miluethi's Diary

NGA 1:50k topo maps into OSM

Posted by miluethi on 17 April 2016 in English.

I’m trying to define a project entering the free data of the NGA topo maps of Central America (only Nicaragua, Honduras, Guatemala & El Salvador) into OSM. Highest priority have water layers and mountains, less important would be names of settlements.

The NGA maps were all published between 1965 and 2003, most of them in the sixties and seventies. A lot of settlements are inaccurate, because they became bigger or even changed their names. Peaks and water entities are more reliable.

My idea is to get some funding and work with local universities and student to enter the data. At the moment, I’m running tests to figure out how much work in hours needs to be done. After serveral checks, I think, we have to calculate about 2 days (15 hours) per 1:50k map for mountains and water bodies.

If anybody would like to be included in this project, contact me at miluethi@rucksackradar.net.

Cheers

Location: San José del Marial, San Antonio de Oriente, Francisco Morazán, Honduras

Discussion

Comment from BushmanK on 19 April 2016 at 02:29

Did you consider using any raster-to-vector software? http://www.easytrace.com/program/et799_en - this thing is completely free and quite effective.

Comment from miluethi on 19 April 2016 at 12:54

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.

Comment from BushmanK on 19 April 2016 at 20:45

OpenCycleMap uses SRTM data as elevation data source, which is also quite far from ideal, therefore, it’s impossible to use it as completely reliable reference. NED data is much better source, but I’m not sure about usage rights.

Comment from miluethi on 19 April 2016 at 21:13

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.

Comment from danielköbsch on 1 August 2016 at 17:23

If anybody would like to be included in this project, contact me at although beeing a noob, count me in.

Comment from seäsemer on 13 September 2016 at 08:16

Hi miluethi, in about three weeks time I will be Nueva Guinea, Nicargua for some month. I have contibuted to OSM here in Germany for the last three month as kind of preparation to Nicaragua. There I would like to improve maps for the region central and south of Nicaragua. So may be I could support your project in this area as well. One problem I notice from here is that the the satelite maps for that region are horrific and much worse than in other parts of the country. Do you know something about the reason for that? Do I make some kind of mistakte?

Kind Regards Hermann

Comment from miluethi on 13 September 2016 at 17:40

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?

Track all your routes when you are driving, especially in the Eastern parts of Nicaragua.
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?

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.
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.
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

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.
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

Comment from seäsemer on 13 September 2016 at 18:42

Hallo Michael,

einstweilen danke für Deine vielen hilfreichen Tips. Mit xamanu werde ich Kontakt aufnehmen. Bin sehr gespannt auf Eure Erfahrungen und Pläne!

LG Hermann

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