[postgis-devel] [PostGIS] #1114: [raster] ST_Resample

[PostGIS]

#1114: [raster] ST_Resample
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 Reporter:  dustymugs       |       Owner:  dustymugs            
     Type:  task            |      Status:  new                  
 Priority:  medium          |   Milestone:  PostGIS Raster Future
Component:  postgis raster  |     Version:  trunk                
 Keywords:                  |  
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Comment(by pracine):

 Replying to [comment:15 dustymugs]:
 > Replying to [comment:13 pracine]:
 > \> Shoul I understand here that it is not possible to resample to a
 rotated grid using GDAL?
 > >
 > > I agree that it is not clear what should be the desired behaviour with
 the first series of variant when the raster is rotated... If the raster is
 not rotated only changing the pixel size make sense (variant 1 and 3). You
 want the upperleft corner to stay the same. But what if the raster is
 rotated? I would solve this like this:
 > >
 > > 1) Take for granted that when no skewx and skewy are provided they are
 0 and hence we lose the rotation if there was one.
 > >
 > > 2) Add a variant to the first series taking skewx ans skewy (like in
 the second series) allowing to specify the new rotation if we want to keep
 one.
 > >
 > > Do you want me to update the specs to reflect that?
 >
 > No.  You can resample to a rotated grid as you can specify the output
 raster's geotransform, which gets used in the third stage of the
 GDALCreateGenImgProjTransformer2 function.
 >
 > http://gdal.org/gdal__alg_8h.html#94cd172f78dbc41d6f407d662914f2e3
 >
 > I think the desired behavior is to maintain the skew of the input
 raster.  Only by specifying skew parameters should the resampled raster's
 skew change.

 Actually in all the ST_Resample signatures, pixelsize, pixelsizex and
 pixelsizey should be renamed scale, scalex and scaley. For me if you don't
 specify skewx and skewy it mean you want them to be set to 0.

 > Is it possible for you (or anyone else for that matter) to send me a
 small set of skewed rasters?  I could use landsat imagery but I'm looking
 for something more manageable.

 Can't you just do:

 CREATE TABLE skewedrasttable AS
 SELECT ST_SetSkew(rast, x, y)
 FROM yourtable

 Much easier than in ArcGIS...

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1114#comment:17>
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