Auto import/rectification of 1000's of images

vschmidtvschmidt Global Mapper UserPosts: 3
edited August 2013 in Raster Data
Hello,

I have 1000's of jpeg images that I want to import into Global Mapper. I have navigation for each of them. The images are taken from an underwater robot and I am planning to correct for the vehicle's heading, pitch, roll and altitude above the bottom. The math is more or less straight-forward and my thought was to generate a gcp file for each image with control points for each corner of the image hoping this would allow a seamless import.

I'm still working on my code to do this but before I got too far I had two questions I was hoping someone might be able to answer.

First, is writing gcp files the best way to do it or is there another way that might make more sense? For example, is it possible to write a single file that has the jpeg path and filename and all the necessary control point information for each file on each line? Or is there a smarter way altogether?

Second, the gcp files use (imo) an unfortunate syntax, in that they write out the lat/lon of each control point in decimal degrees and then in deg, min, sec. This alone would not be a big deal (although tedious) but the degree symbol (small raised circle) is used in the files generated by global mapper itself. Does anyone know how to programmatically generate that character. My knowledge is limited to standard ASCII.

One last thing, in the gcp files generated by global mapper are a few fields which aren't clear to me. They fall between the the point name and the deg/min/sec location information. Does anyone know what these are?

Ok, now one last thing. Is it possible to generate a gcp file with only the gcp point information and the point name an omitting everything afterward? This would simplify things greatly.

Ok. That's it. Thanks in advance,

Val

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited August 2013
    Val,

    I think the GCP files are the way to go, but you don't need to use degree/minute/second, any coordinate format will do. They just have to look like the following for each line:

    pixel_x,pixel_y,ground_x/lon,ground_y/lat

    You don't need the name or the other stuff on the end. And you can just enter decimal degrees for the ground X and Y, or if you have the degree/minute/second just separate them with spacings. Global Mapper will read them in lots of ways. For example a point at the top-left pixel at 39 deg 30 minutes 5 seconds North and a longitude of 93 West could be stored as:

    0,0,39 30 5N,93W

    If you have the .gcp file along with each image it should automatically be found and used.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
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