(This is a re-post from the general discussion area where I have requested that the original message be deleted when I discovered this more relevant section of the forum.)

Hello, I recently discovered Marble maps and I'm thoroughly enjoying the learning experience. I am trying to view FAA sectional charts in Marble maps. They are freely available here: https://www.faa.gov/air_traffic/flight_ ... ducts/vfr/

I downloaded the GEO-TIFF file for one chart, converted it to tiles using gdal2tiles.py, copied a base tile from the openstreetmap folder in the marble directory structure, created the DGML file, and tried to load it in Marble but with no success. The entry for the map shows up in Marble but no map is displayed when it is selected.

The directory structure can be viewed here: http://flt.l5.ca/maps/sectionals/ Within that directory structure are HTML files that display the tiled map as an overlay on several mapping services. You can try this one for example and you will see the tiled map correctly overlayed: http://flt.l5.ca/maps/sectionals/openlayers.html . So the chart seems to have the proper structure. The directory also contains the source files (mtl*) and the files generated by gdal2tiles.py.

However the map doesn't show up in Marble and HTTP server logs are showing requests for tile files that don't exist. Excerpt from log below.

Any help to get this to work in Marble would be very much welcom. Thank you.

Code: Select all

127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /9/152/175.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/301/349.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/302/349.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/303/349.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/304/349.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/301/350.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/302/350.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/303/350.png HTTP/1.1" 404 -
127.0.0.1 - - [23/Jan/2017 21:46:29] code 404, message File not found
127.0.0.1 - - [23/Jan/2017 21:46:29] "GET /10/304/350.png HTTP/1.1" 404 -


After some investigation, I discovered that the map shows up at the right longitude but at the opposite latitude. The map I am using at the address above is the Montreal sectional chart (~45N latitude) but it shows up in South America (~45S).

How is it possible that Google Maps and other services display it in the right area and only Marble Maps shows it on the wrong hemisphere?

Hi, gdal2tiles gives you a TMS scheme, which is different to the (OpenStreetMap) OSM scheme. The main difference is that the numeration of the Y axis (latitude) goes from south to north in TMS whilst it goes from north to south in the OSM.

Marble needs the OSM scheme. To create the tiles correctly you could either manually invert the numeration or use this version of the gdal2tiles.py file which gives you the OSM scheme tiles.

http://gisfile.com/user/admin/gdal2tiles.py

Best regards,
Victor

Thanks for the response, that's exactly what the problem was. I should have come back here earlier to post the solution.

I changed the source code of gdal2tiles.py to generate the proper file names. I got the idea from jeffaudi on GitHub: https://gist.github.com/jeffaudi/9da77a ... 2tilesg-py