       imagery

representation of phenomena as images produced by electronic and/or optical techniques

[ISO 19101-2:2008]

4.6.8       inclination compensator tilt compensator dual-axis compensator double-axis compensator

device which automatically eliminates the influence of any levelling errors of a measuring instrument on the measured values

[ISO 9849-1:2000]

4.6.9       level

<geodetic instrument> instrument for measuring differences in height by establishing horizontal lines of sight, comprising as main components a telescope which can be rotated on a vertical axis and a facility for levelling the line of sight

[ISO 9849-1:2000]

4.6.10       levelling staff levelling rod level rod

straight bar of metal or wood with a scale on a flat face, primarily used to measure the vertical distance between a point and the horizontal line of sight of a level (4.6.9)

[ISO 9849-1:2000]

4.6.11       measurement

set of operations having the object of determining the value of a quantity

[ISO/TS 19101-2:2008, definition 4.20]

4.6.12       observation

act of measuring or otherwise determining the value of a property

[ISO/TS 19156, definition 4.10]

4.6.13       observation procedure

Method, algorithm or instrument, or system of these which may be used in making an observation

[ISO/DIS 19156, definition 4.11]

4.6.14       observed value

A value describing a natural phenomenon, which may use one of a variety of scales including nominal, ordinal, ratio and interval. 

Note 1 to entry: The term is used regardless of whether the value is due to an instrumental observation, a subjective assignment or some other method of estimation or assignment.

 [ISO 19156:2011]

4.6.15       result observation result

An estimate of the value of some property generated by a known procedure

[ISO 19156:2011]

4.6.16       sensor

element of a measuring system that is directly affected by a phenomenon, body, or substance carrying a quantity to be measured

[ISO 19115-2]

4.6.17       sensor data

list of digital values produced by a sensor that represents estimated values of one or more observed properties of one or more features.


4.6.18       theodolite transit

instrument for measuring horizontal directions or horizontal directions and vertical angles, whose main components are the horizontal circle and the vertical circle, the telescope and additional devices for reading the graduated circles and for setting up the vertical axis

[ISO 9849-1:2000]

4.6.19       tacheometer stadia theodolite tachymeter theodolite

equipment designed for use in determining horizontal directions, distances and height differences

[ISO 9849-1:2000]



4.7    Land Feature Terms

4.7.1       cut

material excavated in bulk

[ISO 6707-1:2014]

4.7.2       cut

void that results from bulk excavation of material

[ISO 6707-1:2014]

4.7.3       earthwork

work of excavating (cut), or the raising (fill) or sloping of ground

[ISO 6707-1:2014]

4.7.4       earthworks

result of change of existing terrain

[ISO 6707-1:2014]

4.7.5       embankment

section of earthworks, often formed by cut or fill, where the finished ground level is above or below original ground level and whose length usually greatly exceeds its width

[ISO 6707-1:2014]

4.7.6       excavation

result of digging, lifting, and removing earth, fill, or other material from the ground

[ISO 6707-1:2014]

4.7.7       fill

material used for raising the level of the ground

[ISO 6707-1:2014]

4.7.8       finished ground level finished grade

level of paved area or surface of the land after improvements or earthwork

[ISO 6707-1:2014]

4.7.9       ground

soil, rock, and fill existing in place prior to the execution of construction works

[ISO 6707-1:2014]

4.7.10       ground level grade

level at the surface of the land

[ISO 6707-1:2014]

4.7.11       land

the surface of the Earth, the materials beneath, the air above and all things fixed to the soil

[ISO 19152:2012]

4.7.12       soil earth

mineral material that results from the weathering of rock or decay of vegetation

[ISO 6707-1:2014]

4.7.13       subgrade

upper part of the soil, natural or constructed, that supports the loads transmitted by the overlying structure of a road, runway, or similar hard surface

[ISO 6707-1:2014]



4.8    Land Division Terms

4.8.1       administrative division

division of state territory according to political, judicial, or executive points of view.

Note 1 to entry: May include other man-made divisions, e.g. according to permitted land use, but excludes drainage basins and other divisions derived from material of the Earth.

4.8.2       building part

floor-related part of a multi-storage building, subdivided according to management and use by a lawful process.

Compares to ISO 19152:2012 4.1.6 building unit, and to IfcSpatialElement

4.8.3       boundary

set that represents the limit of an entity

Note 1 to entry: Boundary is most commonly used in the context of geometry, where the set is a collection of points or a collection of objects that represent those points. In other arenas, the term is used metaphorically to describe the transition between an entity and the rest of its domain of discourse.

[ISO 19107:2003, 4.4; ISO 19152:2012 4.1.3]

4.8.4       condominium

concurrent ownership of real property that has been divided into private and common portions

Note 1 to entry: Condominium unit owners must be members of a mandatory owners’ association and engage in the maintenance of joint facilities according to a specified share.

4.8.5       condominium scheme

documentation of interest in land in terms of a statement concerning the building parts which make up a number of condominium units and the share of joint facilities of each condominium unit

4.8.6       condominium unit

type of property unit which consist of one or more privately owned building parts and has a share in the commonly owned joint facilitates, as specified in a condominium scheme

4.8.7       easement

accessory interest in land which advantages dominant land or other beneficiary.

4.8.8       interest in land

ownership or security towards real property

4.8.9       land

area of earth’s surface, excluding the oceans, usually marked off by natural or political boundaries, or boundaries of ownership

[ISO 6707-1:2014]

4.8.10       land

the surface of the Earth, the materials beneath, the air above and all things fixed to the soil

[ISO 19152:2012]

4.8.11       land parcel

contiguous part of the surface of the Earth (land and/or water) as specified through lawful process

4.8.12       liminal spatial unit

spatial unit on the threshold between 2D and 3D representations

[ISO 19152:2012]

4.8.13       ownership (in land)

includes the right to grant a lease, an easement, or a security interest and other lesser rights

Note 1 to entry: Ownership in land includes buildings and fixture on the land parcel, unless lawful process is performed in terms of establishment of condominium units.

4.8.14       spatial unit

contiguous geometrical entity, which is delimited and located on or close to the surface of the Earth through the bounding elements of its boundary.

Compares to ISO 19152:2012 4.1.23 spatial unit

4.8.15       statement

document used in lawful process

Examples include account, agreement, declaration, observation, and record

4.8.16       strata title*

title to land that is not necessarily divided horizontally, such as in high-rise buildings or for mining rights.



4.8.17       survey monument

physical object which by its form defines a point on the surface of the Earth, which is stably located, and which is recorded in a statement.

Note 1 to entry: may carry a symbol of authority, which communicates its purpose


4.9    “Wet” Infrastructure Terms

4.9.1       canel

channel constructed to carry water, usually for navigation, but which can also be used for water power, irrigation, collecting rainwater run-off, or drainage of surface water

[ISO 6707-1:2014]

4.9.2       channel

open passage for conveying or containing water

[ISO 6707-1:2014]

4.9.3       conduit

pipe, channel, or tunnel used for conveying liquids or containing electric wires or cables

[ISO 6707-1:2014]

4.9.4       culvert

transverse drain or waterway structure under a road, railway, or canal, or through an embankment, in the form of a large pipe or enclosed channel

[ISO 6707-1:2014]

4.9.5       dam

barrier constructed to retain water in order to raise its level, form a reservoir, or reduce or prevent flooding

[ISO 6707-1:2014]

4.9.6       drain

conduit, usually underground, or channel which conveys wastewater, surface water, or other unwanted liquids

[ISO 6707-1:2014]

4.9.7       drainage

removal of surplus water

[ISO 6707-1:2014]

Note 1 to entry: In this standard, drainageshall refer only to surface water.

4.9.8       drainage basin watershed

area from which all precipitation flows to a single point at a lower elevation

4.9.9       drainage system

system of drains and ancillary works that conveys their contents to a cesspool, sewerage system, outfall, or other place of disposal

[ISO 6707-1:2014]

Note 1 to entry: In this standard, drainage system shall be used to denote drainage of surface water only.

4.9.10       sland drainage*

system of conduits, structures, and embankments required to control water levels and to protect urban and agricultural land from flooding by either fresh or salt water, or to alleviate such flooding

[ISO 6707-1:2014]

4.9.11       manhole

opening fitted with a removable cover, which permits entry of a person to a pipeline or closed vessel

[ISO 6707-1:2014]

4.9.12       pipe

circular tube through which fluid can flow

[ISO 6707-1:2014]

4.9.13       pipeline

long continuous line of pipes, including ancillary equipment, used for transporting liquids or gases

[ISO 6707-1:2014]

4.9.14       service

system for conveying water, gas, warm air, or electricity, or that provides water, gas, oil, or air to or within a construction works or removes waste from it

[ISO 6707-1:2014]

4.9.15       sewer

pipeline or other construction, usually underground, which conveys unwanted liquids

[ISO 6707-1:2014]

4.9.16       sewerage system sewage system

system of sewers and ancillary works that conveys the contents to a sewage treatment works or other place of disposal

[ISO 6707-1:2014]

4.9.17       surface water

water that flows over, rests on, or drains from the surface of buildings, other structures, or the ground

[ISO 6707-1:2014]

4.9.18       tube pipe

hollow product, usually formed by a continuous process to a definite cross-section, which is small in relation to its length

[ISO 6707-1:2014]

4.9.19       wastewater sewage

water discharged after being used in a household or in a process, or produced by a process, other waters in a combined system and water that has infiltrated a sewerage system

[ISO 6707-1:2014]

4.9.20       water distribution system

water supply system, including pipes, valves, and pumps

4.9.21       wet infrastructure

infrastructure improvements which include water distribution system, storm drainage systems, and wastewater systems


5.    Conventions

5.1    Abbreviations

In this document the following abbreviations and acronyms are used or introduced:

bSI             buildingSMART International

GML                     Geography Markup Language

IFC            Industry Foundation Class

ISO            International Organization for Standardization

LADM      Land Administration Domain Model

OGC         Open Geospatial Consortium

UML         Unified Modeling Language


5.2    UML Package and Class Diagrams

The Conceptual Model contained within this document uses UML2 in accordance with well-established conventions adopted by the OGC and ISO TC211.  Boxes shown within the UML Package and Class Diagrams are color coded as follows:

Blue represents Classes defined in this standard (internal) that are part of the Requirements Class being specified:


Beige represents Packages and Classes defined in this standard (internal) that are part of another Requirements Class other than the one being specified:


Pink represents Packages and Classes defined in other (OGC or ISO) standards (external):


Green represents possible Packages and Classes in future extensions to this standard:


Other colors may be specified as appropriate.


5.3    Requirements

When referred to in a Requirement or Requirements Class, the boxes contained in UML figures may all be called “Classes” even if they are data types, enumerations, code lists, unions etc.  Because this is a Conceptual Model, they all should be interpreted to be concepts (see clause 6).

When a Requirement states that “The Requirements Class Classes shown in blue in Figure [nn] shall be provided for by the encoding in a manner consistent with the encoding.”, unless specified otherwise, this means that the encoding must support:

  1. all classes shown as blue boxes (this Requirements Class) in the figure
  2. all attributes, attribute cardinalities, and attribute data types of these classes (usually shown in subsequent figures)
  3. all associations, navigation, roles, and role cardinalities connecting to the blue classes
  4. all classes shown as beige boxes (another Requirements Class) in the figure connected to the blue box classes by association or used as attribute data types
  5. all classes shown as pink boxes (another Standard) in the figure connected to the blue box classes by association or used as attribute data types


The URI base for this standard is All URIs of Requirements Classes, Requirements, and Conformance Classes are relative to this base.


6.    Conceptual Modeling (informative)

ISO 19101 [9] defines universe of discourse to be a view of the real or hypothetical world that includes everything of interest.  That standard then defines conceptual model to be a model that defines concepts of a universe of discourse.

The scope of this LandInfra Standard establishes the limits of the universe of discourse for this Standard.  The next task is to discover and standardize the concepts within this scope.  LandInfra will potentially support numerous diverse application software packages covering multiple disciplines and facility life cycle phases.  Each conceivably can have its own universe of discourse and a corresponding set of concepts.

The goal of this LandInfra Standard is to establish and document a common set of concepts that spans the applications supported.  This does not attempt to redefine application concepts, but merely present a common set of concepts from and to which their concepts can be understood and mapped.

GML and IFC encodings are planned and other encodings are anticipated.  Each encoding addresses a specific information community and set of application software packages.  However, with the increasing desire to share information between communities and applications having a common conceptual model across all of these encodings is highly advantageous.

An added benefit of the development of a conceptual model results from the rigor involved in achieving consensus.  After numerous iterations, the end result is consistent, cohesive, and complete.  Updating a conceptual model is far easier than rewriting software code.  Further, the iterations help to flesh out details as well as to unearth differences in individual conceptualizations.

Perhaps the greatest benefit of the standards activity is the ability to communicate the resultant model. This is in part due to using a standardized conceptual modelling language like UML and the agreed OGC and ISO TC211 conventions for using UML.   The eventual outcome of being able to provide formal documentation for what is meant by each concept is invaluable in understanding the subsequent encodings and applications.

This will be the first OGC conceptual model standard, without accompanying encodings.  Yet the model is presented in a manner consistent with the formalisms adopted for writing OGC standards.  This standard follows the OGC Specification Model standard for modular specifications [10] and is consistent with the OGC Naming Authority conventions and recommendations.  The targets of this Standard are the encoding standards which will follow and not the application software that will implement these encodings.  Requirements for the encodings are explicit and grouped into Requirements Classes.  Accompanying Conformance Classes are included to determine if an encoding conforms to the conceptual model.

UML has been used as the conceptual modeling language in this LandInfra Standard.  Class Diagrams have been created and inserted as Figures.  The boxes in these diagrams (officially “Classifiers” in UML) typically represent classes, data types, enumerations, code lists, unions, etc. and this terminology is used throughout the Standard.  However, since this is a Conceptual Model, these should all be interpreted to be “concepts”.  For each Requirements Class, an introductory diagram is included which contains all of the concepts relevant to that Requirements Class.  However, the boxes are simplified by suppressing attributes.  These attributes are provided in a series of context diagrams which follow, each focusing on a particular set of concepts in the Requirements Class.

Though redundant with the UML diagrams, all of the class attributes are repeated in the document text, including attribute definitions not visible in the diagrams.  If these differ, the UML takes precedence.  Because association roles behave similar to attributes, they appear at the end of the textual attribute listing as if they were attributes.  The cardinality of the association is depicted as the attribute cardinality and the associated class as the data type.

7.    UML Conceptual Model (normative)

7.1    Structural Overview of Requirements Classes

The Requirements Classes for this standard are structured as UML Packages in Figure 1. Below is a brief summary of the function of each of these Requirements Classes.


LandInfra is the core Requirements Class and is the only mandatory Requirements Class.  This class contains information about the Land and Infrastructure dataset that can contain information about facilities, land features, land division, documents, survey marks, surveys, sets, and feature associations.  LandInfra also contains the definition of types common across other Requirements Classes, such as the Status CodeList.


Facilities include collections of buildings and civil engineering works and their associated siteworks.  The Facilities Requirements Class includes the breakdown of facilities into discipline specific facility parts and introduces the notion of elements which make up these parts.  The Facilities Requirements Class only provides general support for facilities themselves, allowing subsequent Requirements Classes to focus on specific types of the parts that make up facilities, such as road and railway.  This Requirements Class is optional in order to allow for the condition where all of the LandInfra dataset information is not facility related, such as one containing only survey or land division information.


A project is an activity related to the improvement of a facility, including design and/or construction.  This class may be for the creation, modification, or elimination of the entire facility or a part of the facility.  The Project Requirements Class includes information about projects and their decomposition into project parts.  In order to allow for the condition where none of the LandInfra dataset information is project related, this Requirements Class is optional.


An alignment is a positioning element which provides a Linear Referencing System for locating physical elements.  The Alignment Requirements Class specifies how an alignment is defined and used.


The Road Requirements Class supports those use cases in which a designer wishes to exchange the output of the design with someone who is likely to use it for purposes other than completing the road design.  Consequently, the Road Requirements Class includes several alternative ways for representing a design such as with 3D RoadElements, 3D StringLines (aka profile views, longitudinal breaklines, long sections), and 3D surfaces and layers, as well as collections of these. 


The RoadCrossSection Requirements Class extends the Road Requirements Class by adding the 2D CrossSection alternative way of representing a design, as well as collections of these. 

RoadDesign (future work)

The RoadDesign Requirements Class will support designer to designer information interchange, such as would exist when a designer other than the original designer takes over the design process to complete the design.  It is anticipated that the (future proposed) RoadDesign Requirements Class will cover design information in support of those use cases which involve the exchange of design information between designers.  It therefore would include DesignTemplates and SuperelevationEvents.


The Railway Requirements Class supports those use cases where a designer wishes to exchange the output of the railway design with someone who is likely to use if for purposes other than further design. Consequently, the Railway Requirements Class covers design output such as 3D railway elements and track geometry including superelevation (cant).


The Survey Requirements Class is the main survey class and provides a framework for information about observations, processes and their results collected during survey work. The content of this package is similar to the OGC Sensor Model Language (SensorML). The main reason not to use the SensorML standard for this topic is to allow the observation and processes structured in a compact way similar to the LandXML format. Due to the high number of classes the Survey Package was split into different parts, Equipment, Observations and SurveyResults.


In the Equipment Requirements class all information about the processes and the sensors is available that had been used for the determination of an observation.


Observations Requirements class is the package containing all information about the raw observations and the measurements observed during survey work. The raw observations are needed to enable later reprocessing or reporting of resulting properties of the observed feature of interest.

Survey Results

The SurveyResults Requirements Class contains the observed property of a feature of interest.  Using sampling features from the Observation & Measurements (O&M) standard, the dependencies between the observation acts and the results are realized.


Features of the land, such as naturally occurring water features and vegetation are specified in the LandFeature Requirements Class as land features.  Also included are models of the land surface and subsurface layers.  Improvements to the land such as the construction of an embankment or the planting of landscape material are considered to be part of Site Facilities in the Facility Requirements Class.


Land can be divided up into land divisions.  These can either be public (political, judicial, or executive) or private in nature.  The former are administrative divisions and the latter are interests in land.  Both of these are specified in the LandDivision Requirements Class, though condominium interests in land are specified in a separate, Condominium Requirements Class.


A condominium denotes concurrent ownership of real property that has been divided into private and common portions.  The Condominium Requirements Class includes information about condominium units, buildings and schemes.



Requirements Classes as UML Packages with their dependencies
Figure: : Requirements Classes as UML Packages with their dependencies

Figure 1 also shows (external) OGC and ISO standards as Packages on which Requirements Classes in this Standard depend.  Below is a brief summary of the function of each of these Standards.


Provides most of the geometry types (e.g., Point, LineString, Polygon) used for spatial representations in this Standard.

OGC-ASTopic2 - SpatialReferencingByCoordinates

Defines Coordinate Reference Systems.


Defines the linear referencing concepts (e.g., linear element, distance along, Linear Referencing Methods) used for linearly referenced locations in this Standard.


Defines a conceptual schema for observations, and for features involved in sampling when making observations.


Provides the core data types (e.g., CharacterString, Date, Boolean) used in this Standard.


Defines the General Feature Model upon which this Standard is based.


Identifies the metadata to describe digital geographic data.

ISO-19130-Imagery sensor models for geopositioning

Identifies the information required to determine the relationship between the position of a remotely sensed pixel in image coordinates and its geoposition.




7.2    Core Requirements Class: LandInfra

Core Requirements Class /req/land-infra

Target type

Encoding of the conceptual model































LandInfra Core Requirements Class
Figure: : LandInfra Core Requirements Class

LandInfra is the core requirements class, as shown in Figure 2.  The root class, LandInfra, specifies the Land and Infrastructure dataset. 



Requirement /req/land-infra/dataset

A Land and Infrastructure encoding shall specify a LandInfra dataset in whatever format that is appropriate to that encoding (e.g., an XML document for a GML encoding).


The dataset may contain any number of occurrences of each of the following: facility, land feature, land division, survey, document, survey mark, set, and feature association.  The first four are subject areas addressed by explicit requirements classes. 

Requirement /req/land-infra/subjects

A Land and Infrastructure encoding shall specify which of the LandInfra subjects it supports: Facility, LandFeature, LandDivision, and Survey.


The LandInfra Requirements Class contains classes (Figure 3) and data types (Figure 4) common across multiple subjects.




7.2.1    LandInfra Requirements Class Classes

LandInfra Requirements Class Classes
Figure: : LandInfra Requirements Class Classes

Requirement /req/land-infra/classes

The LandInfra Requirements Class Classes shown in blue in Figure 2 shall be provided by the encoding in a manner consistent with the encoding.    LandInfra Dataset Class

The LandInfraDataset Class contains header information (metadata) about the LandInfra dataset:

datasetID:  user defined unique ID used to identify a LandInfra dataset

name:  optional user defined name of the dataset

description:  optional description of the dataset

dateTime:  date and time that the dataset was created and therefore the point-in-time for which the data is valid

datasetVersion:  version number of the dataset

application:  software application (including version) used to generate the dataset

author:  person or organization which created this dataset

infraVersion:  version number of the Land and Infrastructure encoding

language:  language used in the dataset for CharacterString data types, default = English

defaultCRS:  default coordinate reference system which is used for all spatial representations within the dataset except where overridden by the or any individual SpatialRepresentation.geometry value

facility:  any number of Facilities

landFeature:  any number of LandFeatures

landDivision:  any number of LandDivisions

document:  any number of Documents

mark:  any number of SurveyMarks

survey:  any number of Surveys

set:  any number of Sets

featureAssociation:  any number of associations between Features


Requirement /req/land-infra/crs

An encoding shall support coordinate reference systems in accordance with OGC Abstract Specification Topic 2, Spatial Referencing by Coordinates.    Feature Class

The LandInfra Feature class is a specialization of the ISO 19109 AnyFeature Class.  (See 7.2.7, ISO 19109 Application Schema below.)  Additional Feature Types appropriate to the supported LandInfra subject areas will be further specializations of the LandInfra Feature Class.  They will therefore inherit the following LandInfra Feature Class attributes:

featureID:  user defined ID used to identify the feature instance, unique within the LandInfra dataset or globally unique with the inclusion of an ID.scope value

name:  optional user defined name of the feature

description:  optional description of the feature

spatialRepresentation:  the optional spatial representation (geometry and location) of the feature specified here with a value type of SpatialRepresentation.  Specific subtypes of Feature may make spatialRepresentation mandatory and may specify a more restrictive set of allowable subtype(s) of geometry (see 7.2.5).

linearlyReferencedLocation:  the optional linearly referenced locations of the feature expressed as specified as a LinearlyReferencedLocation in OGC Abstract Specification Topic 19, Linear Referencing (see 7.2.6)

property:  any number of Properties

propertySet:  any number of PropertySets

FeatureID shall be unique across all Feature instances in the LandInfra dataset.  Feature subtypes typically also have an ID, unique across that subtype.  In either case, the ID can be made to be globally unique with the inclusion of an ID.scope value.

Requirement /req/land-infra/featureID

An encoding shall specify if it supports ID at the feature level, ID at the Feature sub-type level, or both.    Document

A LandInfra dataset can contain information about any number of Documents.  It has the following attributes:

documentID:  user defined unique ID used to identify the document, unique within the dataset or globally unique with the inclusion of an ID.scope value

documentType:  the type of document, e.g., Condominium scheme

documentContent: optional filename of a file containing the actual document    Survey Mark

A SurveyMark is a physical object which by its form defines a point on the surface of the Earth and which is stable during surveying operations.  

identification:  optional, user-defined identification

spatialRepresentation:  one or more SpatialRepresentations having geometry of type Point    Property

An individual end user defined property (attribute) added to a Class.

name:  name of the Property

description:  optional description of the Property

valueType:  the data type of the value of this Property

value:  the actual Property value(s)

units: optional unit of measure of this Property

Not to be confused with “Property” in terms of real estate or immobile property which is addressed in 7.10.1, LandDivision.    Set

Set is a general purpose collection class used to group instances of a particular class and to provide information about that grouping.  Subtypes of Set are defined based on the types of things they can contain.  Set contains the following attributes:

name:  name of the Set, unique within the Set subtype

description:  optional description of the set and/or its contents

authority: optional authority for which the set is defined    PropertySet

PropertySet is a subtype of the Set general purpose collection class used to group instances of a particular class (in this case Property) and to provide information about that grouping.  PropertySet has the following attribute:

property:  one or more Properties in the set


By having both Feature Property and PropertySet allows for the specification of both individual properties and/or groups of properties for the Feature.    Professional

In this LandInfra Standard, Professional is a person who has acquired advanced knowledge and is a member of an association with the obligation to adhere to ethical standards and to act with probity in relation to its clients and to the public. The association and the state establishes entry criteria, issues licenses, and often arranges for disciplinary tribunals [11].

Professional has the following attributes:

name:  the name of the professional person

type:  the name of the professional discipline

company:  the optional name of the company through which the professional offers service

registration:  an optional key or identification regarding the license(s) or similar authorization by the competent authority.  Reference to the professional’s case identification is specified in section 7.10.4, Statement, caseID.

licensingCountry:  optional 3 character ISO country code for the country of the authority who issued the license    FeatureAssociation

The general purpose FeatureAssociation allows an implementation to dynamically create binary associations between any two Features in support of the Generalized Feature Model in ISO 19107.  If a specific association has already been identified as a requirement in LandInfra, it is accommodated by a Feature to Feature association within a specific Requirements Classes.  The general FeatureAssociation class has the following attributes:

name:  name of the FeatureAssociation

description:  optional description of the FeatureAssociation

fromFeature:  the Feature considered to be the “from” Feature

fromRole:  the role that the fromFeature plays in the FeatureAssociation

toFeature:  the Feature considered to be the “to” Feature

toRole:  the role that the toFeature plays in the FeatureAssociation



7.2.2    LandInfra Requirements Class Types