Previously I created the following Java stored procedures to enable the import/export of ZM aware WKT. ST_GeomFromText ST_GeomFromEWKT ST_AsText ST_AsEWKT These functions are necessary if one wishes to exchange geometry data with users of other databases that support WKT functions for 2D, 3D or 4D (ZM). For example, PostGIS supports the EWKT format and providesRead More
We all make mistakes. I made a good one this month. I had to modify (DDL) a very, very large table to change the size of existing columns. I didn’t think that this would cause me any problems, and so I didn’t drop any indexes. Was I ever wrong! Checking why it was taking soRead More
Oracle allows single part and multipart geometry objects to existing in a single SDO_GEOMETRY column. For example, a polygon and a multipolygon. This is because the SDO_GEOMETRY object type is singly inherited. (This also means that a single column can also hold geometries from different geometry types eg points, lines and polygons: common in CADRead More
Here is a function that takes a any polygon whose elements are defined by an optimized rectangle and converts all elements to 5 vertex polygons. Polygon may be multi; may have non-optimized rectangle components. Does NOT process geometries with compound elements. Now let’s test the function: Results are as follows: DESCRIPTION VALIDORIGINALGEOM VGEOM POLY SingleRead More
The populate CENTROID package has been modified. It now allows the caller of the CENTROID_A function to invoke Y ordinate seeding. This is what it looks like. I hope this enhancement is of use to someone.
UPDATE: This function is now a part of the Oracle Object implementation. The Travelling Salesman is a well known problem in graph theory: The Travelling Salesman Problem describes a salesman who must travel between N cities. The order in which he does so is something he does not care about, as long as he visitsRead More
UPDATE The original functions have been modified and deployed via my Oracle Object code. They original code is no longer available. My COordinate GeOmetry (COGO) package has been around for a long time. What I had not done was use the power of this package to construct polygons (2003) or linestrings (2002) from a startingRead More
This article describes a function that can be used to returns a compass point From a whole circle bearing (0-360)
The CENTROID package that I make available for free exposes a function for generating centroids of polygon (or area) objects. Here is the function: If you call the function with its defaults, the p_method parameter will be 1. For this value, the code determines the X ordinate extent of the polygon’s MBR, and selects theRead More
It is amazing what one finds inside an Oracle database! When writing pl/sql code I often have need to print out formatted strings. I have often wanted Oracle to have an equivalent to the C sprintf or Java format functions. Well, just the other day I discovered: See Format Message You will note from theRead More