The tools in Locator and Spatial do not include translate (move), rotate and scale functions. I have developed the first two of these and have written about them in the referenced articles. In this article I show how to use the last of these, a Scale function, which I have just developed. Here is the function’sRead More
I thought I would try and create a table comparing all the native spatial types of the main database products around today. Because this is a “work in progress”, I will be contantly updating it. Where I have something wrong or have missed a product, please email me and I will correct the table. ReginaRead More
I came across the Maps Of War website today – isn’t it amazing that you can Google all you like but completely missing interesting websites. On the site is a cool shock wave flash (SWF) “movie” showing the various empires that have conquered part or all of the middle east since recorded history. It isRead More
I have a MOVE/ST_TRANSLATE function in my GEOM PL/SQL package that moves all the points in an SDO_GEOMETRY object by a shift vector defined as a delta x and delta y. But when I considered the idea of moving an SDO_GEOMETRY linestring object a set distance parallel to itself then the MOVE function becomes pointless asRead More
Yesterday, Tuesday 20th January 2009, I gave a flawed, imperfect, rather long talk called Free And Open GeoData – From Shadows to Reality at the March South Together, linux.conf.au 2009 Conference at the University of Tasmania. If one wants to get a message across, and perhaps be entertaining, one has to sprinkle one’s talk withRead More
One very useful function that is missing in Oracle Spatial/Locator is the ability to rotate an sdo_geometry object. A few years ago I wrote a function in my free PL/SQL packages but recent work with PostGIS occasioned my going back to that function and updating it. The function, and its overloads, are: Let’s explore rotation.Read More
This is not a spatial article but an article on how to limit the list of objects returned to an ODBC client (eg Access) on initial connection. One of the problems users face when connecting ODBC clients to an Oracle database is that the list of objects (tables, views etc) returned includes all the schemasRead More
Note: This article was edited on 1st March 2012 to cope with situation where all inner rings are filtered away by the change to using SDO_AGGR_SET_UNION which is not subject to the same licensing as SDO_AGGR_UNION. The changes are reflected only in the Filter_Rings PL/SQL function at the end of this article. In addition, aRead More
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
This is my first blog article on PostGIS. On the PostGIS discussion list, a question was asked: > I have a polygon table that has many small areas and holes. Now, I would > like to remove small areas and holes that are 2800 m^2. > > Any help or advice would be really appreciated.Read More