In some situations Quadrilateral polygon geometries in SQL Server Spatial can affect processing results. The best example of this is the identification of CircularStrings in polygon geometries. If quadrilateral objects are not identified, they end up being incorrectly converted. This function helps identify such polygon objects.
The STLineToCurve function analyses a LineString looking for CircularString elements among its vertices (often LineStrings are created from curve elements by “stroking” especially where the processing software does not support CircularStrings). Any constructed CircularStrings are combined with other LineStrings to create CompoundCurves or CurvePolygons.
This article shows how to use PostgreSQL’s XMLTABLE XML operator to process GML data and create PostGIS geometries.
The STReflect function allows for any input geometry (point, line or polygon) to be reflected around a supplied 2-point line of reflection (LineString).
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
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
BIT (Before Internet Time) it was probably true that we had a very small circle of friends or acquaintances. These people, whether family, friends and colleagues, were people we had actually (physically) met. As part of meeting people, one comes to some sort of estimation as to quality of their friendship, their character and reliability.Read More
“Imitation is the Greatest Form of Flattery” Before I talk about SSMS, pgAdmin and DBeaver spatial visualisation solutions, some history about the first spatial tool that extended a (non-GIS) database management and development tool: GeoRaptor. GeoRaptor History Many years ago a visionary programmer added spatial capabilities to SQL Developer 0.9, calling his extension GeoRaptor (theRead More
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:
Solutions are built by layering technology, from the simple to the complex. Nothing more illustrates this than considering network analysis. Firstly, most Geographic Information Systems (insert your favorite here), and database vendors like Oracle and PostgreSQL/PostGIS provide a basic routing engine. And what they offer is generally basic: a network or graph model, functions forRead More