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Finding distance for winding road on map
#1
I have a map image that has a very winding walking trail.  I wanted to find the distance of the trail. I was imagining using Gimp to capture the graphic of the winding trail, converting it into a line, and then stretching it out straight so I can see the distance of the trail.

What would be the steps to do that in Gimp?

Thanks,
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#2
No immediate easy solution that I can think of.

You could break the path up into layers them move and rotate to create a straight line. Going to be tedious with a long winding route.

Or this using one of ofnuts plugins "path-dump.py" Unfortunately this writes to a terminal. I assume Gimp will start in a MacOS terminal. Maybe pipe the output to a text file (gimp > file.txt) and buried in the text is the length of the path.

All in one screenshot. Traced the route with the path tool. (Stoked the path red so you can see it) Applied the plugin. Found the text file and the length (in pixels) 
Painted the magenta line in using click-shift-click for straight lines. (length shows in the notification area as you draw). 5.6 Km according to the grid.

   

I would hang on and  see if better more convenient solutions appear.
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#3
If you can view the trail on Google Earth you could use Tools/Ruler/Path and set the units to miles, kilometres or whatever. If you can make out the trail in the Google Earth images it would be a much easier way.

(10-15-2020, 10:54 AM)carljong Wrote: I have a map image that has a very winding walking trail.  I wanted to find the distance of the trail. I was imagining using Gimp to capture the graphic of the winding trail, converting it into a line, and then stretching it out straight so I can see the distance of the trail.

What would be the steps to do that in Gimp?

Thanks,
Reply
#4
I agree about Google Earth if supported by your browser.

Back to tracing with a path, then ofnuts path-edits plugin (summary option) shows the path length, without using a terminal, although it might not be that obvious.

   

edit: http://sourceforge.net/projects/gimp-pat...s/scripts/   ofn-path-edits.zip
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#5
I've always used the standalone version of Google Earth, not via a browser. It looks as though there is a version for Mac.

(10-15-2020, 02:21 PM)rich2005 Wrote: I agree about Google Earth if supported by your browser.
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#6
(10-15-2020, 04:01 PM)programmer_ceds Wrote: I've always used the standalone version of Google Earth, not via a browser. It looks as though there is a version for Mac.

A bit off topic, but  I still use a linux appimage. Do not think I am giving much away here Wink  Post-box top of the street.

   
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#7
Maybe not an answer to the question of carljong to use gimp for measuring a track, but I always use the free software MapSource from Garmin to plan my tracks. One can download and use free maps for use with this software (ex. streetmaps, velomaps,etc...). For Mac there is basecamp from Garmin but I found a freeware (now donationware) for making tracks on the Mac. If you plan to convert many tracks in the future, the use af such a program is an easy solution. Just draw the track from the image on the map and the length of the track is calculated.  

https://macdownload.informer.com/trailrunner/
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