Hi Hermann

Thanks for offering me help, of course I am interested!

You are right, the satellite imagery on the Caribbean side of Nicaragua is terrible except for the costal areas. My friends xamanu and jaakkoh visited and help mapping Bluefields and Bilwi (Puerto Cabezas), but the coverage of Nueva Guinea is really bad.

How can you help us?

What do we need?

1. Track all your routes when you are driving, especially in the Eastern parts of Nicaragua.
2. Map important POI’s, in my opinion especially gas stations (they are rare in eastern Nicaragua), accomodation and public transportation hubs like important bus stations/airports/ports, etc. Of course you are open to map other places ;-)

What are useful mapping tools?

1. One of the best OSM apps is MAPS.ME. You can download the entire Nicaragua and it only uses about 20 MB data. You will find out that OSM is really good around Managua and the Atlantic coast.
2. A very good tool to collect data is Mapillary. Mapillary is especially useful for towns, you later can you the imagery to add the places with JOSM into OSM. Give Mapillary a try, it is really useful. For Mapillary you need a phone mount or cradle to fix it on the windshield of a car.
3. Battery packs with 10000mAh and a really good 12V car charger are incredibly useful. You never have enough power, especially the GPS and Mapillary are draining the battery of any phone very quickly

Some other helpers

1. Here is a nearly complete 1:50k topo maps collection of Nicaragua. Together with mapwraper.net you can add them as WMS layers to JOSM. Really nice.
2. The Nicaragua OSM group is very active: (http://wiki.openstreetmap.org/wiki/WikiProject_Nicaragua). If your Spanish is not very good, you might want to contact xamanu directly. He is German (and BTW I am Swiss German).

Michael

NED is used by the TopOSM project, so it is probably free like most NGA data. but NED data is, as far as I know, limited to the US, unfortunately.

I already compared more than 50 NGA maps from Central American states with Bing satellite imagery and SRTM data, and SRTM seems to be pretty good, most of the time better than the NGA maps. A lot of the NGA maps were done in the 1960’s and 1970’s and it was very complicated to get the correct height.

Thank your for your input. I already did quite some testing with rectified 1:50k NGA topo maps using different mapwraper services and Bing satellite imagery and OpenCycleMap topo layers. It is most of the time impossible to use just one source of data. For example peaks from NGA maps need to be adjusted with OpenCycleMap and satellite imagery, the quality of the NGA waterways is even worse. But the NGA maps are by far the best source for the name.

So it looks like a lot of manual work has to be done and I estimate one NGA topo map needs in average about 15 hours of work.