[postgis-devel] [WKT Raster] Regular blocking and null extent

[Pierre Racine]

>Certainly, if regular blocking coverage is empty, dimensions of extent
>rectangle are equal to Zero. 0
>
>Is that correct?

Probably yes. There is no similar example on the vector side as there is no (need for an) extent in the geometry_columns table.

>Shall we allow generation of regular blocking tables
>from non-georeferenced datasets reported by GDAL as follows:
>
>$ gdalinfo chessboard-64x64.tif
>Driver: GTiff/GeoTIFF
>Files: chessboard-64x64.tif
>Size is 64, 64
>Coordinate System is `'
>Metadata:
>  TIFFTAG_DOCUMENTNAME=/home/mloskot/data/test/sample/chessboard-64x64.tif
>  TIFFTAG_IMAGEDESCRIPTION=Sample 4-fields greyscale chessboard
>  TIFFTAG_XRESOLUTION=72
>  TIFFTAG_YRESOLUTION=72
>  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
>Image Structure Metadata:
>  INTERLEAVE=BAND
>Corner Coordinates:
>Upper Left  (    0.0,    0.0)
>Lower Left  (    0.0,   64.0)
>Upper Right (   64.0,    0.0)
>Lower Right (   64.0,   64.0)
>Center      (   32.0,   32.0)
>Band 1 Block=64x64 Type=Byte, ColorInterp=Gray
>
>and assume pixelsize_x = 1 and pixelsize_y = -1 ?

That's what I would do also. There is an extent but no (geographical) coordinate system. That's what ArcGIS does when importing an ungeoreferenced raster.

Pierre