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Comparing the accuracy of an orthomosaic from Pix4D with a real accurate image

Ciao!

I am processing a project over a lake with Pix4D and I made my orthomosaic. 
I also have a very accurate image taken from an airplane and I would like to do an accuracy assessment between this real image and my orthomosiac obtained from Pix4D.

My question is that  how can I do an accuracy assessment based on this image?  I mean how can I compare my orthomosaic from Pix4D with a real accurate image in terms of GCPs, distances, etc?

I appreciate any help from you.

Pari

Ciao, 

The difference between an image and an orthomosaic is that the orthomosaic is orthorectified. This means that you can use it to measure distances and areas, which is not the case for an image. This is why I don’t understand how you would use the image to assess the accuracy of the orthomosaic. You could check if the entire area is covered, but that’s about it. Please have a look at this article to see the definition of an orthomosaic: https://support.pix4d.com/hc/en-us/articles/206799533

To assess the accuracy of the reconstruction in a project, you can use Ground Control Points (GCPs) and Checkpoints. These are reference points that are measured on the ground with an accurate GPS device. The quality report of a project will give you some indications as to the error on these points, which will enable you to assess the accuracy. 

More about GCPs in this article: https://support.pix4d.com/hc/en-us/articles/202558699
More about the quality report: https://support.pix4d.com/hc/en-us/articles/202558689