[Proj] So close -- Lat / Long to Pennsylvania State Plane North NAD27

[Jose Gonçalves]

Jeremy

I think your installation of PROJ is OK. I get the same result with the
command line (I omitted some parts which are not needed):

echo -75.921819 41.295735 |cs2cs +proj=latlong +datum=NAD27 .... +to
+init=epsg:32028
2502332.66      416669.38 0.00

The problem is, I think, with the command line. The input system is
geographical coordinates in the Clarke 66 ellipsoid, so in the NAD27 datum.
The output is a LCC projection, also based on the NAD27 datum. There is no
datum transformation, so using +nadgrids is irrelevant. Your command is
doing only a map projection, that you could also do with proj command:

echo -75.921819 41.295735 | proj +init=epsg:32028
2502332.66      416669.38

In your message you refer the NAD27 to WGS84 transformation, so it is
likely that your input coordinates are WGS84 geographical. In that case you
should use the command:

echo -75.921819 41.295735 | cs2cs +init=epsg:4326 +to +init=epsg:32028
2502234.97      416637.87 0.00

This result is much closer to what you were expecting (distance of less
than 1 metre).

> should return
>
> 2502235.76228      416637.89162

I hope this helps
Regards

José Gonçalves






2013/8/8 Jeremy Boecker <jeremy.boecker at gmail.com>

> Guys, I've tried everything suggested here in multiple variations, even to
> the point of rebuilding from the source code following the instructions in
> the FAQ, and I'm still getting the same output as is shown in my previous
> reply to this thread. I'm not sure what the difference is between what I'm
> doing and what Andre (one of the previous replies) is doing to be able to
> get the correct results. Would anyone be willing to give me a detailed
> step-by-step, starting with downloading "
> http://download.osgeo.org/proj/proj446_win32_bin.zip" and unzipping in a
> windows environment (I placed everything in C:\proj). See Andre's post
> above for the inputs and outputs. The second set of output coordinates is
> exactly what I need to get, but my output is just zeros and asterisks.
> Thanks so much folks for your help... I feel like I'm just missing
> something simple...!
>
>
> On Sun, Jul 28, 2013 at 6:03 PM, Mikael Rittri <Mikael.Rittri at carmenta.com
> > wrote:
>
>>  I think you don't have the grid shift files that are required for
>> the Proj.4 default datum shift between NAD27 and WGS84.
>> The files are called alaska and conus, and NTv2.gsb for
>> Canada, and should be in the "nad" directory I think.
>> The US files can require an extra manual command to
>> generate, if you build Proj.4 yourself.
>>
>> You can read more about this on the Proj.4 FAQ.
>>
>>  Best regards,
>>
>>  Mikael Rittri
>> Carmenta
>> Sweden
>> http://www.carmenta.com
>>
>> 26 jul 2013 kl. 20:50 skrev "Jeremy Boecker" <jeremy.boecker at gmail.com>:
>>
>>   Thank you, I tried what you said, and what I'm getting as output is as
>> follows when I run the same batch file:
>>
>>  WGS84-NAD27
>> *       * 0.000
>> WGS84-NAD27PAft
>> *       * 0.000
>> NAD27-NAD27PAft
>> 2502332.66      416669.38 0.000
>>
>>  I'm thinking my EPSG definitions might be messed up somehow... but I
>> also tried copying from <http://spatialreference.org>spatialreference.org,
>> and still I get the same output. (It seems like the 4326 EPSG is not
>> working... )  Any further ideas? Your second result is the correct and
>> expected conversion result... not sure why I'm getting asterisks and zeros
>> for the same command! :/ Thanks again for your help!!
>>
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