Hi all,
My spec : osmium version 1.16.0
Debian 12
I have a question regarding the size difference when processing OSM data with osrm-extract.
Here is the scenario:
I start with an OSM PBF file: bourgogne-latest.osm.pbf (size: ~182 MB).
Using osmium, I filter the file to keep only certain highways for a “foot” profile:
osmium tags-filter bourgogne-latest.osm.pbf w/highway=primary,primary_link,secondary,secondary_link,tertiary,tertiary_link,unclassified,residential,road,living_street,service,track,path,steps,pedestrian,footway,pier --remove-tags w/access=no,agricultural,forestry,private,delivery -o filtered-foot.osm.pbf
The resulting file filtered-foot.osm.pbf is significantly smaller (~35 MB), which makes sense.
ls -lsH
total 211724 car :
177784 -rw-r--r-- 1 root root 182047239 Jan 13 07:13 bourgogne-latest.osm.pbf
33940 -rw-r--r-- 1 root root 34750516 Jan 13 09:46 filtered-foot.osm.pbf
I then run osrm-extract with the foot.lua profile, first on the original file (bourgogne-latest.osm.pbf) and then on the filtered file (filtered-foot.osm.pbf). After each operation, I calculate the total size of the .osrm files generated:
Using bourgogne-latest.osm.pbf
osrm-extract -p /usr/local/bin/profiles/foot.lua bourgogne-latest.osm.pbf
Total size of the resulting .osrm files: ~390 MB.
Using filtered-foot.osm.pbf
osrm-extract -p /usr/local/bin/profiles/foot.lua filtered-foot.osm.pbf
Total size of the resulting *.osrm* files: ~375 MB.
There is a ~15 MB size difference between the two outputs (390 MB vs 375 MB), even though the filtered file is specifically tailored for the foot.lua profile.
What could explain this size difference in the .osrm files generated from the original vs filtered .osm.pbf files?