Ortho and DSM not Georeferencing

Answered

Comments

7 comments

  • Avatar
    Wishgranter
    Hi Alvaro
    Look at the WORKFLOW -> SETTINGS -> COORDINATE SYSTEMS if you set the proper OUTPUT coordinate system. Then when you export a model, you can select the exporting option.
    As for the ORTHO data, please look at the ORTHO PROJECTION when the file is generated to check if you have a proper PROJECTION SYSTEM.

    When everything is set properly, as mentioned above, and you still get these issues, look if you export the TWF files next to the ortho data. the TWF file specifies the COORDINATE SYSTEM, so it could be the GIS importer compatibility issue.
    What particular GIS software are you using ?
    0
    Comment actions Permalink
  • Avatar
    peterwatson
    I am having a similar issue. Coordinate system is set correctly for output, everything looks great in RC, minimal positional errors for ground control points but the orthophoto is not in the right spot when exported.

    Project is about 1000 photos, about 20 ground control points- most with very high accuracy position and level- either static GPS or total station traverse for X,Y and digital level for Z (so maybe 5mm error at worst) Couple of GCPs only RTK GPS (so ~20-30mm error)

    When I bring output into GlobalMapper it looks great (and coordinate system is correct) but then when I overlay ground control points from survey file, their position is not quite correct- not major errors, but in some cases up to 800mm off for position, Doesn't seem good enough when I consider the minimal errors reported for control in RC.

    I have rectified the output in Global Mapper and it's now spot on, but I don't think I should have to be tweaking the output from RC to get it correct?!?
    Image
    0
    Comment actions Permalink
  • Avatar
    Alvaro
    I'm using QGIS and also tried with GvSig, on both the coordinates and measurements are not correct.

    Already tried to change the output of the project and also the ortho. And the results are the same.
    Not sure if the tfw file is being correctly loaded.

    Can you suggest an free GIS that works good with RC.
    0
    Comment actions Permalink
  • Avatar
    Wishgranter
    Hi Alvaro and peterwatson
    Is it possible to get the dataset ( images + RC project ) from you to inspect this behavior ? to check if it is a workflow issue or something else. We have positive results as for precision etc. in many other projects + add short description of the issue and what software you used for the GIS data processing
    Send it to milos.lukac@capturingreality.com, best if the data are packed so that I can download and process it easily.
    0
    Comment actions Permalink
  • Avatar
    HeritageExplorer
    Same problem here.
    My input : a set of UAV pictures, whose initial GPS lat/lon in the exif overlay nicely with a satellite view.
    The output : after alignment, there seems to be an average error of a few meters (in Capturing's "Registration Pose"), which is relatively understandable considering the GPS accuracy. However, when i export the ortho, there is a 20 m shift in X, 220 m shift in Y with the satelite view. The exported aligned images lat/lon show the same displacement. Same offset happen with coordinates of the point cloud itself exported and loaded in CloudCompare for example.

    In Capturing's Prior Pose tab, the coordinate system is set accordingly, X and Y confidences are set at 1, and Z at 0.8
    Are these absolute accuracies ? (1° accurate for plani and 0.8°for alti ? 1 and 0.8 meters ?)
    Do you think this is a misuse of the alignment module or rather from the import ?

    Best regards
    0
    Comment actions Permalink
  • Avatar
    Wishgranter
    Hi Yves

    The output : after alignment, there seems to be an average error of a few meters (in Capturing's "Registration Pose"), which is relatively understandable considering the GPS accuracy. However, when i export the ortho, there is a 20 m shift in X, 220 m shift in Y with the satelite view


    In what projection system are the data exported and compared to "satelite view" you mean Google maps or ?
    Do you have any precise GPS coordinates ( say under 5m precision if not better with D-GPS )
    Can you make some screenshots so we can better understand what is happening there ?

    In Capturing's Prior Pose tab, the coordinate system is set accordingly, X and Y confidences are set at 1, and Z at 0.8
    Are these absolute accuracies ? (1° accurate for plani and 0.8°for alti ? 1 and 0.8 meters ?)


    These are good values, Z height is "always" with lower precision, mostly if that are ordinary GPS precision data and not D-GPS measured
    0
    Comment actions Permalink
  • Avatar
    Götz Echtenacher
    Hey guys,

    is it possible that the point offsets are linear (if there are several in one orthe) and also limited to one ordinate (X or Z)?
    Because I am sometimes having difficulties with randomly distorted orthos, they stretch in one direction.
    The trick is to activate the faulty ortho in RC and then change the Ortho Pixel Size again to your desired value and see if the output resolution changes. Just a thought...
    Here the link:Bug 3805: Pixel number changes in orthophoto
    Towards the end of the topic the numbers get more significant.
    0
    Comment actions Permalink

Please sign in to leave a comment.