[Gdal-dev] unable to load proj.4

[Frank Warmerdam]

Ellen De Beuckeleer wrote:
> Hi Frank, Didrik,
> 
> I added the GDAL_DATA to my environment variables and the "unnamed" 
> projection issue is solved ie. I now get:
> 
> PROJCS["WGS 84 / UTM zone 11N", GOEGCS[...], SPHEROID["WGS 84", 6378137, 
> 298.2572235630016],....]
> 
> I left out those things that are the same for what I expected. I have 
> however one more difference. What I expected is:
> 
> PROJCS["WGS 84 / UTM zone 11N", GOEGCS[...], SPHEROID["WGS 84", 6378137, 
> 298.2572235629972],....]
> 
> The difference is minimal (last 5 digits), but I wonder why this is. 
> Could this be an float/double issue, or a version difference in the 
> definition of the spheroid, or ???

Ellen,

The published value for inverse flattening I have for WGS84 from a couple
difference sources (EPSG and PROJ.4) is 298.257223563.  I'm not sure
why the spurious 0016 is being added to the end, but it is presumably
a floating point precision issue for doubles.

Why did you expect 298.2572235629972 as the inverse flattening for WGS84?

> Furthermore, is it possible to include the EPSG support files in the 
> gdal .dll file? It would be nice if I could run the program on other 
> computers without setting the GDAL_DATA variable manually.

This would be desirable, and I have considered implementing it but never
got around to it.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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