Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

Lightmap calculation

I need some Informations about Lightmap calculation, hopefully someone can help me:

  1. Are Lightmaps calculated per static Object on CPU. So one Thread is used per Object?

  2. Then the Lightmaps are combined in a Atlas Texture?

  3. How does this works? Doesn't the Lightmap of one Object is dependent from Indirect Reflections of other Objects?

Product Version: UE 4.21
more ▼

asked Jan 11 '19 at 02:00 PM in Rendering

avatar image

91 3 5 17

(comments are locked)
10|2000 characters needed characters left
Viewable by all users

1 answer: sort voted first
  1. Lightmass is multithreaded but I don't think they split the task based on objects. They probably use a raytracing specific way to use resources.

  2. Yes, the more lightmaps you have the more atlases are created.

  3. "Lightmass creates lightmaps with complex light interactions like area shadowing and diffuse interreflection." (From https://docs.unrealengine.com/en-us/Engine/Rendering/LightingAndShadows/Lightmass )

more ▼

answered Jan 11 '19 at 02:19 PM

avatar image

1.6k 80 94 146

avatar image SebaSopp Jan 15 '19 at 11:25 AM

Hey Zoltan, thx for the answers... I've got more :)

Lightmaps need padding between UV-Shells. In the Lightmap Atlas it looks like they fill the padding just with black... link

Wouldn't bleed the black into a UV-Shell if we sample near the edge of the shell (interpolation...)? Or is there some kind of edge padding?

alt text

avatar image ZoltanE Jan 15 '19 at 11:42 AM

I've seen dark or light bleeding on objects where something went sideways but with reasonable UVs and lightmap resolution things should work fine.

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question