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The Limitations of Unreal's Baked Lighting System

Hi guys,

I have been doing some archviz stuff now for a bit and have come across some pretty noticeable issues in unreal’s baked lighting system- not just for archviz and interiors, but also for game and scene design. It seems as if the baking only parts of the map is impossible, and the entire level must be rebuilt every time you touch that Bake Lighting button. When doing an entire house or scene with multiple rooms, levels, etc. the time it takes to build the whole thing can be quite long. Add into this the edits that most achviz creators make to the baselightmass.ini file, and you have a painfully slow multiple hour build, even if you just added a chair into the level. I understand that in UDK (or UE3) the ability to only rebuild the lighting on certain objects was available, and this functionality was removed in UE4 for some reason. Sure, its important to preplan the lighting build and have everything you want in place before building, but at least for me, this just isn’t feasible. I like to modify and work with the scene to make it visually attractive, and having to rebuild the lighting every single time I want to see the final result takes hours.

I know that many of you more experienced artists and designers know this, but for someone not totally yet acclimated to Unreal, it is frustrating.

I didn’t post this thread just to whine about the system, but I would like to understand how people here get around this limitation. What is it that you do to make a coherent and beautiful scene without seeing the lighting until it’s built? For me, it’s very tough (maybe that’s my photographer speaking) but I like to see how the light falls off throughout the room, and ensure that it is both visually appealing and not awkward (shadows covering detail, highlights in unwanted places.) I have created scenes that look, to my eye, very nice, but have had to sit through perhaps three, four hour builds due to my additions of objects and tweaks of positions. I could have gotten around this by arranging everything beforehand and building the lighting once, but I just couldn’t do that.

I would love to see an addition in a later version unreal that sees to these concerns, perhaps allowing designers to cordon off one particular part of the level and only building the lighting there. I’m not familiar with how this dynamic worked in UDK, but something like it should be implemented in future versions of UE4.

These are just my observations, feel free to be critical and add :slight_smile:

NOTE: I kinda just discovered the forums on this site and have barely gotten a chance to explore. I just wanted to lay down what I was thinking, so if this post doesn’t belong in this category I can remove it.

Im not sure about UDK can build lighting on specific or selected object…
Unity3d can building lightmap on selected object still dont understand why so epic UE4 can’t have this features in it!!! becos just adding a small object in the scene we have to bake the whole level again gosh!

I posted about this same issue months ago. The answer was that I could use LightmassImportanceVolume to build the lighting in specific areas. But that’s not actually useful. It screws up the lighting and disregard any influence from outside the volume.

A way to make “region renders” would really improve the workflow. I can’t imagine how the world of offline renderers would be without it.

Yeah, for Archviz UE4 has a lot of limitations for sure. Being able to select a mesh and re-render or a region would be great!

I think the only way to get good at it would be to practice. There’s a large thread on here about making Lightmass more understandable so we can have more predictable results. I strongly recommend reading that.

https://forums.unrealengine.com/showthread.php?88952-Lets-make-Lightmass-EPIC-(and-understandable)

That doesn’t address a problem like when a client says can you move that chair or sofa 1 foot to the left. I set down very specific rules in my proposals about revisions and when they can occur but clients for the most part disregard them without fail. Then when you tell them it’s spelled out in the contract they get mad. They don’t understand when you tell them about lightmaps, render time, baking etc. nor do they care - they want what they want and they want to hear yes.

I was more so addressing this problem that CBR0M3 had

I wish I had a magical solution to help with clients changing their minds, but I don’t. :confused:

The solution is to have FU money. Have enough work so that you can lay down the law and charge for changes outside of the scope of service. I’m working towards that but it’s not easy.

Hi Everyone.
I suppose this is a good thread to put down my newb questions to you Unreal Vis pros without clogging the board as it is somewhat relevant.
First off, I recently left the archvis industry because I grew to hate it for various reasons. I also do work with a film collective and we are exploring doing a short cg animated film. I suggested that it could possibly be done in real-time CG so they want to see some sort of proof of concept and I have two weeks to deliver. So I decided to take some of my past projects from work to create a test film to show render quality. Now a little background, while I’m a newb to unreal but I was doing real-time arch vis since the late 90’s and not much has changed from purely “workflow” perspective.

1 Is there a way to visualize potential light map errors prior to rendering? People on here are saying Unreal is so amazing and great and there is no rendering yayyyy!!!, but I’ll bake it for a day and see errors on completion and I have to fix them and put it back in the oven for another 6-8 hours(I’m doing a full house on a single quad core). Is there a way to at least see what surfaces will receive zero bounces forget about splotches.

2 So are we lightmapping all entourage/props. Do I need to light map that bowl of fruit or book on the table as well?

3 Should I create my materials prior to rendering the light map? How do the materials affect the actual light map other than diffuse colors and reflection/opacity?

4 Lastly and off topic, I have been using matinee to create clips but started using the sequencer since it seems easier and can fit on the same screen as the main view. When I go to create a movie with the sequencer I get a black screen for a second and it records nothing. Could I be missing something? Do i need a blueprint code to record a sequence like with matinee and if so what code would I need or what else would I be doing wrong? Is there a sequencer tutorial even though its experimental.

Now my last boss used to price per image like most vis people but due to his reputation he was very expensive compared to average company. He would then back all of our hourly cost into the fee. He knew who was good and fast at what and who was weak at other things. And that included practically unlimited changes since the client always requested tons of them. I feel most of you are going to be selling Unreal as a rendering alternative and I think that’s dangerous as Arch vis clients expect lots of revisions and they don’t care about how you do it. I would do it like a software co or an ad agency and price it at a higher fixed project cost and back everything into that through hourly and expenses. With project management software you can project profitability. The client expects changes and you would need to know your software to guess render times with some accuracy. My company would render overnight and provide the changes 1st thing in the morning and would get redlines back before lunch, rinse, repeat. And most changes were minor and but would absolutely need a re-rendering in Unreal.

  1. You will get a lightmap error message after your first build if there are any, there is a way to visualize them too but I’ve never used it. Sometimes if you don’t get an error message and it’s still messed up you’ll need to increase the lightmap rez.
  2. Yes, lightmaps for everything.
  3. I prefer to get basic lighting then add my materials in and tweak lighting - bake the roughed in lighting add materials bake again.

Your boss is a nut job, open ended revisions on a flat fee is crazy. :eek: My contracts are broken into phases with one revision included per phase, after that it’s hourly.

Would integrating Nvidia’s VXGI on a sufficiently powerful GPU not allow you to have realtime GI of reasonable quality? It wouldn’t be quite as accurate as what UE4 comes with but it would be quite fast. You could turn up VXGI quality until it gives you one frame per second or even lower since Archviz doesn’t require high framerates.

Perhaps VXGI even allows you to bake the GI although I’m not sure about that.

That’s what I thought until I saw what he was charging ;). Our clients used us because we provided all of those crazy changes at no cost. Also most of our projects were pretty big and they expected to be paying for the final images regardless of the changes. We did have conflicts but it was more about unreasonable turnaround times then the number of changes themselves. But that’s another post. Thats also why I couldn’t use Unreal for as a day to day rendering solution. Too many small changes, but I’m really impressed with everyone’s work and visual quality thus far.

Whats this way of pre visualising lightmaps prior to rendering. That can help tremendously. Also any idea what I’m doing wrong with the sequencer. Thanks for your help RI3DVIZ and hopefully I’ll have something cool to show!

It says in the warning “enable error coloring to visualize” when you have overlapping uv’s - I don’t know where that is though. :open_mouth: I’m kinda new myself.

If you’re going to use 3DS Max you’ll have no problem getting answers to your uv questions here. I’m using Blender and have finally found a good method, so hit me up if you use
Blender.

Just so you know, mirrors and glass are a big problem because of inaccurate reflections, mirror in particular is terrible.

One more thing, the post processing volume is your friend. After your lighting is built you can adjust a lot of things without having to re-build.

This is an example of an animation movie in ue4 made by students in the city where I live.

If you go for a very stylized look maybe you could avoid lightmaps at all and go dynamic. You really don’t need the level of photorealism as you’d need for archviz!
Everything shot outside can be made with dynamic light/movable objects (no build time required). You could only bake the shots are that made inside of buildings for more accurate shadows. With a cartoony look (if it’s what you want to achieve) you probably won’t have very long light build times anyway since you probably won’t need to have high res lightmaps.
Good luck

Wow, so this post blew up!

Great ideas guys, and I think that we are generally frustrated with this huge limitation in the engine. But then again, we must remember that UE4 is primarily a game development platform, and not really specifically built with archviz in mind (to get passable results we have to literally edit the program in baselightmass.ini!) That being said it really has huge potential in the future, and adding such a feature would really help the engine on its way to becoming much more useable for multiple purposes. (Think about this UE4 devs… money to be made)

That being said, in the present state of things, we as developers, artists, architects, and designers must find ways to get around the physical limitations of the Unreal system, but also those though clients and ourselves to a certain extent. A client is never going to understand the way that lightmapping works, or how they cannot come back after the fact and ask to have a wall or chair moved a foot back. Some sort of clarity must be brought to the situation, and this is really only possible with us teaching and explaining it to them. For some in the industry this is obviously too far from the perfectly distilled, pure, archviz that they wanted to do, but for others it is plausible. Once clients gain an appreciation for what we do and begin to fully grasp what exactly their late feedback on a project really means, good things will come. If people really understood what game design and visualization was really like (and it was much more mainstream) developers wouldn’t have problems. Although it may sound a little out there, some sort of 5-6 min introductory video to these topics should be created and circulated, to push on this knowledge. Very popular UE4 videos only get ##,### views, while pewdiepie gets ##,###,### on what is created with this program, and people need to see this.

I realize that was all WAY off topic, but I just had to say it. The architectural visualization industry, as with so many others, is so under appreciated.

More on topic, what sort of system do you guys invision for the light baking process in UE? Is it some sort of way of selecting only a part of the scene, or is it just a way of re baking the new objects over the old? I personally would like to be able to drag out some sort of a box (like a lightmass importance volume) over an area and only have the new lighting built in that area.

Lots of good ideas floating around that I hope the Unreal devs have looked at…

I think your right. I’m going for a cell shaded minimalist approach. And yes a cartoony approach will be what I’m going for so I’m going to follow your advice. But I still have to finish this **** Arch Vis project.

Miss Daisy is great! Where do you live? France? :cool:

Montreal, Canada

Ahhh, that’s why all the French names. Vous Parlez Francais oui? I’m a bit rusty, I worked on Disney Paris and went to Paris a lot, I was never fluent just enough to get around.

Yea I speak French hehe! Went to Paris once! Would like to return one day.