Changes between Version 12 and Version 13 of WKTRasterGSoC


Ignore:
Timestamp:
03/24/11 12:43:40 (14 years ago)
Author:
pracine
Comment:

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  • WKTRasterGSoC

    v12 v13  
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    5 1) '''Implement write support for the PostGIS raster GDAL driver.'''
     5'''1) Implement write support for the PostGIS raster GDAL driver.'''
    66
    77 Mentor: Jorge Arevalo (jorge.arevalo at deimos-space.com)
    … …  
    1313
    1414
    15 2) '''Two rasters version of the ST_MapAlgebra SQL function'''
     15'''2) Two rasters version of the ST_MapAlgebra SQL function'''
    1616
    1717 Mentor: Pierre Racine (pierre.racine at sbf.ulaval.ca)
    … …  
    2424 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.
    2525
     26'''3) Implement a set of geometry to raster functions'''
     27
     28    Mentor: Pierre Racine (pierre.racine at sbf.ulaval.ca)
     29
     30    With the ability to store geometries and rasters in postgis, there is now a gap to fill by implementing geometry to raster algorithms to allow transition from one type to the other.
     31
     32    1) '''ST_AsRaster''' takes a geometry and converts it to a raster.
     33
     34    2) '''ST_AsDensity''' takes a point or line geometry coverage and first assign a count of those features to every pixels of a raster coverage and then apply a smoothing filter (using the existing one raster version of neighbour ST_MapAlgebra). Density functions  allow summarizing or simplifying a point or line dataset.
     35
     36    3) '''ST_Interpolate''' takes a point (e.g. filtered lidar points) or line geometry (e.g. digitized topo lines) coverage to interpolate pixels values between geometries. There are numerous methods of interpolation and it would nice to have a generic method so we can use all of them, but we’re first targeting bilinear interpolation, which will fill most needs and lay the ground for other methods.
     37
    2638Want more details? Write to the [http://postgis.refractions.net/mailman/listinfo/postgis-devel PostGIS developer list].
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