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Lets make Lightmass EPIC (and understandable)

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  • started a topic Lets make Lightmass EPIC (and understandable)

    Lets make Lightmass EPIC (and understandable)

    I am overwhelmed by the response from Lightmass developer himself - @DanielW. I want to ask like million things right now, but certainly that's not possible. So I quickly created this Unreal project to ask for the solution to some of the basic/fundamental problem I (we all) are encountering during self learning of Lightmass.

    In Vray or Corona we can visualize/see the actual samples taken into consideration for final calculation, which in turn gives us a chance to increase samples, size or filtering to remove blotches and noise from the GI. Also it is well documented how Light cache and Irradiance Map is working in Vray and we get individual settings for subdivisions and sample number/size (We have precise control over what is going on under the hood).

    Unreal Engine's lightmass is amazing when it comes to ease of use and speed, but critically lacks when it comes to provide precise control over GI calculations and that too with vague explanations without any proper example.

    It would be amazing if we bring some the Values/settings in UI of Engine dealing with - Photons (Direct, Indirect and Irradiance). We need documentation about how the Photon mapping is working inside the Lightmass, covering all the relevant values which are necessary to produce clean GI with clear-cut contact shadows. There are too many values to understand from SceneExport.h and that too without backing of proper visual examples(It's kind of impossible to understand these values without visual examples in engine)

    Why we Architecture Visualization artist going for .1 or .2 values in Static Lighting Level scale? - To grasp all the intricate details in every corner of the space without loosing any contact shadows (Wide open diffused white walls are always difficult to deal). All Unreal Engine Architecture work is in direct competition with Vray and Corona, giving ultimate control for GI will certainly level the ground for all.

    I believe all the settings are there to produce stunning results from Lightmass (Many artists have already proved it). But unfortunately that involves tweaking in BaseLightmass.ini, which make things somewhat hazy and unpredictable (Don't know what values are doing exactly).

    Here are the Visual Example of the problems faced by almost everybody during lightmass calculation. I tried few different combinations of lighting. Whole scene is being uploaded for sharing, will give the link ASAP.

    Level one is only lit by Skylight with HDRI


    These are the Lightmass settings -




    Results











    All walls with Floor and Roof have 1024 Resolution. As you can see the quality is unacceptable, lots of blotches in dark areas. Areas coming in direct contact with skylight are well lit without bugs, all the problem is in dark areas where direct skylight is not hitting.



    In second level I have put the stationary spot lights in corner to remove the splotches (hoping for the best). Lightmass world settings are same as above.












    Using Spotlights with .1 value in Static Lighting Level scale almost always gives this infamous Light Leaks without improving the secne as much, rendering scene unusable. With 3 folds increase in rendering time.

    Long build times are not so much of a problem if in the end we know what we are going to get (Predictable results).

    Whole scene images -





    @DaneilW -

    Kindly Let us know -

    1. How to remove the splotches in the area where there is no skylight hitting directly (Areas far from windows). As you can see in the above images there are so many splotches in gallery, despite having Indirect Lighting quality to = 10 and static Lighting Level scale = .1

    2. Shadows become somewhat messy after a certain distance. How to make area shadows more clear and smooth.

    3. Whenever we put spotlights to remove dark areas, it almost always gives the annoying problem of light leaks. Clearly evident in the above images.

    4. What are Direct Photons, Indirect Photons and Irradiance Photons in relation with Lightmass and there respective uses in GI solver.


    Regards

    Unreal Engine Architectural Visualization Community
    Attached Files

  • replied
    Originally posted by Marlo View Post
    Can anybody help me what is the problem with my scene? I try a lot of things which in the topic too, but none of them solve my problem. Thanks for the help!
    I have the same problem.

    Leave a comment:


  • replied
    Originally posted by Norman3D View Post

    This is what is happening, it's bug that isn't fixed yet:



    I still get that error on 4.19.2

    I guess it has yet to be fixed...

    Leave a comment:


  • replied
    Thanks for helping the community. Cheers.

    Leave a comment:


  • replied
    Originally posted by Crawlewis View Post

    Hello guys, anybody have this file yet?
    Click image for larger version  Name:	Onlyskylight3.jpg Views:	2 Size:	313.1 KB ID:	1115451


    GoogleDrive
    https://docs.google.com/uc?id=0B3wYK...xport=download

    Dropbox
    https://www.dropbox.com/s/0ljra2l3h0...dNaji.zip?dl=0

    Microsoft OneDrive
    https://1drv.ms/u/s!Ar7INFDcXdscgnWMCXW4AKFmf0Sa

    Mediafire
    http://www.mediafire.com/download/9x...arshidNaji.zip

    4shared
    http://www.4shared.com/zip/8ARByBcice/FarshidNaji.html

    Uptobox
    http://uptobox.com/s6m3icy2uknu

    Leave a comment:


  • replied
    Originally posted by
    Unreal Engine Project (4.15) for the above test scene - [URL="https://www.dropbox.com/s/lbug8pufwo4a0ju/Lightmass_test.7z?dl=0"
    Dropbox Link[/URL].

    Will be doing some more tests soon with complex projects.
    Hello guys, anybody have this file yet?

    Leave a comment:


  • replied
    Test VLM + fog
    Attached Files

    Leave a comment:


  • replied
    Test VLM + Sky Lighting Bounces
    Use only emmisive textures (50 bounces)
    VLM(5;30) + Volume fog
    Spheres - moves objects
    Attached Files

    Leave a comment:


  • replied
    Have you tried to give the light source a "source radius" larger than zero? - This looks pretty bad. Should be better. There is also a pretty visible aliasing on the geometry. I wonder if it is your video card or your general settings.

    Leave a comment:


  • replied
    **SOLVED: I found out my mesh receiving the shadow was scaled and thus causing the bad shadows. Hope this is helpful to anyone else who makes that mistake.


    Hi All,

    I posted this in answer hub but thought I would try my luck here as well.

    I've been diving deeper into baked lighting and I'm seeing very low quality shadows produced by static lights. I've searched the forums far and wide, I've tried all the usual tweaks to remedy them but I'm running out of ideas. My settings seem like they should produce higher quality shadows so I'm wondering if I'm missing something obvious or if it's a bug.

    I made a simple test level using starter and built-in engine content. I'm using 4.18.3, forward renderer on a Mac. Building at higher quality seems to have no effect on the shadow quality. Lightmap compression is off. All the meshes seem to have enough lightmap resolution. Raising it only increases the quality marginally. Raising it too high (to 2048 for the floor) seems to break the light map (it just turns into a smudgy mess).

    Hopefully someone may have some ideas for anyone having the same issue as me.

    Here are my lightmass settings...
    Click image for larger version  Name:	Screen-Shot-2018-02-19-at-2.56.21-PM.jpg Views:	1 Size:	54.0 KB ID:	1431256

    Stationary light lightmap resolution and baked result...
    Click image for larger version  Name:	Screen-Shot-2018-02-19-at-2.20.31-PM.jpg Views:	1 Size:	101.4 KB ID:	1431258
    Click image for larger version  Name:	Screen-Shot-2018-02-19-at-2.20.39-PM.jpg Views:	1 Size:	42.6 KB ID:	1431257

    Spotlight lightmap resolution and baked result...
    Click image for larger version  Name:	Screen-Shot-2018-02-19-at-2.50.10-PM.jpg Views:	1 Size:	83.9 KB ID:	1431259
    Click image for larger version  Name:	Screen-Shot-2018-02-19-at-2.49.53-PM.jpg Views:	1 Size:	57.6 KB ID:	1431260
    Last edited by thejturner; 02-19-2018, 05:45 PM.

    Leave a comment:


  • replied
    Originally posted by Daciansolgen View Post
    I have a big problem. When I follow all tutorials on how to achieve photorealistic architecture in unreal I don’t get it. It can’t get the soft lightning and shadows. If I have sun light pointing trough the window I got light casting on wall but not reflecting the whole room as it does in real time. Can you help to achieve photo realism.
    Post a screen shot. No one can tell what issues you are facing from a simple description.

    Leave a comment:


  • replied
    I have a big problem. When I follow all tutorials on how to achieve photorealistic architecture in unreal I don’t get it. It can’t get the soft lightning and shadows. If I have sun light pointing trough the window I got light casting on wall but not reflecting the whole room as it does in real time. Can you help to achieve photo realism.

    Leave a comment:


  • replied
    Originally posted by Marlo View Post
    Can anybody help me what is the problem with my scene? I try a lot of things which in the topic too, but none of them solve my problem. Thanks for the help!
    This is what is happening, it's bug that isn't fixed yet:

    Originally posted by DanielW View Post
    The black shadow in corners is due to too much biasing by Lightmass when tracing gather rays. With point and spot lights, only the first bounce uses a gather and is affected by this bug, while the rest of the bounces come from photon mapping which is not affected. With multibounce skylight, all bounces are gathers and are affected by this bug so the artifact is much more noticeable.

    This is completely solvable but I just ran out of time for 4.18. It's high on my priority list.

    ​​​​​​​

    Leave a comment:


  • replied
    I think the main geometry neither perfect. This is an Archicad model with a fast uvw mapping... The main goal was that I would like to test it, how things going, but I guess, it's better to remodel it in 3ds max, and make proper unwrapping, with a good texel density. Anyway thanks for the tips again I'll definitely take your advice!

    Leave a comment:


  • replied
    Well done to have a bake like this after 2 days!!
    ...I think your walls are face snapped which is not ideal... you'll get those dark corners + blocky artifacts... you can try just setting a higher resolution lightmap and those dark outlines should shrink/disappear...
    I snap my walls at the corners so no overlapping faces...

    Leave a comment:

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