Core Concepts

This section provides explanations of terms relevant to City apps.

Building Address Point (BAP)
A mapping between points (latitude, longitude) and some address attributes. When searching for addresses (through the search box in the top bar), the search is run on all these attributes. This means that you can search for a street name, a postal code, or a city.

Reverse geocoding associates an address to geographic coordinates, which makes the identification of locations easier. Reverse geocoding uses the following attributes which are the only attributes that can be displayed in the Information panel:

  • HOUSE_BLK_
  • ROAD_NAME
  • BUILDING_N
  • POSTAL_COD.

You can also search for BAPs per referential. To do so, the search is run on documents with a "{ReferentialTitle}_BAP" title, where {ReferentialTitle} is a unique name and stands for the created and selected referential. If a specific document is found, a notification is displayed. Otherwise, the BAP document is used (provided that such a document exists).

The supported formats for BAP files are CSV, FGDB, GeoJSON, GML, KML, and SHP, providing that they contain point gemetries.

The document title can be either:

  • "BAP" to make it valid for all the referentials found on the tenant.
  • "{referential}_BAP" to get it selected in priority for one specific referential of the tenant.

Coordinate Reference System (CRS)
A system allowing to locate geographical entities on the Earth's surface.

EPSG codes provides and easy way to define the projection system and its parameters, but also to check the consistence of associated data.

This means that each datasource must be correctly associated to a given CRS, either through its format (for instance, KML uses EPSG:4326), or through an associated .prj file.

Dataset
There are two types of datasets:

  • A list of viewable prepared items displayed in the Referential panel.
  • Items added to the current experience through the 3DSpace spatial indexing, or created by the user (such as bookmarks).

Exalead CloudView Indexing
The Globe service associated to the City widgets automatically indexes the geometries stored in the supported GIS documents as soon as they are correctly uploaded in 3DSpace. This indexing process can take up to several minutes after the upload.

Whenever a 3DSpace document (a datasource) is added to an experience, the NETVIBES index lets you retrieve and filter the geometries to be displayed (as well as their attributes).

Generic Building (also known as "Procedural Building")
A building modeled with a parametric system based on a series of rules (or "parameters") such as a building footprint or height.
GeoItem
Any City object that represents an item of the real or virtual world. For example a tree, a building, a terrain, administrative units, addresses, a network or a POI.
MapServer
A technology used to query servers providing geo-spatial data (either raster or vector) on a given area, in a given projection. MapServer lets you define layers for your spatial data, or even reproject the data from one CRS to another.
Performance Profile
A profile which lets you reduce the core quality level for optimizing performance. These profiles are defined by the City Referential manager to enable or disable some advanced 3D effects to optimize navigation.
Point of Interest (POI)
A marker used in navigation softwares and GPS devices to identify relevant locations on a map.
Quadtree
The quadtree decomposition consists in dividing every level into 4 to obtain the next level. This means that a tile at level N is represented by four tiles at level N+1. And as every tile gets the same size, every level is four times more defined than the previous one.

The number of tiles is defined in the performance profile and cannot be modified.

Referential
The basis of your 3D map and defines a unique identifier, a CRS, and a square geographic area delimited by two geographic coordinates: the left upper corner and the right lower corner of the square in this CRS (quadtree boundary).

The referential must be chosen and defined by a GIS expert to take into account all the datasets to be included or visualized in this area.

The referential can be neither modified, not removed. All the datasets associated to a given experience must be prepared in the same referential. Note that this does not apply to datasets in preview (datasources) which are compatible with all referentials.

Render Profile
A profile which lets you associate a rendering type (by tuning the material, the opacity, or the shading, for instance) to datasets loaded in your experience.
Simple Feature
A simple geometrical element (point, line, or polygon) which is not yet associated to any object in the City datamodel.

Prepared datasets consist of sets of datasource simple features with attributes and of data model elements, the two are put together in simple feature objects. A polygon simple feature associated with a height can then become a building feature.

When creating a simple feature, the STRID attribute is mandatory.

Specific Building
A georeferenced 3D model representing a building.

A specific building lets you precisely describe a model with a complex geometry, or for which a specific texturing (photorealistic, for instance) is needed.