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GCP Marking Best Practices

When working with GCPs, is it better to mark then in absolutely all images that they appear in, or only those that are high quality/clear?

I would expect only high quality, but after experimenting on a project, it seemed like when including GCP in more images (even if they were low quality/blurry/distorted), the overall error of GCPs (and other checkpoints in the project) went down.

Example below- when the GCP is at the extreme edge of the camera frame it can get distorted.

Hi Ben,

It is good to mark only on the images where the GCPs are clearly seen and can be marked accurately. Mark 8-15 quality images where your targets clearly exists (and you can identify the center of your target at the pixel level). The zoom level at which GCPs are marked has an impact on the GCP RMS error obtained in the Quality Report, so ensure to mark them at a high zoom level. Usually, the higher the zoom level, the more precisely the GCP is marked. These GCPs will have more impact on the reconstructed model than GCPs marked in a lower zoom level and lower error values are expected for those GCPs. For example, when GCPs are marked without zooming into the images, the GCP error can be 10 times higher than when GCPs are marked by zooming into the images.

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