New and old lighting techniques and their terms

Development World Creation
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Hello everyone,
I hope you are all doing well.
I was searching and learning about lighting in Unreal Engine but I feel so lost about this topic.
Because I found a bunch of resources from youtube, forums, and documents and I came across a lot of terms and techniques like

Baking, cooking
Lightmass
Lightmap
GPU/CPU Lightmass
Lumen

I searched about these terms and I generally get the concept but I can not distinguish which technique is used for what?
What techniques are no longer used with the arrival of the lumen?
Which are old and which are new?
Were you able to distinguish them?

Take care guys,
Have a good day!

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If you’re using 5, and are building for anything other than a phone, you just need Lumen.

If you are building for a phone or targeting older systems, then you need everything else in your list.

:slight_smile:

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A bit more info

Baking and cooking refer to the general process of getting the system to figure out what something’s going to look like beforehand, and then fix that, and just play it back later. It’s a term very often used in connection with light building, but also now particle systems, volumetrics and many other things.

Lightmass is the unreal static lighting system. You bake the lighting, and everything looks amazing, but you have to wait FOREVER to it to finish.

A lightmap is basically like a UV map ( UV is channel 0, lightmap is channel 1 ), except it’s used to store how the light and shadows play on an object during the light build.

Normally, the CPU is used to build light, but somebody came up with a snazzy plugin to build the lighting on your GPU. It can be a lot quicker, but does cut some corners.

Lumen is the new system which makes real time lighting look like baked lighting. It does a pretty good job.

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To be honest, this message made me feel revitalized :smiley:

Firstly, thanks for your response and precious time.

Excuse my lack of knowledge about Engine but I want to ask a couple of questions

I use UE5 to make video game environments. I mean, my levels are not for cinematic purposes.

They are for a game purpose.

My question is,

You said that we won’t be using bake for lights anymore,

Do we still need to bake 3D models?

My second question is,

Is ray tracing not used because the lumen is coming?

The reason for this second question is, that I saw a setting about hardware ray tracing supporting lumen?

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Can you be more specific about mesh baking, which process are you referring to ?

As far as I know, ray tracing is limited to RTX 2/3 000 series. The most used GPU according to Steam’s latest hardware survey is still the GTX1600 series. Gamers want pretty good, but they don’t want to pay to install a car in their PC. So ray tracing can speed up finished results, and make things look better, but it’s more of a production thing.

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Let’s say I want to add a 3D mechanical cat model to my scene.
It has 1.5 million vertices and a lot of polygons.
Can I bake it to increase gameplay performance or should I?

Thank you,

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You mean poly reduction in the source package? ( Blender, for instance ).

I’d still say a big yes to this, but you might want to canvas opinions on that.

Nanite is amazing, but if you rely on it solely, you’re basically shutting out everybody without a decent GPU. People can switch Lumen on/off in the game options, but if you just chuck a load of very fine models in a scene and hope for the best, Nanite will basically do nothing on a lot of lower end GPUs.

I guess the only way you could safely do it would be to have more than one copy of each level, or blueprints that swapped meshes depending on load etc.

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