[Xastir] DRG Error: Compression Algorithm Does Not Support Random Access

[Curt, WE7U]

On Thu, 29 May 2008, ZPO wrote:

> I did a bit more googling and found "geotiffcp" which is exactly like
> "tiffcp", but for geotiffs.  DOH!!!  I guess I should have looked a
> bit harder.  I can download the unmodified files, but the ones I tried
> didn't seem to tile together properly.

If they are in the USGS DRG standard format, they should tile
properly.  At least the 1:24k ones, which are the format the code
was optimized for.


> When you say the Xastir code is written to handle lines, do you mean
> scanlines are strips as defined in the tiff/geotiff spec?

Yes.  If you look around the USGS DRG site you can find details of
their standard format.  They have a limited number of colors and are
arranged in strips.  The unmodifed maps are in UTM projection and
have a white border.  The Xastir code will strip off this border as
it displays and stretch the map into unprojected or lat/lon
projection.

-- 
Curt, WE7U.				archer at eskimo dot com
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