[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?

>> There is no similar example on the vector side as there
>> is no (need for an) extent in the geometry_columns table.
>
>That's unclear how it relates to my question.

I guess I misunderstood... You mean what to put in the raster_columns's "extent" column if there is no raster in the 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.
>
>Givne what GDAL reports for chessboard-64x64.tif, could you explain
>what values you put into RASTER header in each row (tile) and
>what goes to RASTER_COLUMNS, etc.?

In the raster header (there should be only one tile, right?):

scaleX = 1
scaleY = -1
ipX = 0.0
ipY = 0.0
skewX = 0.0
skewY = 0.0
srid = -1 (or 0?)
width = 64
height = 64

In RASTER_COLUMNS:

srid = -1 (or 0?)
pixel_types = 8BUI
regular_blocking = true
pixelsize_x = 1.0
pixelsize_y = -1.0
blocksize_x = 64
blocksize_y = 64

No?

Pierre