[Xastir] POSM (Portable OpenStreetMap) for APRS

[Hal Mueller]

Here’s an idea for providing OpenStreetMap map tiles in the field for APRS. It’s not the cheapest, but it’s a well supported active project. This is a follow up to the Pi 3 thread, which I didn't want to hijack. 

I attended State of the Map US last weekend. That’s the US conference for OpenStreetMap contributors, developers, and fans. 

I saw a session on a fairly new toolkit called POSM (pronounced “possum”). POSM is a freestanding Linux-based server and software to allow use and updates of OpenStreetMap in the field, without net connectivity for weeks on end. It includes complete OSM data for a region, and a full OSM stack, including the tools needed to render tiles. A POSM box also includes an http proxy and functions as an Internet hub. POSM is sponsored by the American Red Cross and saw its first large-scale deployment in the last year.

POSM’s reference hardware is a souped up Intel NUC, total cost about $350-$400 with all new parts. For remote data collection, they used Android smartphones, syncing to Intel Edison devices. The Edisons are periodically brought to the mapping hub (where the NUC lives) for data transfer: transportation is by foot, motorbike, or Land Rover. 

During the Q&A I asked about the feasibility of running POSM on a Raspberry Pi. The answer was that they had thought about it but went for higher end hardware, to make sure that it would run well. The major bottleneck is tile rendering speed (the presenter thinks their rendering style is fairly slow). It sounded like this assessment had been made based on a Pi B, not a Pi 3. Based on that, I think it's worth trying the POSM stack on a Pi 3.

How would you use POSM for APRS? Extract (ahead of time) the local OSM data you’ll need. Park the POSM box someplace within wifi range of the APRS clients. Point your client at the POSM box as an OSM tile server and Internet access point. You can even upload your OSM updates to POSM, and sync them back to OSM master when you’re connected again (think disaster response mapping).

Some links:
SOTMUS 2016 presentation: 
Summary: http://stateofthemap.us/2016/field-mapping-at-scale/
Video: https://www.youtube.com/watch?v=jDBQN5wgyr8&index=19&list=PLqjPa29lMiE3eR-gK80irr3xdUiRbIMeg

POSM source code: https://github.com/AmericanRedCross/posm

Hal
N3YX