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[SOLVED partially] Lightbaking in Archvis Template Interior produces different/unexpected results

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  • replied
    Makigirl thanks for taking the time explaining, though the explanation was not needed on my account. I have to assume that you are still jumping to the conclusion that I never did a lightbake on any personal project before, which is neither correct nor really helpful to the topic. Also it is a bit odd, considering I have like seven years of unreal experience and even longer in classic offline rendering with vray ;-)

    So the points that you commented were well understood before, but I guess it is helpful to put them in context for anybody who may read this, not that they get the wrong idea.
    I only posted them to illustrate that I took my time to look beyond the documentation and have some in-depth knowledge about lightbaking, but still can be stumped by it. Also it was to demonstrate the problem that unofficial sources tend be outdated as it is the case, with the single-core-only theory. Also I didn't mean to propose that these were "golden values" to be replicated without understanding them, I just picked some rather high ones that are often mentioned in context with high-end arch-viz lightbakes.
    Of course we always should start with lower values performance wise and only increase them as needed and until a satisfactory lightbake is achieved. And after all each map is different, and even industry professionals sometimes struggle to get the light bake the way they want, if the level is complex enough.

    Also I have to at least slightly disagree in two points:
    The first maybe just not clearly explained by you or just a bit too generalized, so maybe you meant it differently.
    But if you write "You'll need to have as big uv islands as possible with the least cuts!" I'm hoping that you are not meaning that as "having as few uv islands as possible". At least on hardsurface objects this could lead to shadow/light bleed between faces that are seperated by a sharp edge and are one connected island in uv space, because there would not be any padding to prevent any of the unsharpness on lower lightmap resolutions from appearing along the sharp edge. This can be easily demonstrated by unwrapping a box as only one or two uv shells. On rounded or organic objects I would agree of course.

    The other thing were we are not totally on the same page is the smoothing. Of course it is blurring and can make you loose smaller details, here we agree but if you didn't care if some detail was lost and wanted to counter some noise than it could help to raise it a bit. And I'm referring here to my personal experience as well as the mentioned lightmass deep dive slides (slide 148 and before).

    As on why I want to recreate this look, for the sake of a deeper understanding what caused it to be different of course. You know though gathering practical experience and "feeling the unreal" ;-) is surely great and is exactly what I would recommend, but it is not the same as being truly knowledgeable. If something comes out different than I expect, of course I can directly turn to workarounds and quick fixes as you proposed. But this would leave me completely in the dark on why things happened differently and in consequence I would gain practice how to fix problems but not knowledge why they occurred.
    So I thought I take the time to ask on the forums instead of doing tests by myself which would take considerably longer.

    SOLUTION:
    I did some tests after all and it seems that the skylight used for the original lightbake most certainly had different settings. Raising the indirect lighting indensity to 2 and adjusting the color slightly leads to a very similar outcome. But as I said the only way we could know for sure would be if the creator of this map himself would elaborate what was changed inbetween.

    I will add this to the first post as well as a [Solved] to the topic, to spare others from reading through this thread unless they really want to.

    Besides that I still considering to post a comment on what happened in this thread before, because it is bothering me a lot.
    Last edited by ChristianAlles; 01-31-2020, 01:30 PM.

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  • replied
    NasteX Thanks I already mentioned these slides myself earlier in this thread, and worked through them before. But this thread wasn't originally about general lightbaking troubleshooting, but about finding the cause of a vastly different outcome in lightbaking on an existing sample map without any parameters changed. So it was more an academic inquiry about the why something happened in a certain situation than about how stuff is generally done. But sadly the thread went off on a tangent right from the start, maybe the question was badly asked.

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  • replied
    ChristianAlles This is probably one of the best guides for lightmass in my 5 years working with UE4 - https://www.slideshare.net/EpicGames...mass-deep-dive You will find everything you need there, though its a bit outdated since its made before the indirect lightning bounces and lightmass portals implementation. But it still gives you the most fundamental information about how lightmass works. I also suggest you to test the gpu lightmass made by Luoshuang if you have good gpu in terms of gpu memory - https://forums.unrealengine.com/deve...s-gpulightmass

    Shortly, the way of mastering the current rendering outdated technology is painfull, but once you understand what causes most of the problems you will be fine.

    Good luck.
    Last edited by NasteX; 01-30-2020, 08:48 AM.

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  • replied
    Originally posted by ChristianAlles View Post
    Makigirl :
    As for seamless lighting on modular pieces, I am totally with you it should work, especially considering that the map shows this nicely in the prebuilt lighting, but most of the time it appears it is not easily achieved even if the modules in questions are plain boxes.

    All I can say is that it's not as difficult at all!! Once you'll "feel the Unreal" /sry! / = you'll understand how it works you'll be amazed how easy lighting is!! We all have to learn from somewhere and gather information, put them to the test and learn from it! ...I agree that the documentation is not the best, good and bad information are all around... To be honest it's a free software!!! A lot of the good documentation was put together here on the forum or by people from here!!
    Try to see people's results that you like or trying to achieve and you might be lucky to read their posts and read/watch their tutorials!


    So would you concur that to achieve seamless lightbaking the following requirements need to be met:
    • High enough light map density (green or higher) and of course the same or very similar density on the pieces that should fit together
      Lightmaps are pixel textures! YOU decide what quality you want! If you have surfaces that receive a lot of lighting information /tiny shadow detail, gradients.../ and you want it realistic: you'll need to go with a high resolution!
    • unique uv for lightmap, with enough padding and ideally grid snapped uv shells, so that the shell edges align with pixel edges
      If you'll start to go with higher resolution lightmaps because of the quality, you'll realize that grid snapping is not that important! Main meshes maybe /walls/ but most of your objects won't be hard edged so ot will be impossible anyway...
      You'll need to have as big uv islands as possible with the least cuts! Exclude faces/polygons that won't be visible to have the higher resolution as possible with the least waste.
    • high quality lightmass world settings e.g. indirect lighting level scale 0.1 and quality 10 (or 0.2 and 5), bounces around 5 and if need be smoothness adjusted to remove blotches
      Level scale is in cm! So again you decide what resolution you're after! If you don't have details smaller than a cm why to go lower... If you do yes, go with 0.1 for archviz! And the rest will be pulled by this! You'll develop blotches due to lack of samples, so you'll need to go higher with quality... Always start lower to save time and maybe you won't even need a higher bake!
      I would always go with 10 bounce each... no more, no less = less could be not enough light "travel" from object to object to carry information; too many can cause weird results sometimes
      And NO!! Smoothness is blurring! If you have a high blur you'll just lose detail!! If you want realistic results go with 0.6!
    • baking with high or production
      Final render yes! Although sometimes you can get really nice results with medium! ...and also for test baking use medium and never preview! ...can be too "preview-y" and not even close to the better builds!
    • baking only on one core is suggested in the trouble shooting guide, though I can't believe this to be true, since this just won't be doable on anything but really tiny map
      No!! ...there are net rendered projects...
    Is there something essential missing on the list?

    Start somewhere! A smaller but a bit challenging scene! I'm sure you'll run into errors or looks you don't like! And THEN you can look up that specific problem! ...I'm just saying I can't think of all the essential things! I'm sure I'm missing out things! ...but your questions helped!!

    So besides that where does this leave us. We can assume one of the following I think:
    • light baking was changed somewhere since 4.24 pre-release
      I'd say so... or the scene was built in an earlier version! The lighting is VERY similar as you've seen in the tuned up pic by me, so I'd say it's just some smaller thing...
    • a different lightbaking method was used, experimental, gpu you name it
      Could be...
    • the settings shipped with the map are not the settings used with map, meaning different quality settings, higher indirect lighting intensity, etc.
      Could be but again your result (excluding the red color bleed) is almost the same as the example map!!
    • other suggestions?
    No matter what of the above, we have no way of knowing, except for tedious trial and error changing values rebaking, which may or may not lead to the desired outcome.

    I don't understand why you want to recreate this exact look... I do understand that it's frustrating that you didn't get the same by just baking the example map!! ...but you should move over and so your OWN scene!!

    And I think this is what is bugging me and some others like preston, that supposedly simple things like lightbaking especially in combination with modularity turn out to be a black box, which is especially bothering considering the time it takes to do lightbakes.

    This is why I suggest to start with something smaller that you can build a lot faster and practice and see differences with different builds/settings!
    Again: it's not so difficult! You'll see! And when you understand the way lighting works: you can move on to your big projects and succeed!!

    Also just to make it clear this is not to be meant as a rant against unreal or epic. I like to see everything that happens on the form as some kind as feedback. They do an amazing job and we can use all of this for free and we get more stuff to fool around with every 2 or 3 months. And most of the things we can do in Unreal just work as expected or at least get continuously improved until they work great. So it's just fair that there sometimes is struggle involved and epic can use the forums to get feedback on how to improve stuff.
    Hope it helps!

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  • replied
    Makigirl :
    Thanks for checking, and though the map of course could not have been created in 4.24.1 it most certainly was created in 4.24 preview or pre-preview, since the template in discussion uses features that only were made available with version 4.24 (sun sky/sky atmosphere and the template itself). Also this would match with the date, as I seem to remember the first 4.24-preview was released beginning of november.

    As for seamless lighting on modular pieces, I am totally with you it should work, especially considering that the map shows this nicely in the prebuilt lighting, but most of the time it appears it is not easily achieved even if the modules in questions are plain boxes.
    That is the main reason I opened this post, since the information on how to do this is all over the place and sometimes inconsistent or contradictory depending on how old the source is and at first I was very happy to see a level that shows us lightbaking, modular floor meshes and no use of distracting textures.

    So would you concur that to achieve seamless lightbaking the following requirements need to be met:
    • High enough light map density (green or higher) and of course the same or very similar density on the pieces that should fit together
    • unique uv for lightmap, with enough padding and ideally grid snapped uv shells, so that the shell edges align with pixel edges
    • high quality lightmass world settings e.g. indirect lighting level scale 0.1 and quality 10 (or 0.2 and 5), bounces around 5 and if need be smoothness adjusted to remove blotches
    • baking with high or production
    • baking only on one core is suggested in the trouble shooting guide, though I can't believe this to be true, since this just won't be doable on anything but really tiny map
    Is there something essential missing on the list?

    So besides that where does this leave us. We can assume one of the following I think:
    • light baking was changed somewhere since 4.24 pre-release
    • a different lightbaking method was used, experimental, gpu you name it
    • the settings shipped with the map are not the settings used with map, meaning different quality settings, higher indirect lighting intensity, etc.
    • other suggestions?
    No matter what of the above, we have no way of knowing, except for tedious trial and error changing values rebaking, which may or may not lead to the desired outcome.

    And I think this is what is bugging me and some others like preston, that supposedly simple things like lightbaking especially in combination with modularity turn out to be a black box, which is especially bothering considering the time it takes to do lightbakes.

    Also just to make it clear this is not to be meant as a rant against unreal or epic. I like to see everything that happens on the form as some kind as feedback. They do an amazing job and we can use all of this for free and we get more stuff to fool around with every 2 or 3 months. And most of the things we can do in Unreal just work as expected or at least get continuously improved until they work great. So it's just fair that there sometimes is struggle involved and epic can use the forums to get feedback on how to improve stuff.

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  • replied
    Originally posted by ChristianAlles View Post
    I hope it's not as conspiratorial as you make it sound, but I can totally relay.
    It really kills momentum if one has to struggle to get some of the basics work, even after watching and reading weeks of educational material.
    I mean concerning lightmass besides the official documentation, there is the lighting troubleshooting guide in the wiki, which I think was created by the community and epic released the lighting masterclass on youtube and of course there are the lighmass deep dive slides which are from 2016 and therefore a bit aged I guess, but they are also one of the most comprehensive sources on the topic. And of course there are tons of forum threads like "making lightmass epic" or "modular asset lighting problem"

    I know the usual workarounds are refraining from modular pieces or covering the seams with geometry, obscuring lighting difference through textures or decals or trying to fix the overall lighting quality by tweaking static lighting level scale, indirect lighting quality and smoothness and by using light portals and more light bounces. And as last resort we can use post processing to make seams less apparent.

    But even knowing all this I am still being stumped on how it is possible to do an light bake as smooth and seamless as it is shown in the archvis - interior level. All those quality related tweaks are already in the example interior level and that floor is still made out of modular pieces and apparently was baked without any seams. Not to mention the difference in brightness. And I really would like to know what the average Unreal user is missing, that we can't achieve the same lighting quality.
    Or does using luoshuangs gpu lightbaking was by any chance used and does it lead to different results than the default cpu light bake?

    So please epic spill the beans! It is really infuriating giving us a completely smooth lightbake sample scene without the means to reproduce it.
    Pretty please with sugar on top.
    First of all...
    I checked that example map: it was last modified on the 07/11/2019 so for sure it was not created for 4.24.1 as I've asked earlier...
    Sadly or not there are differences in different builds so it can cause different results... In the same engine, same settings will give you 99%+ the same results!

    Modular pieces should work fine with no seams, it's up to how the scene was built, lightmap uvs' and lightmass settings! You don't have to hide anything anymore!

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  • replied
    Yeah, I don't know whether it's a conspiracy or mixed priorities, from how it sounds according to my observations of the docs, the lack of being able to reproduce those samples easily, and massive sets of changes from version to version. I simply think there is too much scattered information, and somewhat less updating / guidance then it all calls for. And on another note, it's easy to not appreciate the level of quality that can be achieved with the intact features because it's such an onerous task completing a scene. When looking at least a few of the major changes, or new features, between 4.23 and before to 4.24 now, it's evident that the engine is becoming more versatile and refined. The new landscape editor stuff looks much easier to create from, the sun/sky model is quite a bit more accessible in the range of capacities it has (such as transitional day/night and less reliance on skylight exactitude to not cause problems), yet it's obvious in the forums that simple tasks are meeting with buggy quandaries and little help from the devs or those that are more experienced and skilled in the basics of scene setup.

    It's not my intent to criticize for the sake of criticizing, or to condescend from a vantage point of beginner aptitude. I'm merely trying to stoke the fires of initiative and see a major reprieve from getting upended in developing a scene, while pressing through a cascade of issues and required learning.

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  • replied
    I hope it's not as conspiratorial as you make it sound, but I can totally relay.
    It really kills momentum if one has to struggle to get some of the basics work, even after watching and reading weeks of educational material.
    I mean concerning lightmass besides the official documentation, there is the lighting troubleshooting guide in the wiki, which I think was created by the community and epic released the lighting masterclass on youtube and of course there are the lighmass deep dive slides which are from 2016 and therefore a bit aged I guess, but they are also one of the most comprehensive sources on the topic. And of course there are tons of forum threads like "making lightmass epic" or "modular asset lighting problem"

    I know the usual workarounds are refraining from modular pieces or covering the seams with geometry, obscuring lighting difference through textures or decals or trying to fix the overall lighting quality by tweaking static lighting level scale, indirect lighting quality and smoothness and by using light portals and more light bounces. And as last resort we can use post processing to make seams less apparent.

    But even knowing all this I am still being stumped on how it is possible to do an light bake as smooth and seamless as it is shown in the archvis - interior level. All those quality related tweaks are already in the example interior level and that floor is still made out of modular pieces and apparently was baked without any seams. Not to mention the difference in brightness. And I really would like to know what the average Unreal user is missing, that we can't achieve the same lighting quality.
    Or does using luoshuangs gpu lightbaking was by any chance used and does it lead to different results than the default cpu light bake?

    So please epic spill the beans! It is really infuriating giving us a completely smooth lightbake sample scene without the means to reproduce it.
    Pretty please with sugar on top.

    Leave a comment:


  • replied
    I was trying to do static only baked lighting with a directional and skylight, no reflection captures, and no other lights in the level. I placed 6 adjacent, square floors, the same duplicated for a ceiling, and used the starter walls to construct a basic room...with a door and two windows on one side. At medium quality, with indirect lighting bounces at 5 and skylight bounces at 2, the shadowing and light / color bleeding was bad. I think docs need updating as far as how basic features need setting up in order to produce coherent results for the settings. It's simply too difficult to try and fail numerous iterations of baking to comprehend what the problem(s) are, and how to fix them. The docs do not line up with the results enough in terms of how things are explained / defined, and much of it is for earlier versions that had bugs and other issues changed / reduced / removed, with new features added. Thus, the circular guessing game of causes and effects is a major deterrent to getting something complete and even having a draft version of a level that's presentable and workable. I mean, what happened? Is all the mysterious inner workings only revealed to the large teams that comprise game corporations / studios and other 'upper echelon' ventures?

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  • replied
    Ah those... to be honest it looks like a wrong reflection capture... there are circular ones on the wall too... :S

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  • replied
    No Problem!
    About the seams no problem they are not that obvious just a slight reddish tint, which is to be expected since there is a red sphere in the level. I attached some screenshots.
    Click image for larger version

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    Location of seam between meshes.

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    Closeup no seam and with seam.

    To answer your questions:
    Yes this was created in 4.24.1 creating new project > architecture, engingeering,... > archvis > no starter content and raytraced disabled. I will try using another version, though I'm not sure if this template is available in earlier versions.

    But as preston says the alarming thing is the huge difference in lighting. I always thought of lightbaking as a more or less deterministic process, meaning that given the same parameters the outcome of repeated lightbakes should be at best identical at least very, very similar. Of course we know that the computation with multiple cores can cause seams at least if the light troubleshooting guide is to be trusted. So it can't be 100 percent deterministic I guess.

    As for switching to force no precompute and clicking build to get rid of the light maps, this leads to the following result in the first screenshot below.
    This is understandable since directional and skylight are set to static and therefore shouldn't cast any dynamic light. Switching them to movable leads to the second screenshot. which looks a bit strange but this seems to be an issue with the sun sky positioner used in the template, which doesn't update correctly after switching to movable. after deleting the sunsky and undoing the delete it seems to have updated and looks like the last screenshot , which is what I would expect for fully dynamic directional, skylight and atmoshpere
    Click image for larger version

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    But as you say maybe a staff member can provide an answer. If not I will create a bug report concerning this issue.

    Cheers

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  • replied
    I don't see seams in the second screenshot. Can you highlight or draw an arrow pointing at the seams? I see how it's darker, and that is concerning since no settings were changed and the lighting was Production / High. Using a post process is capable of generating ambient occlusion and other lighting facets that change the result, and could be utilized to reduce or remove seams / leaks / noise / artifacts. However, I understand where you're coming from with the questions. The quality build options are basically presets, I think. Yet it's alarming how starkly different it is in terms of the scene's shadowing and lighting, appearing that it drastically altered settings, and it's uncertain which exact settings would be altered to produce the same differing results. Try waiting for a well-informed answer from the staff, or submitting a bug report. The AnswerHub is another place to post, yet it may simply auto-generate a suggestion to submit a bug report after several days of no replies. Trying it in an earlier UE version might yield results that are more or entirely consistent between build quality levels.

    What happens when the lighting is changed to dynamic? I think it requires "Force No Precomputed Lighting" to be enabled in World or Project Settings, and then change the lights and all meshes to movable.

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  • replied
    ...sry I didn't and still don't see the leaks in your render... BUT I know that's not the question!

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  • replied
    Was it created in 4.24(1)? ..there can be (and sadly usually are) differences in light builds in different versions...

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  • replied
    Hi,
    yes thanks for confirming that I understood you right. And of course I know that I could match the two version easily creating and using a LUT, but as I said it doesn't answer the question. Also using postprocessing won't get rid of the seams that rebuilding the lighting introduces. So it would be really interesting to know how the original lightbake without any apparent seams was created?
    But maybe it is related to my machine and something might be off, though I use a freshly installed UE4.24.1 without any tweaks/changes but you never no maybe some experimental feature was used when creating the template.
    Cheers

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