How to obtain or create a .prj coordinate system syntax file

To work with a coordinate system that does not exist in the Pix4D database, a .prj file needs to be imported in Pix4Dmapper. The .prj can be either downloaded online or manually created. 

 

Download online:

The following link has .prj files for almost all common coordinate systems: http://spatialreference.org/.

To obtain the .prj file:

1. Open http://spatialreference.org/.
2. On the top right, on the search text box, type the desired system and click Search.
3. Click the desired coordinate system (if it is not listed navigate via the Next page link).
4. Click the link .PRJ File, the browser starts downloading the file.

 

Manually create a .prj file:

If a local coordinate system is used:

1. Create with notepad a file using the format:

LOCAL_CS["Non-Earth (Meter)",LOCAL_DATUM["Local Datum",0],UNIT["m",1.0],AXIS["X",NORTH],AXIS["Geocentric Y",EAST],AUTHORITY["EPSG","262148"]]

2. Save it as .prj.

 
Example: LOCAL_CS ["WGS 84",LOCAL_DATUM["World Geodetic System 1984",SPHEROID ["WGS84",6378137.0,298.257223563,AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0.0,AUTHORITY["EPSG","8901"]],
UNIT["degree",0.017453292519943295],AXIS["Geodetic latitude",NORTH],AXIS["Geodetic longitude",EAST],
AXIS["Ellipsoidal height",UP],AUTHORITY["EPSG","262148"]]
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3 comments

  • Raphael Atimbire

    Hello,

    Thanks a lot for this information. I am currently faced with a problem. I get variations in the raycloud formed when I use Pix4D's listed coordinate system ( Leigon / Ghana Metre Grid ) as compared to when I use a prj file of the same coordinate system from spatial reference.org 

    I am able to tell the difference because the GCPs I import end up on different positions of the project area each time.

    Could you kindly help me figure this out?

    Ideally, I would want to generate a prj file that would produce identical results with that listed in Pix4D's database.

  • Blaž (Pix4D)

    Hi Raphael,

    I had a look at the Leigon / Ghana Metre Grid coordinate system definition in Pix4D and it indeed differs a bit from the one on spatialreference.org.

    If you would like to use the coordinate system as defined in Pix4D, it is possible to use the project_name_wkt.prj file generated in the params folder. The .prj file is available when the output coordinate system is selected as Leigon / Ghana Metre Grid and Step 1 is completed. 

    Best,

    Edited by Blaž (Pix4D)
  • Raphael Atimbire

    Hi Blaz,

    Thanks a lot for the help. I located the wkt.prj file in the params folder just like you said and it works perfectly.

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