[GRASS5] rasters?

Glynn Clements glynn at gclements.plus.com
Mon Mar 13 07:37:58 EST 2006


Andrea Antonello wrote:

> > What are you asking, exactly?
> 
> Alright, thanks Glynn.
> 
> About two years ago I wrote the raster reading of GRASS in java for JGrass. 
> For the last to years everything worked flawless. 
> In the last months something stopped to work, i.e. when the java library tries 
> to read a raster map, it fails at the point of uncompressing the raster row.
> Since it worked properly in the past years, I expect that something was 
> changed in the GRASS libs, so I was asking if anyone knows what that 
> something could be, in order to be able to understand and fix is.

I can only think of two changes:

1. For compressed maps (integer or FP), the size of the row offsets is
sizeof(off_t) rather than sizeof(long). The main consequence of this
is that 8-byte offsets will now be more common, so if your code only
handles 4-byte offsets, it will fail more often.

2. Integer maps can be compressed using either RLE or zlib. Maps which
are compressed using zlib have a value of 2 in the "compressed" field
of the cellhd file.

-- 
Glynn Clements <glynn at gclements.plus.com>




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