I have a question for you folks. What kind of vertical accuracy can you achieve with say a Phantom 4 when using precise (1-2 cm) GCP taken with the right equipment? I know the initial GPS tagged image can have significant errors but can processing with hard and accurate GCP’s eliminate this large error? The use case I am looking at is evaluating volume changes on a construction site (estimating volume of dirt moved in a 2 week period) and I’m on the fence if I really need to get a drone with RTK corrected location or just get high quality control points. I know that the RTK drone will in fact give a better result, but what can I expect without it. Some of the areas of interest on the site have fill volumes down to 2", so I am not sure I would be able to effectively measure this with my current setup.