Open Geospatial Consortium |
Submission Date: 2021-05-11 |
Approval Date: 2021-06-18 |
Publication Date: 2021-07-02 |
External identifier of this OGC® document: http://www.opengis.net/doc/DP/NBLS |
Internal reference number of this OGC® document: 21-037 |
Category: OGC® Discussion Paper |
Editor: Josh Lieberman |
OGC Technical Paper on the Standards Landscape for Building Data |
Copyright notice |
Copyright © 2021 Open Geospatial Consortium |
To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ |
Warning |
This document is not an OGC Standard. This document is an OGC Discussion Paper and is therefore not an official position of the OGC membership. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an OGC Standard. Further, an OGC Technical Paper should not be referenced as required or mandatory technology in procurements.
Document type: OGC® Discussion Paper |
Document subtype: |
Document stage: Approved |
Document language: English |
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i. Abstract
Data about buildings and building structures play roles at scales from neighborhoods to nations in creating, protecting, regulating, and understanding the built environment. This report examines standards which may be useful in defining the structure and content of building data at a national scale, a "national building layer." Standard models, schemas, and encodings may be especially useful for supporting an extensible building dataset with an efficient core definition, but the ability to encompass more detailed or specialized data as needed in as seamless and compatible a manner as possible. Standards compiled and described in this document range from generic geographic data encodings to models and specifications for specific building perspectives such as land parcel improvements, facility ownership, footprint / roofline extractions, residency affordances, envelope characteristics, and so on. They provide potential source material for a modular and multi-platform building layer definition which can be applied to a reasonably wide set of use cases. This definition may in turn be a standardization candidate for adoption by other national geographic data collections.
ii. Keywords
The following are keywords to be used by search engines and document catalogues.
ogcdoc, OGC document, building, standard,
iii. Preface
Note
|
This document has originated in work undertaken by OGC staff on behalf of Natural Resources Canada, an OGC Strategic Member. 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):
Natural Resources Canada
v. Submitters
All questions regarding this submission should be directed to the editor or the submitters:
Name |
Affiliation |
Josh Lieberman |
OGC |
Joseé-Anne Langlois |
NRCan |
Ryan Ahola |
NRCan |
Jean-Samuel Proulx-Bourque |
NRCan |
1. Introduction
1.1. Motivation for this discussion paper
Buildings, dwellings, and other structures that provide us with indoor living, working, or storage space are the principal components of the built environment and also the top of the pyramid of infrastructure and services that make up that environment. Data about buildings has many uses, from mapping and property information to infrastructure protection and energy conservation. Many of these uses benefit from availability of standardized, comparable building data at national or even international scales. This report specifically details existing geospatial data standards and standardization efforts that pertain to the design of national building information layers in Canada. The report may also be relevant to building information standardization elsewhere in the world.
1.2. Building and building data concepts
Existing representations of buildings and building structures cover a very wide range of level of detail and depth of information, from simple points and rectangles for mapping purposes, through specific ownership and addressing information for cadastral purposes, to detailed 2D and 3D design and model information, even dynamic "digital twins" that represent a building’s current status and operation.
The following terms and concepts are useful in describing these different degrees and types of representation.
- Improvement
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Buildings and structures as value improvement attributes of land parcels.
- Address Point
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The geospatial point, usually a front door or street access point, corresponding to the street or mailing address assigned to that location.
- Footprint
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A polygon that delineates the extent of the building at the ground surface, usually derived by land survey or from design documents.
- Roofprint
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A polygon that delineates the extent of the building as seen from above, usually derived from aerial photography or LIDAR point elevations.
- Envelope
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A concept which may refer to a 3D-extruded polygon or more detailed surface representation of the building exterior and/or building properties aggregated over the building exterior skin, such as insulation value.
- Building model
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a digital representation of a complete physical building including one or more perspectives such as appearance, structural elements, open / navigable space configuration, utility systems, occupancy, etc. Perspectives may be static or include dynamic processes operating within and around a building.
1.3. Building data and data standards use cases
There are a wide variety of possible use cases for building data that each benefit from particular building representations, attributes, level of detail, related entities, and data quality. Data standards are agreements on how at some level of specificity to model and encode data. The more broadly they can address requirements for data exchange and compatibility across a greater variety of use cases, the more utility such standards can have.
One categorization of some 284 use cases collected from various Canadian government agencies ( 2019/20 NBL Consultation Results) might include:
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Buildings as cadastral improvements are a component of land parcel administration information covering ownership, tax and zoning status, regulatory compliance, property occupancy and usage, addressing, etc.;
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Buildings as systems exchange people and commodities with their surroundings and with larger utility and transportation systems;
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Buildings as critical infrastructure have history, characteristics, status, and obligations in terms of vulnerability, accessibility, resilience, condition, and utilization; and
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Buildings as assets have value, performance, and roles to play in business, social, and personal endeavors.
Use cases in these categories identify at least 174 building attributes of interest, but likely also involve differing building representations, levels of detail, and other design criteria for applicable building information elements. The applicability of data standards likely differs across these categories too, with more general standards having broader relevance, and more specific standards pertaining to smaller groups of use cases, but not necessarily bound to these particular categories.
1.4. Presentation of standards
Descriptions of standards in the rest of this report have been categorized according to their generality, what aspects of buildings they pertain to, and to some extent what form they take as data.
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Base standards specify general interoperable approaches for geospatial information or aspects of the built Environment.
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Parcel standards focus on compatible information about land parcels, administration, and improvements such as buildings.
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Building standards pertain to specific aspects of building natures, functions, and roles in the world.
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Standards synthesis looks at commonalities between these standards in terms of attributes and representations, then considers how they might complement each other for a modular, profiled, and/or linked building information model design.
2. Base Standards
The standards described in this chapter fall into 4 categories:
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Standards for geospatial feature data;
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Standards for elements of the build environment;
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Standards for sensing and observation data; and
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Standards for location / facility identification.
These standards generally do not provide specific attributes for features such as buildings, but instead specify how to create such attributes for specialized feature types.
2.1. Geospatial data standards
This standard is the most direct implementation of the fundamental ISO TC211 standards for 2D geospatial feature data, incorporating feature identity, feature schemas, and locators such as (simple) coordinate geometries in 2D and 3D space. This is the basis for most database storage of geospatial data layers and is itself an ISO standard (ISO 191251-1 Common Architecture and 19125-2 SQL).
GML is an implementation in XML Schema of the same ISO conceptual feature model standards as SF-SQL, but covers much more ground and is also a separate ISO standard(s) (ISO 19118 Encoding Rules and ISO 19136 XML Schema). GML is essentially a toolbox or application schema language for creating specific feature data schemas or specialized profiles. An important characteristic of GML, elaborated in the General Feature Model, is that feature geometry is considered an attribute of a feature, not the definition of it. A given feature such as a building can have a single identity but be represented in data by multiple alternate geometries, allowing the choice of an appropriate geometry according to scale and application of the data.
2.2. Built Environment standards
These general standards specify the design and encoding of information about features and objects in the built environment such as buildings and infrastructure.
CityGML through version 2 is an extensible GML application schema that models a great variety of elements of the built environment as children of CityObject. An important part of CityGML is the capability of defining extensions (Application Domain Extensions) that represent more specialized parts of the city infrastructure such as utility networks or more specialized attributes such as urban energy simulation data.
CityGML v.3 was approved by OGC in early 2021 and is based on its own conceptual model that contemplates implementations not solely based on GML (e.g., JSON). It introduces concepts and constructs such as Spaces in order to improve compatibility with other built-environment standards such as IFC and LandInfra, as well as dynamic elements that incorporate live sensed attributes into city objects.
https://www.ogc.org/standards/landinfra https://www.ogc.org/standards/infragml
LandInfra is a conceptual model implemented as a GML application schema (InfraGML) that focuses on land parcels, ownership details, surveys, and linear facility alignments such as railroad structures. It does also define facility entities that are not specific to buildings, but can be used to connect building structures with land units and ownership interests.
Industry Foundation Classes are a suite of standard specifications developed by buildingSMART International for interchange of datasets that make up BIM (Building Information Model) instances. IFC is essentially a common subset of vendor-specific building models such as Autodesk’s Revit, Bentley’s Microstation DGN, Graphisoft’s Archicad, or Trimble’s Tekla. Some vendors such as Dassault are now, however, supporting IFC natively on their platforms. IFC and CityGML have considerable overlap in coverage, but typically divergent representations (e.g., unique geographic features in CityGML vs. parametrized assemblies in IFC). A joint committee (IDBE)between OGC and buildingSMART International has made progress to increase the overlap or correspondence between CityGML, LandInfra, and IFC, but direct round-trip data conversion between any two of the standards will likely remain limited for the foreseeable future.
2.3. Observed / modeled feature properties standards
A number of standards cover the types of data typically involved in sensing the characteristics of geographic features such as buildings.
This standard, adopted by OGC as a Community Standard from ISPRS, is a compact format for the point cloud and signal data derived from LIDAR scan surveys. LIDAR is a common method for observing the 2.5D form of the Earth’s surface in very fine detail. LIDAR point clouds conflated with corresponding imagery can be used to visually and geometrically represent buildings directly. They are also commonly processed to extract building roofprints and even some roofing details such as gables and roof exposures.
The three standards above are core for the information needed to characterize the process of making sensor observations and applying the results as feature properties. The O&M conceptual model defines objects and relations pertaining to the observational process. SWE Common provides an encoding standard for observational data, while SOSA-SSN, a joint OGC-W3C product, is a modular OWL ontology built on and extending the O&M specification.
2.4. Identification standards
Management and interchange of global feature identifiers is a significant challenge in any large-scale heterogenous domain, particularly in order to make sure that in each identification scheme, each feature is referenced by one unique identifier. the GS1 standards organization provides the GLN (Global Location Number) specification that can be used to manage the identities of locations and facilities / buildings at potentially a global scale by means of ID keys.
3. Parcel and cadastral standards
These standards for parcel and cadastral information are included because buildings are often considered as improvements "belonging" to a land parcel, and so derive their location and identity from those parcels.
https://inspire.ec.europa.eu/documents/Data_Specifications/INSPIRE_DataSpecification_CP_v3.0.pdf
Within the EU INSPIRE data specification framework, cadastral parcels are treated as "…reference data, i.e., data that constitute the spatial frame for linking and/or pointing at other information that belong to specific thematic field such as environment, soil, land use, and many others." This is complementary to the specific national land ownership registries ("cadastres"), using a definition that "cadastral parcels should be, as much as possible, single areas of Earth surface (land and/or water) under homogenous real property rights and unique ownership, where real property rights and ownership are defined by national laws."
https://www.iaao.org/media/standards/Manual_Cadastral_Maps_2016.pdf
This is an international standard for digital parcel creation and management that focuses entirely on land parcels as components of a cadastre with uniform survey methods, digital representations, identifiers, and assessments of financial value. It actually cites a US FGDC (Federal Geographic Data Committee) standard for parcel core data elements, although not the latest (2008) version.
Part 1: Cadastral https://www.fgdc.gov/standards/projects/framework-data-standard/GI_FrameworkDataStandard_Part1_Cadastral.pdf
http://nationalcad.org/download/cadastral-data-content-standard-ver-1-4.pdf
These two standards provide a detailed data schema for cadastral parcels in terms of survey measurements, transactions, rights, and interests. It includes such possibilities as ownership under multiple geopolitical regimes, but only acknowledges the existence of buildings insofar as they are improvements that might need to be surveyed.
https://www.mass.gov/service-details/massgis-standard-for-digital-parcels-and-related-data-sets
The Massachusetts Office of GIS (MassGIS) has developed a standard for recording and exchange of digital parcel information, partially with FGDC grant support. This standard is also being used in some other states and cadastral jurisdictions. Among its specific characteristics:
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Assessor’s Record attributes including tax and other legal interest attributes;
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Assessor’s Record attributes including building data attributes;
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Guidance on parcel addresses and master address files;
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Linking between a deed-specific identifier (ParcelID) and a geographic identifier (LocID); and
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Linking / aggregation from specific physical parcels to tax parcels (TaxParID).
The MassGIS parcel standard is also notable in that it is at least minimally complemented by a building footprint / roofprint polygon data standard, e.g., the building footprint polygons are checked against the assessor recorded building area in the parcel data. There are few other building-specific attributes, however. The identifier is derived from the building centroid coordinates and the building footprint area is calculated directly from the building polygon.
The most notable characteristic of cadastral parcel data standards is how little they do consider the existence and characterization of buildings and other modifications to the state and value of a land parcel. This is surprising given the modern day value and volume of real estate transactions and interests that involve condominiums, building parts that involve land ownership only implicitly. The division between land and structure information is likely to be reflective of legal traditions in land ownership rather than the utility for a number of purposes of having these datasets linked together.
4. Building and Facility Standards
Data standards in this section all pertain to buildings but from differing perspectives of complexity, level of detail, and application purpose.
4.1. Structures standards
Structures standards specify minimal information about built structures of any type, primarily for the purpose of 2D mapping and as part of general spatial frameworks.
This link provides access to ArcGIS-specific data dictionaries that define the TNM schemas "Struct_Point" and "Struct_Line". There are links in the Struct_Point schema (Foot_ID and Complex_ID) to feature classes Structure_Footprint and Structure_Complex encode more detailed building geometries but include no more involved building attributes than area and perimeter length. Building information in this model is spread among 4 different tables due to the ArcGIS limitation of one geometry type per table / feature collection.
Besides providing various structure geometries for rendering in USGS topographic maps and assorted metadata about data loading and access rights, the Struct_ schemas focus on a handful of structure properties that are characteristic of other TNM feature data as well.
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FType - a 3 digit code defining the type of each structure. For example, 730 denotes an educational structure in the struct_point dataset.
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FCode - a 5 digit code repeating the FType code and adding 2 digits to further characterize each structure. 73005 denotes a high school building or group of buildings. For a struct_line feature, 75017 denotes an above-ground oil/gas pipeline.
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Permanent_Identifier - A 40-character globally unique ID (GUID) value that uniquely identifies the occurrence of each feature or event in The National Map.
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GNIS_ID - a unique ID assigned by the Geographic Names Information System that corresponds to the geographic feature name (i.e., placename) for the structure. This does provide a unique geometry-independent identifier for the building as a named feature, but not all buildings are recognized with placenames, and the GNIS_ID is disconnected from any local or cadastral identifier.
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Name - the official name corresponding to the GNIS_ID.
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Address
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City
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State
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IsLandmark - indicates whether the structure has been designated a landmark
https://www.usgs.gov/core-science-systems/ngp/tnm-corps/structure-definitions https://navigator.er.usgs.gov/help/WebHelp/structure_def_table.pdf
These tables provide detailed definitions of the various types of buildings or other structures defined by the Struct_ data dictionaries and denoted by FCodes, for example what is and is not considered a cemetery.
https://www.fgdc.gov/standards/projects/FGDC-standards-projects/RPADS/
This minimal data content standard is maintained by the General Services Administration, owner and operator of all U.S. Federal properties. It categorizes a real property asset as a building, land parcel, linear structure, or structure, provides a Federal identifier, name, and address, along with one or more simple geometries (point, line, polygon).
Spatial Data Standards for Facilities, Infrastructure, and Environment https://www.sdsfieonline.org (requires login account)
SDSFIE are a family of US Department of Defense data standards for definition and interchange of geospatial data specifically for installation, environment, and civil works missions. The SDSFIE-V| 4.0.2 standards for vector feature data as adapted for the U.S. Army include application schemas for these features:
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LandParcel
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Structure (and variants)
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Building
LandParcel, Structure, and Building (along with Site) features actually share a number of "real property" attributes, especially a Real Property Site Unique Identifier (rpsuid) which is able to link these collocated features together in a database. In fact there are few differences between the definitions of Structure and Building, except that for some reason Building includes a "Proposed Demolition Date" property and Site does not.
4.2. Buildings standards
The data standards in this category pertain specifically to buildings as distinct from non-building structures such as pipelines; they define generally 2D properties and geometries that are specific to buildings and building parts.
https://inspire.ec.europa.eu/documents/Data_Specifications/INSPIRE_DataSpecification_BU_v3.0rc3.pdf
The INSPIRE building data standard provides a conceptual model and various levels and/or types of detail through 4 profiles with implementations in CityGML, including BuildingsBase, BuildingsExtendedBase, Buildings2D, and Buildings3D. The profiles are defined by means of an inheritance hierarchy of structure types. Figure 13 shows features and building specific properties in the BuildingsBase schema. An AbstractBuilding inherits attributes from an AbstractConstruction class and adds building-specific attributes such as "BuildingNatureValue" and "currentUse". It is then realized in both Building and BuildingPart classes.
The base profile is extended with either 2-2.5D geometries or 3D geometries, as well as additional attributes to fill out the 4 profiles shown in Figure 14.
The BuildingsExtendedBase adds feature types for "OtherConstructions" for structures not considered buildings, "Installations" for small building additions, and "BuildingUnits" for independently accessible building parts. Mainly, though, it adds additional building attributes, as shown in Figure 15. Some of these relate to utility network hookups but only as boolean (yes/no) attributes.