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Help with TerraGear Needed

Postby pb321 » Sat Apr 27, 2019 2:45 pm

I've been developing some Great Lakes scenery, starting with a 1 x 1 degree area, using TerraGear and unsmoothed NLCD data. I've encountered some issues and I'm wondering if anyone can help me overcome them.
1. Lake elevation: In the area around KMCD, Lake Superior surrounds several islands. The land is significantly elevated above Lake Superior (and internal lakes), resulting in cliffs along the edges, unlike reality where there are no cliffs. There is also a significant difference between the WS2.0 lake and the "new" lake, but I assume that is the normal issue at the boundary of a newly generated tile. However, the difference is greater than I have seen when I've developed scenery in other (land) areas.
2. Holes: The holes seem to be as deep as the "new" lake is below the greater landmass and are filled with either water OR a land texture. I assume these are due to some areas with no elevation or NLCD data, but I thought NLCD covers an entire land area with data and, since the areas are filled, it would seem like NLCD data is in the spot of the hole. Unlike with my previous use of NLCD data, I got the normal DN11, DN21, etc. areas plus a DN00. I have searched for what DN00 is but have not found an answer. Looking in QGIS as I toggle DN00 on and off, I see only a few areas identified as DN00, although the feature count indicates 3691 in the tile. Any idea what these might be?
3. osm2city roads: I've placed an osm2city build, using the WS2.0 data as a base, over the newly created scenery. Most roads appear but some do not. I'm assuming that once the new scenery is in a decent state I should regenerate the osm2city data using the new scenery as a base and the roads should all appear.
4. Smoothing NLCD: If anyone has a script used to gently smooth NLCD data, or Grass setting they've used to smooth it, I would very much appreciate learning what has worked instead of re-inventing the wheel.

Any help will be very much appreciated!

Thanks to @legoboyvdlp's TerraGear tutorial, I have done things a little differently than I have before and it's made things easier, especially cropping the area to be generated. Thank you, @legoboyvdlp!
Last edited by pb321 on Sat Apr 27, 2019 4:45 pm, edited 2 times in total.
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Re: Help with TerraGear Needed

Postby legoboyvdlp » Sat Apr 27, 2019 3:55 pm

Not too certain about NLCD data, but for number 3, indeed, it will match the scenery better - and if you change POINTS_ON_LINE_DISTANCE_MAX to a lower setting (I tried 10 -- with very little framerate impact, but a much better look!) it will also help.
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Re: Help with TerraGear Needed

Postby pb321 » Sun Apr 28, 2019 1:59 am

Thanks, @legoboyvdlp! I'll give that a try once the holes are gone and the lake is at the right elevation.
I flew with the UFO over the new scenery and discovered that parts of Lake Superior are on the side of the "cliffs". It is Ocean that is seen in the holes and is what I had thought was the Lake. The Ocean is at 0 m (sea level, as it should be) and the top of the cliffs (where the landmass is) is over 100 m elevation. Does this mean that the OSM landmass I'm using is actually NOT recognized by Terragear? I may give another landmass source a try (I have used vmap0 before with success).
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Re: Help with TerraGear Needed

Postby legoboyvdlp » Sun Apr 28, 2019 8:40 am

Could you show a screenshot? I'm not too certain what is going on.

If you had no landmass you would see only ocean with "islands" of shapefiles on top of them. Landmass is the 'default' shapefile that occurs when no other shapefile covers that area.
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Re: Help with TerraGear Needed

Postby xDraconian » Sun Apr 28, 2019 5:58 pm

pb321 wrote in Sat Apr 27, 2019 2:45 pm:1. Lake elevation:

Please provide the ogr-decode command you used.

pb321 wrote in Sat Apr 27, 2019 2:45 pm:2. Holes:

Your NLCD package should have come with documentation. The codes are typically defined within this documentation. I haven't encountered DN00, but it is likely to be a void area.

pb321 wrote in Sat Apr 27, 2019 2:45 pm:4. Smoothing NLCD:

v.generalize[douglas, tolerance=24.0]

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Re: Help with TerraGear Needed  

Postby pb321 » Mon Apr 29, 2019 12:56 am

Thank you for your replies @legoboyvdlp and @xDraconian!
@legoboyvdlp confirmed what I was thinking and seeing, that the landmass was either being ignored or something was wrong with it. So I re-downloaded the osm landmass (land-polygons-split-4326) and re-selected the part needed. The file size of land_polygons.shp is 2 KB, twice the size of the file I had been using. So I set up another run with this new data. The command (TerraGUI) is ogr-decode --line-width 10 --continue-on-errors --all-threads --area-type (Freeway, Road, etc). This eliminated the cliffs and generated scenery that looks pretty decent. The holes are gone, too!
I will be setting up runs in the days ahead to smooth the data per @xDraconian's v.generalize setting and @legoboyvdlp's POINTS_ON_LINE_DISTANCE_MAX setting for osm2city. I'm anxious to see the results! Thank you both!
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