Reflecting a geometry around a line
The STReflect function allows for any input geometry (point, line or polygon) to be reflected around a supplied 2-point line of reflection (LineString).
Articles
Implementing Point-based Costs in pgRouting
Implementing Point-based Costs in pgRouting pgRouting is a great tool but it does have certain limitations. One limitation is that one cannot have costs at specific nodes. All costs have to be edge based. Discussion on Node/Edge Costs in pgModeler For example, suppose a network has a stop valve between two pipes. Normally the stopRead More
Using SQL Server XML and Spatial to import VicMap seed/Incremental Update Format (IUF) data (Part 3)
This is the 3rd and last blog post about processing VicMap IUF XML data. (The 6 month delay is because I lost a draft of this article, and have been doing other things.) While much in this and the previous articles are about an Australian XML data format, the principles outlined remain the same. ThisRead More
SQL Server Spatial Services 2008+
The SpatialDB Advisor, since 2007, has provided training and support services for the Spatial enhancements of Microsoft SQL Server 2008+. These services are designed to help customers fast-track their take-up of the technology within their business environment. Microsoft’s adding of spatial capabilities to SQL Server 2008 continued the trend of major vendors providing native spatialRead More
Getting the number of coordinate dimensions of a geometry/geography object in SQL Server 2008
The OGC standard has an STDimension() method defined on geometry/geography objects and this is implemented in SQL Server 2009. This function returns the inherent (or topological) dimensionality of an object: for a point this is 0; for a linestring this is 1; and for a polygon this is 2. name dim Point 0 LineString 1Read More
STDumpPoints: A Function that Dumps the Vertices/Points in a geometry
I often find I need to manipulate the points of a geometry/geography object directly in SQL. Oracle has the neat TABLE function mdsys.sdo_util.GetVertices( sdo_geometry ) for this. Since SQL Server 2008 does not have such a function I found I had to write it myself. I prefer to program in TSQL using the OGC geometry/geographyRead More
toGeography and toGeography Conversion Functions for SQL Server 2008 Spatial
I have been doing some SQL Server 2008 programming lately and have come across the fact that TSQL does not allowing a programmer to create overloaded functions. This is an issue, when programming SQL Server 2008 Spatial, because of use of its implementation of two different data types for geodetic and projected data: geography andRead More
Spatial Sorting of Data via Morton Key
I have often advocated the use of a spatial sort when loading static spatial data into Oracle (See 1. Spatially sort read-only data. in my article on performance tips). The idea here is to try and place spatial data that is close together in space (called spatial autocorrelation), close together on disk. Then, when theRead More
Write text file with spatial data from SQL Server 2008
Trivial I know, but here is a method for writing the result of a query (select) to a text file where the query contains either geometry or geography data. To do this we will use the xp_cmdshell stored procedure to call the external sqlcmd tool. To do this, first, we must allow SQL Server toRead More
TSQL String Tokenizer Function for SQL Server
Update: Tokenizer has been updated for Denali analytic features and to expose the separators in the output. We often have need of string tokenizers in applications. I had need of one in some TSQL development I am currently doing for a customer. I had previously written one for Oracle so I decided to re-write it forRead More