I have been using Pix4d for a number of years and have recently started getting some problems. It started off with data from our Ebee in that the pointcloud appeared to be “gridlined” and as you rotate the point cloud in the raycloud viewer the point cloud would disappear and reappear sometimes partially sometimes completely!! When I import this data into Recap though it normally looks OK, it just means you cant do flythrough videos because the image flickers in and out. Recently though I flew a mission with my Falcon 8, the data looks fine until I try to add ground control points, I get the same inverse shur error which apparently only affects the quality report but the data goes heavily gridded and patchy, when I densify it I get the very noisy, patchy and unusable model as in the screenshot below, this ONLY happens after adding ground control! I have processed it without and it works fine? The images have been geotagged by the Falcon but again I have tried with both geotagged and non geotagged images and its fine until I add the GCP’s?? I’m getting desperate to complete this data so any idea would be appreciated. The GCP’s were fired in with a total station and the quality report shows them all to be sub 10mm and there are 2 check points which show sub 10mm and had no issues on the ground so I’m confident that the control is good. The mission was a mixture of NADIR and Oblique imagery.