OpenGeofiction

Topo Layers

Posted by SwissCrusader on 15 September 2021 in English (English).

I am planning to create a small topo layer area, this autumn or this winter. Currently, the only documentation I’ve found is on the old wiki archive : https://old.opengeofiction.wiki/index.php/OGF:Making_a_topo_layer and the related Talk page.

So I understand that the described method is to draw contour lines, with contour=elevation and ele=N on a separate file, then send it to the admin team.

  1. Will there still be this possibility in the future? Is it worth starting ?

  2. Is it mandatory to map one curve every X meters (i.e. 10 meters), or not ?

  3. Is drawing by hand on JOSM the only method, or did anyone use another method, like heightmap images ? On some countries with topo layer coverage, there are quite a few artifacts that are typical of some computer-generated heightmaps like here: https://opengeofiction.net/#map=12/-20.3116/122.2140&layers=V

  4. Quite technical question: If I map i.e. a rectangle on my country, it will create an artifact at the border of the rectangle with all contour lines leading to zero, like there: https://opengeofiction.net/#map=13/-44.9911/146.0147&layers=V If I want to add a topo layer for a new rectangle one year later, how to prevent at best the overlapping problem that it may cause on the join line of the 2 rectangles ? Is it better to keep the 1st rectangle’s OSM file, then add the 2nd rectangle’s topo curves and reimport both ?

Also, when I send to the admin, should I close all the contour lines manually on the side of the rectangle or is it done server-side ?

Best regards, SC.

Comment from Luciano on 16 September 2021 at 01:12

I would like to write a long, detailed response, but I don’t really have time right now.

Short answer: I am personally strongly committed to getting topo not just working, but working better than it ever did before. My interest and focus on topo geofiction is on of the reasons for my strong commitment in taking over hosting this project.

So eventually yes I hope to be supporting lots of topo projects, both with better documentation and better support.

Meanwhile, feel free to draw contours of edit heightmaps.

Conversion from heightmaps is not something I’ve done successfully. I do believe it could be possible, though. Heightmaps (in NASA’s SRTM format) are integral to the OpenTopoMap workflow.

Comment from SwissCrusader on 16 September 2021 at 06:38

Thanks for your answer Luciano !

Comment from mstr on 2 October 2021 at 19:16

Hi SwissCrusader, hi Luciano,

I’m also very interested in this topic, but no need to hurry!


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