Before:
- Choose an area depending on number of participants and time.
- Decide on a date. Friday evening is recommended.
- Make a pie.
- Prepare pie for uploading to MapCraft and upload it.
After:
- Create before-after animation
- Create a diff image and HTML
- Filter images and create a progress video
Download a region from GIS-Lab or Geofabrik, before the mapping party and after. Using a mapping party area polygon, cut your region for both dates:
osmconvert region-before.osm.pbf -B=party.poly -o=party-before.osm
osmconvert region-after.osm.pbf -B=party.poly -o=party-after.osm
Install Perl and GD library (for Mac OS, perbrew is recommended). Download osmdiff.pl
and place osmgraph.pm into OSM directory.
(Actually, it has been uploaded to this repo, so never mind).
Then:
perl osmdiff.pl party-before.osm party-after.osm party-diff.htm party-diff.png 2048
The latter number is an image width. The default value is 1024.
Identify two points of time before and after the mapping party. But if there were remarkable changes during the event, like adding or removing a landuse polygon covering most of the party area, consider using images on one side of that change.
convert -delay 150 before.png after.png -layers Optimize before-after.gif
convert -delay 150 before.png after.png -crop 1024x700+0+100 +repage -layers Optimize before-after.gif
Just run filter_and_label.sh (requires imagemagick). The current directory must contain timelapse PNG images.
The script will move duplicate images to a separate folder, and then create labelled images in a new directory.
After that:
ffmpeg -framerate 5 -pattern_type glob -i '*.png' -c:v libx264 -pix_fmt yuv420p party.mp4