Changes between Version 52 and Version 53 of WKTRasterTutorial01


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Timestamp:
Jun 11, 2010, 2:08:54 PM (12 years ago)
Author:
pracine
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  • WKTRasterTutorial01

    v52 v53  
    33''Pierre Racine, June 2010''
    44
    5 This tutorial will show you how to do a very classical raster/vector analysis with PostGIS WKT Raster. Basically the problem is to compute the mean elevation for buffers surrounding a series of point representing caribou observations. You can do this kind of analysis pretty easily in any GIS package but what is special here and is not easy to do in ANY GIS package is the size of the datasets used (900 MB or raster data), the simplicity of the queries and the speed at which we will get the results.
     5== Introduction ==
     6
     7This tutorial will show you how to do a very classical raster/vector analysis with PostGIS WKT Raster. You will get more info on PostGIS WKT Raster [wiki:WKTRaster in this page] but we can say that WKT Raster...
     8
     9 * is the raster format introduced by PostGIS
     10 * supports multiband, nodata value, georeference, overviews, overlapping tiles and non rectangular coverages
     11 * is not really limited in size (PostgreSQL has a limit of 32 TB)
     12 * is very well integrated with PostGIS geometries
     13 * comes with a very versatile Python raster loader (supporting batch loading through wildcards and as many input formats as GDAL does)
     14 * is not only a raster format but a SQL raster manipulation and analysis language
     15 * allows seamless and efficient intersections operations with vector tables
     16
     17
     18Basically the problem is to compute the mean elevation for buffers surrounding a series of point representing caribou observations. You can do this kind of analysis pretty easily in any GIS package but what is special here and is not easy to do in ANY GIS package is the size of the datasets used (900 MB or raster data), the simplicity of the queries and the speed at which we will get the results.
    619
    720We will describe the steps mainly on Windows, but Linux gurus will have no problem writing the equivalent commands in their favorite OS. We assume that PostgreSQL, PostGIS and PostGIS WKT Raster are well installed. Refer to the readme file of each software to install them properly. The version used are:
     
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    119132
    120 A quick overview of the properties of the raster table can be displayed with the following command:
     133A quick overview of the properties of the raster table (upper left corner coordinates, width and height, pixel sizes, skews - or rotations, SRID, number of band, pixel type, has nodata value, nodata value, is out db) can be displayed with the following command:
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    122135{{{