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
Introduction NOTE: This article is a copy of the original first written in 2010 from my old website. Space curves are imaginary lines that systematically cover all tiles in an indexed space. The most well known in GIS is the Morton key. The utility of such a number can be seen though its implementing aRead More
I have often advocated the use of a spatial sort when loading static spatial data into Oracle (See 1. Spatially sort read-only data. in my article on performance tips). The idea here is to try and place spatial data that is close together in space (called spatial autocorrelation), close together on disk. Then, when theRead More
The most critical property of an image catalog that needs to be defined on its creation (using the Catalog Registry Tool) is the size of an individual tile. The scientific basis for what I am about to say was an published paper by Dr Peter R. Lamb (CSIRO Division of Information Technology) entitled: Tiling VeryRead More
I thought I would start a dedicated section on my site for the Manifold GIS based Image Catalog Tool. Introduction Image catalogs are used in ESRI technology, Manifold GIS and software such as the UMN MapServer. My image catalog tool, while not perfect, does (once you have mastered the tool and built some management practicesRead More
Today I uploaded to this site 2 videos show how to use my Manifold ImageCatalogTool to create, manage and populate disk-based image catalog. Image catalogs are used in ESRI technology, Manifold GIS and software such as the UMN MapServer. My image catalog tool, while not perfect, does (once you have mastered the tool and builtRead More
My latest article was published on Directions Magazine yesterday. The article is Scalable Server-side In-database Geoprocessing (thanks to Nora Parker and Adena Schutzberg). While Tim Osborn gave the presentation (and generated the statistics and charts) all the design and implementation of the performance improvements was done by myself. All ideas have their genesis. It was somethingRead More
Over many years I have created many image catalogs for distribution inside GIS systems and web mapping applications. The main science behind my implementations has been Peter Lamb’s work at the CSIRO (see my links page for the URL to Peter’s web page). What is missing from all GIS around today is abstracted management ofRead More