Last edited 06 Oct 2022

City information modelling CIM


[edit] Introduction

City information modelling or CIM is in many ways a natural expansion of the now well-established building information modelling (BIM) that has become in the UK a prerequisite to many publicly-procured projects and an industry standard. It is in some respects a field that is still being established but connects well with the smartcity movement, city dashboards, and the gradual appointment of chief digital officers (CDO) across many major cities.

[edit] From product to building level

Building-level information used by building information models (BIM) may be standardised by the Industry Foundation Classes (IFC) data model, a neutral and open specification developed by the International Alliance for Interoperability (IAI). It uses an object oriented file format with a supporting data model to facilitate interoperability in the building industry. Industry Foundation Classes (IFC) is covered by ISO 16739-1:2018: Industry Foundation Classes (IFC) for data sharing in the construction and facility management industries — Part 1: Data schema. In practical and scaled terms its use extends from product level information to the level of the building or cluster of buildings on a site. further information can be found in ISO/TC 59/SC 13; organization and digitization of information about buildings and civil engineering works, including building information modeling (BIM).

[edit] From building to city level and beyond

City information modelling (CIM) extends beyond the building level up to the city level and potentially globally, as such it relies on geographic information systems (GIS) or geomatics. City information modeling (CIM) uses a spatial data exchange issued by the Open Geospatial Consortium (OGC) and is implemented as a Geography Markup Language (GML) application, a schema for the Geography Markup Language 3 (GML3) also known as City GML. City GML datasets are made up of a set of Extensible Markup Language (XML) files with associated images, textures or parts of the dataset giving the required level of detail.

The extension of these elements to creating city-level models currently relies on a 3-dimensional city database (3DCITYDB) which is open-access and free to use, store, represent and manage 3D city models. The database content can be directly exported to The 3D City Database. Content can be directly exported in KML (keyhole markup language), COLLADA (COLLAborative Design Activity), and glTF (graphics language transmission format) formats for the visualisation in a broad range of applications like Google Earth, ArcGIS, and the WebGL-based Cesium Virtual Globe.

[edit] Interoperability of systems

ISO/TC 59/SC 13/JWG 14 (joint working group between ISO/TC 59/SC 13 and ISO/TC 211) developed a technical report on GIS-BIM interoperability in 2021; ISO/TR 23262 GIS (geospatial) / BIM interoperability. The report includes the following three suggestions for further work:

1. Linking abstract concepts in BIM and GIS standards.
2. Geospatial and BIM dictionary.
3. Information exchange guidelines between BIM and GIS.

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