24 January 2021

Log Cabin ReLighting – Tips & Techniques – Ian Finquelstein

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Introduction

Hi, my name is Ian Finquelstein. I’m from Mendoza, Argentina. I was studying software engineering until two years ago i decided to switch careers and begun my journey into game dev. Its been rough for my self-esteem since i was doing pretty good at university and it meant quitting all that and start from scratch, but my hope is it will pay off once I land a job at the industry i just have to stick to my gut.

About a year ago I decided to focus my study into lighting and thus began my journey into countless videos, articles, posts, forums, etc. you name it if it’s on the internet I have probably seen it. Learning is hard, but learning to learn is even harder. There is no magic recipe for that, every person is different and what works for someone may not work for you.

What works for me is I read, watch and skim through content as much as I can, in time through experience and instinct I know what information to keep and what to discard; then I start transforming all that information into knowledge by building my own notes and diagrams on the subject; finally if there is something I didn’t understand then I let all that information sleep on the back of my head. After a while (it could be days, weeks or months) I come back to it and give it another go. The key element in learning is patience.

Finally and we have all heard this: “Practice makes the master”. It doesn’t matter how much you study, if you don’t put that knowledge to work then it becomes useless information. What brings us here.

Goals of the Project

⦁ Achieve cinematic quality no matter the fps.
⦁ Set up the scene in a way that if I want to make it performance friendly I don’t sacrifice too much quality.
⦁ Try different moods or times of day from my previous projects.
⦁ Put all my knowledge into practice, learn new things and carry those lessons to the next project.

First Steps

I usually look for a scene that I like, in this case, it was the log cabin which is free in the unreal marketplace. I do this because I want to spend most of my time lighting and not building a scene that could take me months to achieve.
I remove all lighting in the scene, place a Lightmass Importance and set up a Postprocess volume without all the bells and whistles so that I can concentrate only on lighting.

PP_Settings

Note that I reduced the Film slope and I usually keep it that way because I don’t like how it affects the contrast and colors of the scene. This way I get a much more muted scene to work with and I can add contrast later if I want to.

Then I analyze the scene materials values to check for proper value ranges and lower all lightmap density for faster iteration times.

Reference

After I decided on what scene I want to work with I move on to deciding what I want the scene to look like, so it’s reference hunting time.
We should never work without visual references. Gather images of things you like, it can be: the color palette of the image, the composition, light direction, use of fog, etc. take bits and pieces of every image, they can also be things you don’t like about it, as long as it gives you an idea of what you want to achieve.

In CG we try to imitate reality but not try to replicate it because more often than not reality is quite boring So my advice is: take the reference as a starting point to base your work on reality but then enhance it with your own touch even if it’s not based on reference, sometimes realism needs a little push. (A really good video on this by Andrew Maximov: https://www.youtube.com/watch?v=BqZzxAmlKP4

Lighting the scene

At this point, I have decided what to light and how I want to light it. Now it’s time to actually do it. For this, I follow a simple workflow that I adopted from Chris Brejon in his book CG-Cinematography (https://chrisbrejon.com/cg-cinematography/) in case you haven’t read it its absolute gold.

Guidelines

– Keep it simple

For some reason people, including me for a while, think light rigs have to be complex. ON THE CONTRARY! It does not have to be complicated, especially in a PBR setup with Global Illumination (GI).

Lighting-SetUp

As you can see, the lighting is not that complicated. With only a few lights you can do so much.

– Identify the light sources

The first question that any lighting artist should ask: Where is the light coming from?
Place your lights like in the real world. Make it real, make it physical! Place the practical lights physically where they should be. Think like a Director of Photography (DP). Otherwise, it will just look weird.

– Light Globally

Since I want to do lighting for a videogame I have to treat my scene as if you can explore it so there cant be any lights floating around. And even if you are lighting for a cinematic instead of gameplay I think this rule still applies because you want to have a solid base to start with and refine on a per-shot basis.

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– Get the best of each light

Work your lights separately and be sure of what they do. Each light should have its very unique contribution. Test them ONE BY ONE!

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Wrapping up the scene

Once I’m happy with the overall look of the scene then I increase the lightmap resolution quite a bit on the assets that receive shadows and do a final bake with higher lightmass values to get spot-on results noise-free.

After the light bake is complete I then start to add all the bells and whistles to take it to the next level.

I add a tiny bit of bloom to make the highlights pop, a touch of chromatic aberration, usually all scenes require a little bit of AO to better ground objects and tie the scene together and finally, ray traced reflections only for really smooth objects which, in this case, are not many so it’s really cheap on performance.

For color grading I used photoshop and it was minor tweaks only since I try to get the job done with my lighting and YOU SHOULD TOO. More often than not people think that post-process can make up for errors in your lighting. In my case I added a little vignette in some of the shots, boost just a little the saturation and exposure and finally added just enough film grain to try and simulate the noise from a real camera.

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Challenges

My main struggle in this project was the use of the new GPU lightmass that’s already integrated since 4.26. Honestly, I think it’s very promising and has some great features that will make lighting any scene much easier BUT it currently lacks core features and gives very noisy results even with high settings that for me is a no-go with it. So for this project I had to use the GPU Lightmass from Luoshang which, of course, is not perfect but for now gets the job done.

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Conclusion

Lighting a scene is hard with many bumps on the road but with many happy accidents along the way, sometimes you can get stuck in a scene for weeks and suddenly you get it done in days. But the main takeaway is: study and practice both hard and smart, stick to a workflow that works for you and more important HAVE FUN or else what’s the point.