spatial-queries.md

Spatial Queries

This section uses the iModel Console to execute queries against the Stadium sample iModel.

See Aspect Queries for instructions on opening an iModel in the iModel Console.

The Spatial Index

iModels have a special spatial index table to make spatial queries fast and builtin functions to make querying a bit easier. See learning docs and the tutorial

Queries

1. Find the bounding box of an element

   SELECT * FROM bis.SpatialIndex WHERE ECInstanceId = 0x200000063de

   Remember find an Id from your own iModel.

2. Find Elements within a bounding box

   SELECT e.ECInstanceId, c.codevalue FROM Generic.PhysicalObject e 
     JOIN bis.Category c ON c.ECInstanceId = e.Category.Id 
       WHERE e.ECInstanceId IN (
         SELECT ECInstanceId FROM bis.SpatialIndex 
           WHERE minx > 32575 AND maxx < 32690 AND miny > 31720 AND maxy < 31800 AND minz > 5.5 AND maxz < 36
       )

   NOTE: Joining on category is not necessary but it is informative.

3. Find only the glass within the bounding box

   SELECT e.ECInstanceId, c.codevalue, a.* FROM Generic.PhysicalObject e 
     JOIN bis.Category c ON c.ECInstanceId = e.Category.Id 
     JOIN DgnCustomItemTypes_SS_Steel_Structure.GlassElementAspect a ON a.Element.Id = e.ECInstanceId 
       WHERE e.ECInstanceId IN (
         SELECT ECInstanceId FROM bis.SpatialIndex 
           WHERE minx > 32575 AND maxx < 32690 AND miny > 31720 AND maxy < 31800 AND minz > 5.5 AND maxz < 36
       )

Next: Query Hierarchies