Author Topic: Computing GCP marking errors offline  (Read 1273 times)


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Computing GCP marking errors offline
« on: February 15, 2022, 12:13:25 PM »

I've built a web portal to mark GCPs and then consume this data to run automated processing on Metashape. But this works mostly like marking GCPs on Metashape before performing Aligning. I mean, I can't show average pixel error or lat/long/alt error when a user is marking GCPs. Showing these errors would help to mark the GCPs more accurately.

I understand that to show these errors, we first need to align/match the photos. Considering that aligning is already done, I want to show GCP marking errors by determining whether the points being marked on two images are same or not.

So far, I am able to use Metashape Python API and retrieve `rotation covariance`, `location covariance` and `transform` for each of the photos. Also, I am able to use Metashape API to compute pixel errors.

But I don't want to use Metashape API here as this is not feasible to be interacted from web UI. I need help in knowing if there is a way to use image transformation matrices (which can be exported from Metashape beforehand) to compute pixel error (given the marked coordinates from 3 or more images).