TERRAIN_MAX_VERTEX_LEVEL Significance

[Guest Stormshadow]

I'd like to bring this issue up again and perhaps share some personal experience at creating mesh from scratch (that is, building grey level contour maps and converting to DEM!).I'm using a 1m separation in my grey maps - that is, terrain contours are separated by 1m. Tough job (actually a friend of mine is helping out with this!). Then there's the .inf file - the tricky bit. Started off with an LOD of 11 and with TERRAIN_MAX_VERTEX_LEVEL set to 19 - mesh is visible. Decent mesh but for 1m contour separation I'd expect much better results.I then tried LOD = 12 (which basically means 9.6m between elevation samples - smashing sample size). With TERRAIN_MAX_VERTEX_LEVEL = 19 mesh does not show up! Changed that to 20 and mesh becomes visible and results are extremely promising.My question is: howcome mesh appears as soon as I change this parameter to 20!? Is it because with TERRAIN_MAX_VERTEX_LEVEL set to 19 (which is the default setting), a sample size of 9.6m between elevation posts is too small to render and hence, on changing TERRAIN_MAX_VERTEX_LEVEL to 20, the sample size is somehow slightly increased for mesh to become visible?You might be asking why I'm using such a high LOD - well, the terrain I'm creating spans from 0m to 254m and using LOD =11 (~17m between elevation posts) would produce less accurate results than LOD=12 (~9m between elevation posts) in my view.Storm

[Justin Toposim 16]

HI Storm,TMVL acts as sort of lens that will bring the terrain mesh into sharper focus as the values increase. It's sort of a throttle on the terrain engine.-------Justinhttp://www.fsgenesis.netHigh Quality Scenery for FS200x

[Guest Stormshadow]

Hi Justin,TMVL sure is a throttle - frame rates drop dramatically on increasing it - first thing I noted.So the answer to the question: "Howcome at LOD = 13 with TMVL set at 19, no mesh appears" is that TMVL = 19 is not a powerful enough lens for such an LOD level?Second thing: I noticed that LOD = 11, TMVL = 21 and LOD = 13, TMVL = 21 (same terrain contour separation) produced the same results! Why then do I have to bother about the LOD value if I get equal results!CheersStorm

[Guest sgreenwood]

"Why then do I have to bother about the LOD value if I get equal results!":) Thanks, Storm. You don't! http://forums.avsim.net/dcboard.php?az=sho...g_id=1200&page=Regards, Steve

[Guest Stormshadow]

Thanks Steve...I sorted out and understood what's happening in the NW coordinates part of the inf file, but now I have to get to grips with the TMVL issue! You mentioned FS9 - I'm still playing around with FS02, but I guess, what you noticed in FS9 is the same for FS02, right?The problem is that at LOD=13 and TMVL set to 19 no mesh appears and I can't understand why. I could do with TMVL set to 19 and nothing else, since framerates drop when TMVL is set higher. It seems that at TMVL=19 the farthest I can go is LOD=11.I'll have to checdk out your site again..I believe you included some examples os how TMVL affects the scenery...Regards,Storm

[Guest sgreenwood]

Hi,"You mentioned FS9 - I'm still playing around with FS02, but I guess, what you noticed in FS9 is the same for FS02, right?"With FS2002, there is a very slight improvement with the higher LOD values, but I don't feel they are worth the limitations of LOD 12."The problem is that at LOD=13 and TMVL set to 19 no mesh appears and I can't understand why."TMVL seems to serve two functions: * setting the value to higher than 19 enables the display of higher LOD mesh, more like a switch than a "lens". I think it is required for LOD values greater than 10. You may want to recheck your LOD11 results.* it also increases the amount of detail rendered when using high resolution mesh. This is true even for 90m and 60m data with LOD values less than 10."I could do with TMVL set to 19 and nothing else, since framerates drop when TMVL is set higher."Yes, but you lose a lot of detail. Lowering your Terrain Mesh Complexity slider may be a better option. The lower setting does, however, hide flaws in mesh, so I recommend testing mesh with a settting of 21, even if you don't plan to use that value every day. Just another way to check mesh quality. I think the framerate drop is due to the higher resolution mesh data, not the TMVL setting itself. You can test this by flying in an area with low LOD default mesh. Check your average FPS with TMVL = 19, then again at 21. I doubt that you will see any difference because there is little data to be rendered. It should be the number of elevation data points/unit area that affects performance.I have a set of "pseudo-mesh' files for Maui that illustrate a number of aspects of mesh rendering. The differences between FS2002 and FS2004 are substantial. The files are different combinations of LOD and elevation, so you can easily see the ranges for which each LOD is rendered. The mesh boundaries are much clearer in FS2004, which handles the transitions more precisely, but they can be seen in FS2002. Good for testing TMVL values as well. (The readme file suggests a few things to look for, but I have already used the data to test other issues.)You can download the test data from: www.fs-traveler.com/cgi-bin/maui-lod-test.zipSince the elevation is constant for each LOD/elevation combination (LOD9 through LOD13), the bgl files are highly compressed so the zip file is only 100kb.Let me suggest one test you may find quite interesting:Load and activate my 10m LOD10 Maui mesh (free download from my site if you don't already have it). Activate only the LOD12 Maui test mesh at the same time. Then notice how small an area under the aircraft is rendered with the flat LOD12 data. Repeat the test, replacing the LOD12 test mesh with the LOD10 test mesh, and see how much further the flattened test mesh extends from the aircraft. One can compensate for this limitation of LOD12 mesh, but the result hardly justifies all the additional complications introduced.Steve

[Justin Toposim 16]

HI Storm (& Steve),To put the issue to rest once and for all, you are correct Steve that the terrain engine can not, in it's current incarnation, display LOD=12 at all. The highest LOD it can display is (LOD=11) 19.2m. This is straight from an MS FS9 developer.While LOD=12 terrain will not hurt anything if installed, aside from the extra disk space, only 19.2m will be utilized, and only if the TMVL is set to 21.This restriction will probably be removed in the next version.So, you were half-right, Steve. :-)-------Justinhttp://www.fsgenesis.netHigh Quality Scenery for FS200x

[Guest Stormshadow]

Hi agin Justin & Steve,Ok, so we agree that the terrain engine can only render at LOD 11 (sampling at 19.1m) - in fact that is what I'm experiencing.Question about contour separation - you may have, by now, guessed that I'm developing mesh the hard way since no DEM is available for the Mediterranean Islands. So I have to create grey maps and convert to DEM using Grises. I tried a contour separation of 5m and then 1m. The result using the latter is extremely promising. As I see it, what's happening is that with 1m separation resolution increases, hence the positive results. Any comments about this ?By any chance any1 knows where I can obtain the file format of DEM as I'd like to know exactly how the grey-data is converted to DEM?Steve/Justin - I zeroed the Terrain bar in the display properties and have seen no effect on the new mesh - is this normal?Cheers people,Storm