Changes between Version 7 and Version 8 of WKTRasterGSoC


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Timestamp:
Mar 22, 2011, 12:14:50 PM (13 years ago)
Author:
pracine
Comment:

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  • WKTRasterGSoC

    v7 v8  
    2020 [http://www.quantdec.com/SYSEN597/GTKAV/section9/map_algebra.htm Map algebra] allows the creation of a new raster as a mathematical (or logical) function of one or two other rasters. e.g. raster3 = (raster1 + raster2) / 2. This is a very common raster operation in the GIS world.
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    22  A one raster version of ST_MapAlgebra already exist. We now need a two raster version. This version is much more complicated to implement as it must not only takes into account nodata values but also on-the-fly reprojection of non aligned rasters and multiple possibilities for the resulting extent when the two rasters do not have the same extent. It is also possible, but complicated, to optimize the algorythm in order to fill many areas as a chunck of data instead of pixel by pixel. The project includes reviewing the proposed algorythm and implementing it. You will familiarize yourself with PostGIS development (the most used open source geospatial database), geospatial imagery concepts, open source development tools and code in C and PL/pgSQL.
     22 A one raster version of ST_MapAlgebra already exist in PostGIS. To have a complete set of operators, we now need a two raster version. This version is much more complicated to implement as it must not only takes into account nodata values but also on-the-fly reprojection of non aligned rasters and multiple possibilities for the resulting extent when the two rasters do not have the same extent. It is also possible, but complicated, to optimize the algorythm in order to fill many areas as a chunck of data instead of pixel by pixel. The project includes reviewing the proposed algorythm and implementing it. You will familiarize yourself with PostGIS development (the most used open source geospatial database), geospatial imagery concepts, open source development tools and code in C and PL/pgSQL.
    2323
    2424Want more details? Write to the [http://postgis.refractions.net/mailman/listinfo/postgis-devel PostGIS developer list].