Density grid / Heatmap from lots of GPX file

darrepacdarrepac Global Mapper UserPosts: 10
Hi

I am willing to create a density grid/heatmap based on thousands of GPX files.
When I create the density grid, it seems like it is not taking the trackpoints of each GPX files (trkpt also known as tracklog) as population field but only the waypoint (wpt) that some GPX files contain.
How can I change that? In population field, I have only the following choices and none of them correspond to the trackpoin:
<point count>
Elevation
Time

thanks

Answers

  • geomanniegeomannie Global Mapper User Posts: 225Trusted User
    Hi

    Is this what you mean? I opened numerous GPX files and then exported them as XYZ simple ASCII. If you then open the text file as ASCII selecting points only, you get a cloud of all the GPX vertices. Its then easy to create a heatmap, though I found the scaling tricky as the range was so much dominated by the points near my house. Maybe there is an easier way?
    Heat.jpg 196.5K
  • geomanniegeomannie Global Mapper User Posts: 225Trusted User
    This might be a better example of what I think you are trying to do. Can you see where I live?
  • darrepacdarrepac Global Mapper User Posts: 10
    Spotted! ;)
    Well that could make it... I understood that I had to go on the individual points way. I am currently transforming my thousands of GPX track file into GPX waypoint file to see if it works
    Thanks for the hint.


  • geomanniegeomannie Global Mapper User Posts: 225Trusted User
    Hi I didn't convert the gpx tracklogs to waypoint files, that might be a lot of work, l just opened them in GM and used the export ASCII option. It worked well to give me all the vertices.

    Cheers
  • darrepacdarrepac Global Mapper User Posts: 10
    Where can I find this ascii option (remind me something but can't find it now)?
  • geomanniegeomannie Global Mapper User Posts: 225Trusted User
    Hi, I am not at the computer just now, but as I remember, the work flow might go like this.

    1. Open all your gpx tracklogs into GM
    2. Go to file export & select vector/lidar format
    3. Scroll down the options until you find xyz (simple ASCII) text file
    4. Choose options (for a simple cloud of vertex locations exclude features, elevation etc.)
    5. Export data
    6. Open test file as data points only.
    7. Create heatmap

    Cheers
  • darrepacdarrepac Global Mapper User Posts: 10
    thanks, will give it a try!
  • darrepacdarrepac Global Mapper User Posts: 10
    More or less succeeded but everything is with the same color.... which parameters did you put in heatmap cration?
  • geomanniegeomannie Global Mapper User Posts: 225Trusted User
    Hi Darrepac
    There is no straight answer to this other than you need to understand the range of values you are getting and create an appropriate colour scale using the shader options. A good way of interrogating your data is to use the path profile tool. In the case of my data, I get one location where values are up to 4000 (the small red area n the image below which is my house), but in general the values are mostly <100. I therefore had to create an asymmetric scale bar. WIth a standard linear scale bar, everything looks blue except at my house. These images may help.

    Cheers

    Bob

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