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Arbitrary Coordinate System & GCP's

I’m having issues with the Arbitrary Coordinate System process.

We have guys that are using Total Stations in the field and shooting points that include 6 GCP’s.  Then days later, we are flying the site.  I’m attempting to import the total station points into the point cloud as GCP’s.  I successfully imported them but when I went to reoptimize my scene flipped the Z axis and now everything is upside down.  Where did I go wrong?

The total station is marking it’s location as X: 0, Y: 0, Z: 0.



Hi Hunter, 

How have you imported the GCPs? i.e. through the rayCloud or in the GCP/MTP Manager.

The first thing I would check, if you imported the GCPs through the GCP/MTP Manager is if the coordinates of your GCPs were imported in the right order, i.e. X, Y, Z or Y, X, Z. 

If you added them through the rayCloud, I would make sure that the coordinates were assigned to the right feature in the project as the street can look very similar.

If you could share the quality report and log file of your project we could find more potential issues. 

Thanks! Keep us posted.

I’m importing through the GCP/MTP manager.

We’re using total stations on an arbitrary coordinate system; we shoot about 100 points or so with 6 of them marked for GCP’s.  I’m importing images using the geotagged photo’s coordinate system (not RTK), then importing the total station GCP’s in an arbitrary coordinate system with the basic editor.


The end goal is to have the two sync up in a 3rd party software used for crash reconstruction.  How do I go about linking the pix4D point cloud with the GCP’s together, then exporting the point cloud and the gcp/mtp’s into a 3rd party software such as Trimble Reveal?



It looks like the workflow you follow (image geolocation, basic editor,…) is correct. The only thing that could flip the project is the wrong coordinate order. Make sure that you Process > Reoptimize the project once the GCPs were added. 

What file format do you need to import in Trimble Reveal?
Here is a list of output formats you can generate for the point cloud: