First time post, looking for some advice.
I have just run a c. 500ha map with a P4P drone at 100m height and processing it through Pix4d. I have added 6 GCP’s which I have surveyed in using a Trimble Roving GPS. The GPS was used to take a number of other site measurements.
I ran stage 1.
Input the GCP’s which were in British National Grid instead of WGS84. Because the P4P doesn’t accurately measure the Z axis there was a shift between the model and the GCPs but following the guide from Pix 4D I was able to incorporate the GCPs fine and the model pulled down to the GCP levels.
I ran stage 2.
checking the model against the points on site the X & Y axis appear to be sound but the Z axis is way off?
I am not sure if it is lack of GCP’s, poor GPS data from the original photos or something I am missing. Would appreciate any help or advice anyone has?