The background to this blog comes from two separate sources: the first is my testing of SQL Server 2008 “Katmai”, and secondly, a blog article that Charlie Savage wrote a while back on The Sad State of GIS Web Standards. Web Mapping Standards As an ex-GIS Manager who monitored GIS standards for possible deployment withinRead More
Introduction The OGC operators for geometry processing only support two polygon inputs. Additionally the Microsoft aggregate operators only include geometry union processing geometry::UnionAggregate and not overlay processing etc. UnionAggregate returns for all input polygons as the single Union (see above) does. Concept: Resolving all overlapping areas, without dissolving boundaries, is called “planar enforcing”. Planar enforcementRead More
Comment: This article was written about 10 years ago. Most of what is written is still relevant though the comments about disk usage and access do not apply if SSD is being used. Introduction There are lots of things one can do to improve performance in mapping environments because of a lot of the visualisationRead More
Introduction Warning: This article is long mainly because it includes the source code of the Hilbert, Morton and Peano key/curves. I would assert that space filling curves have always been overlooked in their use within GIS. Their existence was/is rarely taught at Universities, though at least in my day. Perhaps today it is different (butRead More
This blog presents functions for Bing Maps Tile System for TSQL. This support includes converting Latitude/Longitude pairs to Bing Maps QuadKeys. The source for the functions is over at the Mircosoft site – an article by James Schwartz. They are donated to the public domain. Some tests include: I hope this is of use toRead More
GIS Desktop Software is the bedrock of how most people experience Geographic Information Systems. A limited selection of such products are: ArcGIS Manifold MapInfo qGIS FME (Feature Manipulation Engine) – not strictly a GIS but it can do most of the above. I have experience with all of the above. If anyone wants some help,Read More
The lack of an array datatype in TSQL can be overcome for geometry processing by use of a GeometryCollection as a data type and a set of methods to manipulate it.
This article demonstrates the power of database-based spatial processing. The business requirement is to determine, dynamically, the side of a land parcel that faces the street (could be single 2 point straight line to something more complex), and then determine the clockface direction from either ends of the frontage or the middle, to a object in the roads reserve (eg telecommunications pit).
This article shows how to create a GeoJSON Document from Selection of SDO_Geometry objects.