A colleague wrote to me today asking: I’m looking for a way to improve a query to detect all line geometries which are shorter then 10 mm. … It takes days to check all our lines (full tabel scans on millions of rows); … Can’t I use the domain index to filter out the desiredRead More
My CENTROID PL/SQL package is a hot download from this site. It seems there is a need out there for variations on the generating of centroids. Recently I ported my centroid algorithms to SQL Server Spatial (Denali). In doing so a few improvements or changes were made. These include the ability to: Provide the centroidRead More
Oracle customers have asked me for help in the past dealing with compound objects or collections that result from thinning or geoprocessing (intersection etc) of geometry data. Normally this is the need to extract only polygons from the result of an intersection operation. This problem applies to SQL Server Spatial users are the following exampleRead More
The result of many geoprocessing operations in any spatial type can be geometries with ordinates (X, Y etc) that have far more decimal digits of precision than the initial geometry. I present here a simple function STRound that takes a geometry object and some specifications of the precision of any X, Y, Z or MRead More
Of the functions I have written for Oracle, those that allow me to extract (sub)elements of compound (objects consisting of linestrings and circular arcs) and multipart geometries have found use time and time again in such activities as: Filtering Rings of Polygons; Extracting homogeneous objects (eg point, line or polygon) from geometry collections. This articleRead More
Here is an “ease of use” function that allows you to count the number of rings of a polygon or multipolygon geometry object in SQL Server Spatial. Some tests. Resulting in: gtype numRings Point 0 MultiPoint 0 LineString 0 MultiLineString 0 Polygon Outer 1 Polygon 3 MultiPolygon 5 CurvePolygon 1 GeometryCollection 1 I hope thisRead More
A function that have found use in Oracle and PostGIS is one that allows a user to filter out the rings of a polygon or multipolygon based on area. Here is presented a function to do this in SQL Server Spatial. This function requires Denali (2012) as it uses unionAggregate. In addition, the function requiresRead More
If you have need for a TSQL based function for moving geometry objects in SQL Server Spatial (Denali is required), here is a function you might find useful. Now for some tests Point The result looks like this: Linestring The result looks like this: Move rectangle 10,10 The result looks like this: Curved polygon TheRead More
The top download from my website is for my package of centroid algorithms for Oracle sdo_geometry. There is nothing wrong with the STCentroid function implemented in SQL Server Spatial (for one thing it handles geography objects natively), but it seems that having a choice of centroid algorithms is a big thing for users of spatialRead More
If you have need for a TSQL based function for rotating geometry objects in SQL Server Spatial (Denali is required), here is a function you might find useful. Now for some tests Rotate rectangle about itself and the origin The result looks like this (the background light blue rectangle is the original): Point The resultRead More