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GCP Questions


I know this is probably a straight forward question, but I was wondering, if I input GCP’s after step 1, does my coordinate system before step 1 have to match the coordinate system that I input for the GCP’s? I noticed that they are the same menu pop up.

Thank you

No, you can have a different coordinate system set for your output than what your GCPs are set to. They don’t have to be the same. Though most users will set their GCPs to their desired output coordinate system.

Hi Michael Kors i can’t see my gcp’s in ray cloud map?

Hi Noel,
This is typically caused by either the order of your GCPs not correctly established or you have the wrong coordinate system set for your GCPs. When you first load your GCP file PIX4Dmapper will ask you the order of the coordinates. Either the coordinates are X,Y,Z or Y,X,Z. Double check your order. If the order is correct then you will need to specify the correct coordinate system of the GCPs. If it is not correct then PIX4Dmapper cannot place them correctly on the map.

Select Edit then select the correct coordinate system.

Michael_Krois gave two common causes of this issue (that I agree with), but there’s a 3rd one that I see more often: You changed your IMAGE coordinate system to your output coordinate system.

Does your image coordinate system have to match any of the GCP or Output coordinate systems or vertical systems?

This is where I’m confused. Do all 3 have to match? None? 2 out of 3?

Thanks in advance!

Hi bkean,
The image coordinate system should almost never be changed. Off-the-shelf commercial drones will tag the images in the WGS84 coordinate system. This includes all of DJI, Parrot, Autel, Skydio, etc. The only time you would ever change this is if you are using a custom drone that could be tagging the images in some other coordinate system.

Your desired output coordinate system and GCP coordinate system do not necessarily have to be the same. Usually they are but you can have the positions of your GCPs in any coordinate system. Just make sure it is correctly specified in the GCP manager. The same goes for your outputs. You can have Mapper output any coordinate system. You just need to specify it corrently.