[Liblas-devel] Writing VLR?

[Howard Butler]

On Nov 3, 2008, at 10:44 AM, Martin Vales wrote:

>
>
>
> 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
>

Yep, proj is providing a dictionary to map +proj=utm +zone=17 into  
+proj=tmerc +lon_0=-81 +k=0.9996+x_0=500000.  The coordinate systems  
aren't transitive because proj doesn't do a reverse dictionary lookup  
to go from +proj=tmerc +lon_0=-81 +k=0.9996+x_0=500000 *back* to  
+proj=utm +zone=17.