[postgis-users] NAD conversion problem

[Richard Greenwood]

On Mon, Dec 8, 2008 at 6:08 PM, Dylan Beaudette <debeaudette at ucdavis.edu> wrote:
>> Richard Greenwood wrote:
>> The files in http://svn.osgeo.org/metacrs/proj/trunk/proj/nad/ are
>> ASCII. In the nad directory, you need to do:
>>   ./configure
>>   make
>>   install
>> to create the binary grid shift files that proj actually uses. (Proj
>> doesn't read the ASCII files). And I'm not sure that the
>> config-make-install of the proj program does the nad directory.
>>
>> Rich
>
> REALLY?
>
> I have never heard that the config-make-make install steps would not process
> the NAD grid files... Can someone verify this?
>
> Cheers,
>
> Dylan


Dylan

On my Ubuntu 8.04 with a binary proj installed from the Ubuntu repository I get:
echo '-121.000000 37.000000' | cs2cs  +proj=latlong +datum=NAD27 \
+to +proj=latlong +datum=NAD83
121dW	37dN 0.000   # obviously no datum transform

So I fetched the proj source and proj-datumgrid-1.4.zip and did
./configure make make install. But still no datum transform from my
new copy of proj. So I did:

$ nad2bin <src/proj-4.6.1/nad/proj-datumgrid-1.4/conus.lla conus

and copied it to  /usr/share/proj/ and finally I get the expected results:

$ echo '-121.000000 37.000000' | cs2cs  +proj=latlong +datum=NAD27 +to
+proj=latlong +datum=NAD83
121d0'3.704"W	36d59'59.804"N 0.000

The only copy of conus that $ locate found on my system prior to my
making it with nad2bin was in /usr/lib/grass/etc/nad/  Probably doing
$ export PROJ_LIB=/usr/lib/grass/etc/nad/ would have saved me making
conus.

Rich


-- 
Richard Greenwood
richard.greenwood at gmail.com
www.greenwoodmap.com