Our team is trying to image plant beds in a greenhouse to monitor plant growth and health in contained environment. To this end we have built a gantry system from which we hang our RGB and NIR cameras. As the drone flies, the gantry rolls. Overlap is good. However, artefacts are frequent in the final orthomosaic because all the images have the same geolocation and we have no GCPs. The plant bed measures roughly 2 metres wide by 6.45 metres long. I am wondering if we can create a custom spatial reference so that we can use GCPs and eliminate the artefacts. It is important that perspective is corrected; therefore, photo stitching is not a solution for this project. I thought about the possibilities of selecting arbitrary projection for both the images and the GCPs or using GCPs as tie points but not sure that would help at all. Please advise.