[GRASS-dev] New OpenGL options to test for native Mac and Win NVIZ

[William Kyngesburye]

On Jul 22, 2006, at 9:28 PM, Hamish wrote:

>> The nzgd2kgrid0005.gsb and ntv1_can.dat files are included in proj-
>> datumgrid-1.3 for PROJ (not GDAL).  Tho you need to install the NZ
>> grid manually with PROJ 4.4.9 (fixed in the 4.5.0 beta).
>
> Ok, I'm still using 4.4.9 (Debian packages)
>
The proj-datumgrid-1.3 is a separate download from the proj source,  
but I don't know how linux package managers deal with this.  The proj  
4.4.9 makefile doesn't know how to install the gsb file, but proj  
4.4.9 can use it.  I guess if package managers don't try to take care  
of problems like this, it makes sense to include the datum files with  
GRASS, rather than tell users to fix their PROJ installation or use a  
beta.

>> And yes, they start out binary.  I wonder if there is an endian
>> problem in these files.  I haven't heard complaints from Mac OS X
>> users.  If they are little endian, there shouldn't be a problem on
>> Intel Macs, but PPC Macs (or PPC or other big-end linux systems)
>> could have problems.  I wonder if these tables have csv/text sources
>> like the US NAD tables?
>
> We use GRASS on PPC Macs here (NZ) and I haven't noticed it being
> broken. (not to say that it couldn't be, but I'd be surprised if it
> were and hadn't bitten us yet)
>
> Yes, there is an ASCII version available from LINZ. I'd have to check
> the old correspondence to see if we have explicit permission to
> redistribute that in the same manner as the binary grid.

 From my first look at the proj grid loading, all I saw was that it  
simply dumped the datum file into memory - platform dependent.  I dug  
around some more, and it looks like it handles ntv1 (Canada) and ntv2  
(.gsb/NZ) as separate cases which take care of byte swapping issues.   
So it looks like those are OK, no endian issues.


-----
William Kyngesburye <kyngchaos at kyngchaos.com>
http://www.kyngchaos.com/

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