The image sampler will probably be lost in my modified copy of your file. Old GH bug. You must copy/paste and reconnect the one you have. Your Srf param was not internalized so I added a PlaneSrf instead. That needs to match the image size ratio, and ideally allow changing resolution while keeping the ratio of horizontal to vertical the same (not implemented below).
ImageSampler_GarfieldStation_CTA_2018Mar21a.gh (21.6 KB)