Greetings, The relevant code is located here https://github.com/qgis/QGIS/blob/master/src/app/georeferencer/qgsleastsquares.cpp
Hope this helps. Alex Le lun. 2 nov. 2020 à 16:18, Randal Hale <[email protected]> a écrit : > Good afternoon QGIS People > > I received a question on RMSE errors in georeferencer and after talking to > Ethan about it I realized I have no clue what I'm talking about. How would > we go about calculating an RMSE for a rectified image in QGIS? > > I've cc'd ethan on this so he can chime in also. > > Thanks > > Randy > > > -------- Forwarded Message -------- > Subject: Georeferencer Plugin Help - QGIS > Date: Fri, 2 Oct 2020 15:27:13 +0000 > From: Ethan Cissell <[email protected]> <[email protected]> > To: [email protected] <[email protected]> > <[email protected]> > > Hi Randal, > > I have a question about the usage and outputs of the Georeferencer Plugin > in QGIS, and thought, given your expertise, you might be able to directly > help, or point me in the right direction. > > I am a Ph.D. candidate in Ecology and Evolution at Florida State > University applying spatial techniques to study the dynamics of benthic > cyanobacterial mats on coral reefs. This past summer, I photographically > tracked individual cyanobacterial mats in which I had placed plastic stakes > as ground control points for later image rectification. I am trying to > essentially create image stacks, so that I can parameterize a generalized > additive mixed effects model that accounts for the inherent spatial > autocorrelation and includes a parameter with occupation at the previous > time-point explicitly included to hopefully model the population dynamics > of this system. > > Thus, a quantitative understanding of the error in my alignment is > absolutely critical to the downstream conclusions (especially for informing > my resampling to larger grid size to account for error in my alignments). > I am using QGIS for obtaining all raw data from these photos (scaling, > rectification, classification, resampling), but I am stuck at the > rectification step. I am using the “Georeferencer” plugin to accomplish my > alignments, but I have received mixed advice on how to interpret the > residuals output on the GCP table in the Georeferencer window (screenshot > below). The documentation for this plugin seems to indicate that the far > right column (Residual) is actually a per GCP RMS error. > > Can you tell me how to interpret these errors/how to obtain a total RMSE > error for the image alignment (i.e. not just per GCP error, but total error > for each image)? I have been told to sum all of the values from the > residuals column and take the square root of that raw summation. Is this > correct? > > Many thanks in advance. I apologize for the lengthy email, but I wanted to > establish the motivations for this project so that you would have more > context for the goals of the alignment. > Any and all help here is greatly appreciated. > > > > > Best, > > Ethan C Cissell > —————————————— > Ph.D. Candidate - McCoy Lab > National Science Foundation Graduate Research Fellow > Florida State University > _______________________________________________ > Qgis-user mailing list > [email protected] > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
_______________________________________________ Qgis-user mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
