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Author Topic: User defined coordinate system - select without requiring UI?  (Read 1454 times)

tristeng

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User defined coordinate system - select without requiring UI?
« on: November 25, 2020, 09:52:48 PM »
Hi there,

I downloaded the CGVD28 geoid (HT2_0.tif), and then in the Metashape application, I created some user defined coordinate systems using the tutorial:
https://agisoft.freshdesk.com/support/solutions/articles/31000148332-how-to-use-height-above-geoid-for-the-coordinate-system

For example, I created a compound coordinate system using "NAD83(CSRS) / UTM zone 11N" and then "CGVD28 height" (from the HT2_0.tif file), which I have named "NAD83(CSRS) / UTM zone 11N + CGVD28 height".

Is there a programmatic way, using the Python API, to list the user defined coordinate systems and/or load them by the name or some other ID? I know there is a way to launch a UI selection box via API, but I would like to be able to load my user defined ones without requiring any UI interaction. Or is the suggested way to dump out the WKT data for the user-defined coordinate systems, and then use that to load the coordinate system?

Thanks,

Tristen

Alexey Pasumansky

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Re: User defined coordinate system - select without requiring UI?
« Reply #1 on: November 25, 2020, 10:13:50 PM »
Hello tristeng,

If you are calling the script from the command line via -r argument, you should have the related geoid file in /Metashape Pro/geoids/ directory whereas the coordinate system can be assigned from the WKT line, for example:
wkt = '...' #just as a string with the coordinate system definition
crs = Metashape.CoordinateSystem(wkt)

In case you are using the stand-alone Python module, you should initialize the path to the geoid file in the beginning of the script (before the related coordinate system is used) by calling Metashape.CoordinateSystem.addGeoid(path) method.
Best regards,
Alexey Pasumansky,
Agisoft LLC

tristeng

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Re: User defined coordinate system - select without requiring UI?
« Reply #2 on: November 25, 2020, 10:38:19 PM »
Perfect, thank you.

tristeng

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Re: User defined coordinate system - select without requiring UI?
« Reply #3 on: November 25, 2020, 11:14:54 PM »
I did notice that since I do have the Metashape application installed, and my geoids are in the installation directory's geoids directory, I was able to load my coordinate system using Python stand alone by specifying the authority string (without first adding the geoid):

Code: [Select]
>>> import Metashape
>>> Metashape.CoordinateSystem('EPSG::5713')
<CoordinateSystem 'CGVD28 height (EPSG::5713)'>

I'm guessing that once the geoids are registered with the Metashape API (whether explicitly via addGeoid or implicitly via Metashape installation geoids directory), we can then use the authority string?

Alexey Pasumansky

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Re: User defined coordinate system - select without requiring UI?
« Reply #4 on: November 26, 2020, 12:47:36 PM »
Hello tristeng,

You can use definition with EPSG code, if the required compound system is available in registry, so it is not obligatory to use WKT line for such case.
Best regards,
Alexey Pasumansky,
Agisoft LLC