Dear Forum,
I'm still on trainer wheels with metashape (v1.6) but after dozens of iterations to troubleshoot a problem ... i think i need some advice.
I have faithfully followed the Agisoft 'Tutorial for beginners: Orthophoto and DEM generation (with GCPs) ..' and a number of (excellent) video tutorials by SkySurv.
My test data set comprises imagery captured with a dji mavic pro ... and a web of rtk GCP,s captured using an altus aps3g base/rover gps. The photography have 80% forward and side overlap, is I assume in wgs84 . Flying height was ~30m above ground on a perfect day with little or no breeze. The GCP's are in GDA/94 UTMS (zone 55) (SE Australia).
Briefly i can get a very good result if i use a small subset of my photos (76) and the GCPs (6) - but when I try and emulate the workflow with my whole data set (280 photos and 15 gcp's) I can't get a usable solution.
The first manifestation things are array is after i align the 280 photos .. there is an east west offset (about 27m) in the 'cameras' and the sparse point cloud. When I bring in the GCP's that offset persists.
I have tried both transforming the imagery to GDA and also leaving it in wgs84, i have also tried explicitly defining the different image and gcp coordinate spaces.
I can import my gcps as a kml into google earth and they align perfectly .. so i think the error is coming from the photography.
I have attached 4 images that i hope explain the problem. 1) a nadir view of the basic camera model, 2) screen view of the gcp import window, 3) ortho view of the gcp markers and the cameras (is a sensible relationship), 4 ) the camera's and gcp's atop the cloud with the 27m offset shown
thanks in advance
Guy Byrne
(Geoscience Australia)