Topics

1

General / Ground Control Error Reporting

« on: August 06, 2014, 03:31:54 PM »

I've read through several of the forums regarding how errors for ground control points are reported and still don't quite understand how the errors are being calculated.

From what I've read, the total error reported at the bottom of each column is essentially RMSE ("square root from the sum of squares and that's all is divided by the number of GCPs").  Is this correct? 

I've put my GCP error values into an excel table and no matter how I try to calculate total error for each column (x,y, and z), or the error values in the 5th column, I can't get the numbers even close to matching.

Would someone please help explain how PS calculates these values?

Thanks in advance.

2

General / Model upside down and tilted

« on: July 28, 2014, 08:08:50 PM »

I'm using aerial photos from a mini UAV in Photoscan Pro to make a surface model of a group of trees but the dense cloud keeps coming out upside down as well as tilted (rotated).

The flight controller on the mini UAV doesn't allow me to download camera position data, but I did lay out 10 GCP targets around my stand of trees that I took relatively accurate (~1m horiz/vert) GPS points with.  Have followed the Orthophoto and DEM Generation (with GCPs) tutorial quite closely to  align photos without camera positions, place markers on my GCPs, and load GCP coordinates, set coordinate system, etc...

I've checked several times and I'm quite certain that I haven't confused my easting/northing coordinates when I import my ground control coordinates text file.  I have also made sure that the red-colored side of my bounding box is located underneath my model.

Because of the height of the trees in the aerial imagery, in a few photos some of my GCPs on the ground are obscured by the trees. In these images, the marker in the Ground Control workpane for a certain GCP I'm working on will be on top of the trees. I'm starting to think that this might be contributing to why my model is tilted, but having a hard time understanding why it appears to be mostly upside down.

Should I be disabling the GCPs that have been obscured in some of the images, or disabling the cameras that have hidden GCPs in them?  Is there a way to delete a single marker point from a single camera when it's hidden by the trees?

Thanks in advance!