[Liblas-devel] Writing VLR?

[Martin Vales]

>
>
> I'm not too familiar with proj definitions but it seems that this:
>
> +proj=tmerc +lon_0=-81 +k=0.9996+x_0=500000 +datum=WGS84
>
> is really just an alias for:
>
> +proj=utm +zone=17 +datum=WGS84


UTM use the same method than transverse mercator. UTM is a nice way to talk
about transverse mercator. For example geotrans when call to UTM internally
prepare the parameters of the equivalent transverse mercator.
In quamtum gis you have many definitions of projections in the proj format
by countries:
http://www.qgis.org/

In proj library you have also many definitions in that format but in a
unique text file.
http://download.osgeo.org/proj/proj446_win32_bin.zip

regards.



>
> It probably doesn't matter but the latter seems more readable. On the other
> hand most users should know -81 =  zone 17.
>
> Thanks again
>
>
>
>
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