Spatial Solutions Architect and Database Expert
One activity that is very common when working with linear data is to be able to take a bunch of linestrings and collect them together into a minimal set of maximum length linestrings. The Java Topology Suite (JTS) has a LineMerger class that does this very nicely. I have integrated this into my Spatial CompanionRead More
I have exposed the JTS/Jaspa coordinate editing functionality via the ST_DeleteVertex function within my Spatial Companion For Oracle (SC4O). Here are some examples: I hope this is useful to someone.
Oracle Spatial does not read or write 3D Well-known text (WKT); nor does it read/write measures. Oracle’s SDO_Geometry implementation only supports the OGC Simple Features 1.1 specification which is 2D only. What I have done is expose the Jaspa/JTS implementation of methods more 3D+ aware to PL/SQL and therefore SQL via my Spatial Companion forRead More
Oracle has a function, sdo_util.simplify that can simplify (generalize) the vertices describing a geometric object (that is, reduce the number in a way that maintains basic shape). However, that function only operates on a single geometry at a time. Using it on polygonal data that completely covers an area (planar enforced) can and will causeRead More
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