control point ContextCapture

Hi!

I'm testing the accuracy of the photogrammetry process. So I use GCP and check point (CP). When I use only GCP the aerial triangulation's error is not relevant and the result is good but when i use GCP and CP the CP's error is higher than GCP's error. My goal is obtain two similar error as I got with other commercial software. Maybe I did some mistakes.

How is it possible?

TEST1 

SW 1) GCP error XY -Z (0.050m - 0.070m);      CP error XY -Z(0.067m -  0.054m)

SW 2) GCP error XY -Z (0.037 0.040)        CP error XY -Z(0.050m - 0.047m)

SW 3) GCP error XY -Z (0.049 0.021)        CP error XY -Z(0.056m - 0.059m)

ContextCapture 4)  GCP error XY -Z (0.016 0.006)        CP error XY -Z(0.167m - 0.288m)

Thanks.

Maria Grazia Spera