UDK Ios / Lightmap issue

hoenheim

Hello Polycount !
I'm a student in computer graphics and my last job is to create a little game on UDK ios for Ipad2 with some friends.

However, we get some lighting issue when we export our work on Ipad
Everything works right in the mobile previewer and in the viewport (obviously).





But once we cooked the game and test it, we get this :



Look at these crappy shadow on the metal bar to the left ='( There are a lot of places with that kind of problem.

I heard that when you do not render your lighting in "production" quality, the engine gives your the poorest quality for your lightmap. But the lighting you can see is render in production.

So, now, I think that what the mobile previewer show me is completly false. Do I have to improve the padding of my mesh ? It is better to give it a bigger lightmap ?



Thanks for your answer.


To complete my message, Here's some screens of the work we already did for the project








Thanks for your attemption.

Eric Chadwick

This looks wonderful. I can't really tell what the shadow error is. Can you circle it, or provide a closeup? Yes, more resolution will usually help fix shadow jaggies, but you have to be careful of the download and memory costs. Sometimes though you just have to live with some crappiness when running on limited hardware.

hoenheim

Yeah, sur ! It's here :

http://uppix.net/3/e/0/83bcec8af8b72aabfe884c663eafb.html

I'm sorry, only my friends have an Ipad, so I can't make you an other screen today ='(

In fact, I don't understand what the Mobile previewer is doing with my lightmap. When I enable it, I see a little quality difference between the mobile and the PC (Does it use the PVRTC'ed version ?) and so I though that I will get that same quality on my Ipad. That difference between previewer and exported version is "normal" ?

Maybe as you said Eric, I ought to live with but it still hard to accept =(

Eric Chadwick

Hmmm. Now I see it. It could be PVRTC compression artifacts. I remember researching the format awhile back, but with a custom engine.

You could try adding some noise to the source lightmap, see if that helps reduce compression artifacts. I remember this working well with DXT, and also with Nintendo's compressed texture format.

hoenheim

The only way I found to modify my lightmaps was to add a Simple lightmap modification wich blend in Modulate mode a texture. I could try to add some noise by this way but I'm absolutly not sur that I will get the wanted result.

On Epic forum, a guy told me "make sure to export using the FrontEnd for better compression of the light maps." but we already use Frontend.