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Author Topic: Defining New Coordinate System in PRJ File  (Read 3421 times)

claranine

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Defining New Coordinate System in PRJ File
« on: July 12, 2016, 02:53:48 PM »
Hi all,
          I'm an agisoft newbie here looking to define a custom coordinate system and am running into difficulty getting the provided PRJ file to work (See attached).

When I remove the PROJCS tag from the PRJ file below I am able to get the coordinate system to load however when I attempt to apply it I get a "transform not supported" error. I've tried copying the appropriate values into a saved prj file from Agisoft however so far I continue to get the same error.

Is there something obvious here I'm missing? Any help would be greatly appreciated.

Cheers

Alexey Pasumansky

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Re: Defining New Coordinate System in PRJ File
« Reply #1 on: July 12, 2016, 04:22:41 PM »
Hello claranine,

Convert option (transformation of the coordinates from one system to another) are only possible if TOWGS parameters are defined for both systems used in conversion - original and target.

As for the mentioned system, we haven't found any information about projection specified in the file: "xrail90_Azimuth_Center"
Best regards,
Alexey Pasumansky,
Agisoft LLC

claranine

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Re: Defining New Coordinate System in PRJ File
« Reply #2 on: July 12, 2016, 04:58:17 PM »
Hi Alexey,
                 Thanks for your reply. Could you possibly give me an example of correctly defined TOWGS parameters and what information I require to define them? The original coordinate system is WGS84 so that end is sorted, I was of the understanding that the information in the PARAMETER tags were sufficient to define a translation from WGS to Xrail90.

My understanding on these parameters is rudimentary however are you saying that the projection specified: "xrail90_Azimuth_Center" is invalid? Would finding the transformation parameters from something like the Transverse_Mercator projection help?

Cheers!

Alexey Pasumansky

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Re: Defining New Coordinate System in PRJ File
« Reply #3 on: July 12, 2016, 05:21:38 PM »
Hello claranine,

Do you have any reference for Xrail90 projection? We couldn't find that anywhere. Changing PROJECTION section contents to Transverse_Mercator would help to load the PRJ file, however, I'm not sure if it will be valid coordinate system, since I haven't found any information about this system yet.

TOWGS84 section usually contains seven parameters transformation. As a reference you can use almost any coordinate system saved from the supported list.
Best regards,
Alexey Pasumansky,
Agisoft LLC