Application of Delaunay Triangulation and Inverse Distance Weighting (IDW) in Oracle for Soils Interpolation
This article shows how to apply Delaunay triangulation and inverse distance weighting (IDW) techniques for soils interpolation in Oracle.
GeoProcessing
Splitting a polygon using one or more linestrings
One of the geoprocessing functions that seems to be poorly implemented is the ability to clip a polygon using one or more linestrings such that the result is a number of polygons. Here is an example of someone asking for help on the Oracle Technology Network’s Spatial forum: I have a task where i haveRead More
isValid, isSimple, Dimension and CoordDim methods for SDO_Geometry
I have just added to my Java Spatial For Oracle (JS4O) project exposure of the JTS/Jaspa functions for: ST_IsValid ST_IsSimple ST_Dimension ST_CoordDim Here are the type signatures in the JTS PL/SQL package. Here is a test of these functions. I hope this is helpful to someone.
Topological vs Non-Topological Simplification/Generalization of Aggregated Area Geometies in Oracle
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
STExtractPolygon: Extract Polygons from result of STIntersection in SQL Server Spatial
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
STRound: Function to round ordinates of a SQL Server Spatial geometry object
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
STMove: Function to Move a geometry object in SQL Server Spatial
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
STRotate: Function to rotate a geometry object in SQL Server Spatial
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
Find all segments of a LineString within distance of a point
Recently I was asked: Is it possible to find all the line string with in certain distance from a point (lat, lon). It is a pretty simple question (if I interpret it correctly). Here is a solution for Oracle Spatial: Here is the input linestring and point and the result of the query:
Using Oracle’s SDO_NN Operator – Some examples
This little article was occasioned by someone emailing me and asking: Actually I do have a topic for you – clustering. Before we moved to Oracle Spatial, we had a request for a client to: “Show us all the stores that are close to each other”. I’m somewhat embarrassed to say that we did this byRead More