[Proj] ITRF96/UTM 36N conversion

fernandohoze muranyum at yahoo.com
Sat Aug 8 12:12:09 PDT 2009



José Alberto Gonçalves wrote:
> 
> In order to convert UTM-36N to long-lat with output in decimal degrees you
> can use the following PROJ command line:
> proj -I -f "%.9f" +ellps=WGS84 +proj=utm +zone=36

Thank you all for your replies. I tried the command José wrote (with -r flag
- thanks Gerald) and it worked well. The command also works without
reformatting the input.

About calculating distance between two points... José, I examined the
program you recommended but and I have some results but I need to make sure
that they are correct. Here is what I did:

First of all, here are the input points:

4415488.923061 481668.789218
4415490.272973 481668.977703

I found latitude and longtitude using the following command:

proj -r -I -f "%.9f" +ellps=WGS84 +proj=utm +zone=36

Results:

32.785593500    39.889265833
32.785595667    39.889278000

So, when I wrote these into Google Maps (in reverse order,) it correctly
showed the points:

39.889265833   32.785593500
39.889278000   32.785595667

Then, I executed the following geod command:

geod +ellps=WGS84

As input I wrote the above numbers. As output I received the latitude and
longtitude in degree/minute/second format:

39d53'21.357"N  32d47'8.137"E   180d
39d53'21.401"N  32d47'8.144"E   180d

Then, I executed this command for distance calculation:

geod +ellps=WGS84 -I +units=km

And entered the above coordinates as input:

39d53'21.357"N  32d47'8.137"E   39d53'21.401"N  32d47'8.144"E

The result was:

6d59'12.829"    -173d0'47.167"  0.001

0.001 at the end of the result tells that the distance is around 0.001 km
that is 1 meters. So, I tried the command with +units=m and the result was

6d59'12.829"    -173d0'47.167"  1.368

That is 1.368 meters, which seems to be correct. I did the same calculation
using  http://www.movable-type.co.uk/scripts/latlong.html this web page  and
the result was 0.001369 km. So, I guess I used the correct commands. The
inputs I used for the web page were like that:

Lat 1: 39 53 21.357N
Long 1: 32 47 8.137E
Lat 2: 39 53 21.401N
Long 2: 32 47 8.144E

There is one problem here that I don't get. When I use cm or dm for +units
option, I still get 1.368 insted of 136.8 for cm and 13.86 for dm. Actually,
if I don't use any +units option, I still get 1.368 as the result. Is there
something wrong with the command I use or am I missing something?

I also tried everything above with the following inputs:

4415475.022910	481656.729116	918.850000
4415473.636002	481656.540539	918.850000

And in the end I got 1.195 as the results, which is reasonable. The web site
gave 0.001194 km.

I tried to write everything I did step by step. Could you please tell me if
above calculations are correct or not. Also I would appreciate if you tell
me a command that would do all the computation above.
-- 
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