Generates contour mbtile files from DEM files. For both, metric and imperial.
The mbtile file then can be used with maplibre-gl-js and mapbox-gl to render the elevation contour lines in a vector map.
Based on the work of nst-guide https://github.com/nst-guide/terrain Converts each DEM file to a mbtile file and then merges all mbtile files into a single file. This allows parallel processing of the DEM files, which speeds up everything and doesn't need much memory, compared to first stitching together the DEM files to a huge vrt and then processing this file in one go. Downside is that at the border of the DEM files the contour lines are overlapping.
# clone repository
git clone [email protected]:CramericaIndustries/vector-terrain-cli.git
cd vector-terrain-cli
# build
npm run build
# process all hgt files in the '/data/unzipped/karibik-dem3/' directory
# the resulting 'merged.mbtile' file will end up in the output directory
./build/cli.js contour --threads 16 --debug ./output ../data/unzipped/karibik-dem3/*.hgt- use the
--threads xcommand line argument to determine how many dem files will be processed in parallel - if the execution was interrupted, after restart the cli won't process already processed files
If tile-join fails after a while with the following error message: "unable to open database file"...
It probably is because you are trying to merge more files than the system can open at the same time.
Check ulimit -n to see how many files your system allows you to open in parallel.
You can increase the limit by first editing vim /etc/security/limits.conf
#<domain> <type> <item> <value>
* hard nofile 100000
This will allow to increase the limit to 100.000 files. After that you can set the limit by again using ulimit: ulimit -n 100000.