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FSX:SE Getting low LODs to show up

Discussion in 'FSX terrain' started by Misho, 5 Dec 2017.

  1. Misho

    Misho

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    Hi, all!

    For photo-realistic ground textures (aerial imagery), is it possible to have low LODs to stay "on" (visible) if there aren't any higher LODs?

    For example, I have an image that, due to its resolution, produces only first 5 LODs (LODs 0-5). They are visible from afar, but disappear when user approaches them. Is it possible to force them to display at this coarse resolution?

    I know I can force the higher LOD creation which will over-sample my source imagery, but I don't want that, due to the size of resulting file this can create.
     
  2. rhumbaflappy

    rhumbaflappy Moderator Staff Member Resource contributor

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    Hi Misho.

    Some FS9 bgls will still run in FSX. It might be possible to use FS9 vector-photoreal tiles, if you remember how to display photoreal as vectors in FS9. Just a guess...
     
    Misho likes this.
  3. GaryGB

    GaryGB

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    How about using INF LOD parameters to limit low LODs to aerial imagery, and high LODs to transparent photo-real, with a 1-color image that has a single pixel of (RGB 1,1,1) color at the NW corner, then eliminate the "1-color" image via the NullValue parameter ? :idea:

    GaryGB
     
  4. Misho

    Misho

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    Oh wow - it has been a LOOONG time since I designed for FS9... I'd have to refresh my memory. Do they behave differently regarding the display/visibility limits?
     
  5. Misho

    Misho

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    I'm not sure if I follow, Edit: Ah, I do! Yo want to "fool" FSX into thinking there is a higher LOD on top, which would be transparent, so that lower LOD under it would show! I LIKE it! I'll give that a whirl :D Thanks!


    Here is my (very unique o_O) problem: I am building a spaceflight simulator (www.terrabuilder.com). I'd like to create a global cloud map. I thought about going about it from a few different angles:

    • Creating an 3D AI object that is basically a "shell", to represent clouds. Basically, 4-sided polygons tiled under the user spacecraft. After putting a quick test project together, I confirmed what I feared before - any 3D object has an absolute visibility limit of 30 nm (55 km)... although, I CAN confirm that you're able to build absolutely huge objects - my test case was a sphere with a 55 km radius (Yup- you could make a Death Star but it would be invisible until you got almost right next to it ;))

    • Creating a globe-wide photo-real cloud layer with a blend alpha layer. Technically feasible, and this is where I am at now.
    The problem is, my globe-wide cloud texture (from NASA's BlueMarble) is 43200x21600 pixels in size. This translates to about LOD5 (using Auto for LOD directive) and this is perfectly fine, viewed from the orbital heights, the clouds look beautiful. However, on the ground under the spacecraft, FSX insists loading higher LODs (7,8,9) and since the scenery only has up to LOD5, I get a "hole" right under the spacecraft... No problem, I can force upsampling by specifying higher LOD levels, but that starts adding A LOT to the file size (going from LOD5 to LOD11 is about a thousand-fold increase in file size). Also, it doesn't make clouds look any better, because they are just upsampled from the original source.

    So - I need the LOD5 forcing itself to show in place of missing higher LODs. I was hoping there would be a switch or a directive somewhere that would help me do just that...
     
    Last edited: 7 Dec 2017
  6. GaryGB

    GaryGB

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    Hi Misho:

    I must properly re-direct all thanks for any personal knowledge I may now have on this subject to Christian Stock, Richard Ludowise, and Scott Smart et al for their early research on the available land class types, which subsequently led to the wider knowledge by the FS community, of transparent custom "photo-real" land class.


    BTW: Dick has a worked example on his download site:

    https://onedrive.live.com/?id=F3950C5BBD2BCFA1!395&cid=F3950C5BBD2BCFA1


    Although the images need to be restored to some old posts, Dick also had posted some interesting info on transparent custom "photo-real" land class here at FSDeveloper.com forums.

    https://www.google.com/search?source=hp&ei=ErcpWp6sI-O6gge_8LPABw&q=http://www.fsdeveloper.com+transparent+photoreal&oq=http://www.fsdeveloper.com+transparent+photoreal&gs_l=psy-ab.3..33i160k1l2.1197.9499.0.13194.23.21.0.0.0.0.372.3374.1j9j3j3.16.0....0...1c.1j2.64.psy-ab..7.15.3000...0i13k1j0i22i10i30k1j0i13i30k1j33i21k1.0.TcXxUcSnFh4


    Regarding legacy format scenery, if certain SCASM 3D objects could (still ?) be used in FSX / P3D, IIUC, the Area( 'type B' code apparently allowed up to a 256 KM display distance, and RefPoint( V1 / V2 parameters could further adjust object visibility range.

    http://www.scasm.de/doc/sca_cmd1.htm#area

    [EDITED]

    I have not studied how FSX and P3D implemented "3D volumetric" clouds compared to the methods for FS2Kx legacy clouds which were, IIRC, rotating flat double-sided sprites, but I should think that as clouds, they also could be controlled via the weather sub-system with an even greater display distance. :scratchch

    [END_EDIT]


    PS: I have been watching with great interest, your development of space flight capabilities within MSFS / P3D. ;)

    I continue to look forward to seeing what you are able to innovate next for this project ! :)


    GaryGB
     
    Last edited: 8 Dec 2017
  7. Misho

    Misho

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    Thanks Gary! I'm trying to figure out what can and can't be used, and what are my options, but at the end, it all comes down to the visibility limit. You're mentioning 256km display distance - that is nowhere near what I need (basically, unlimited), because the orbit can reach out to thousands of km in height, and the last thing I want is the clouds suddenly disappearing from the whole globe :eek:. Likewise, volumetric clouds won't do me any good. At those heights, the clouds look flat, and I'd be more than happy with a flat 2D polygon that supports:

    1. Unlimited visibility
    2. Ability to be placed above ground (which photoreal scenery does not)
    3. Alpha channel
    4. Bump mapping (that would be amazing)
    PhotoReal can do 1 and 3... LOD0 will be visible from the extreme limit of FSX altitude (30,000 km), however, as my problem stated, as I get closer, higher LODs kick in, and doing the entire global cloudmaps with anything higher than LOD5, and we're getting into some serious Gigabytes of storage space.


    Thanks Gary! I'm having loads of fun with this, and I have made some strides since I've published the demo, but there is a lot more work to be done. Right now I'm working on animated 3D effects and ground stacking and, (eventually) the launch. Also soon, I'm hoping to have a high-fidelity EVA model of an astronaut with full skinned animation moving around in zero G.