Hi Friends,

I am trying to find a good setup for the light-mapping system called dual lightmapping. Let me explain shortly what that means. This technique uses 2 lightmaps, one when you are far away including all shadows and lights. So there is no dynamic light needed. The other lightmap contains only indirect lighting. Thus it works with realtime lights and shadows when you are close to the camera. The engine blends smoothly between both lighting situations in a given distance.

Here are 2 images of some of my experiments.

The first image is very simple. You see one light and the results of lightmap, dynamic and dual map (right click on image to zoom in):



The advantage is that it works fine in a distance. The lightmap is almost exactly the same as the dual map result. Thus the blending is perfect even when I set shadow distance to only 10 meters.
The disadvantage is that it makes bright spots too bright and washes textures a bit out. And specularity is rarely visible.

Here is another approach. I use only very subtle lightmapping to get more specularity from real-time lights. So I light the lightmap only from emission textures. There is no single light that affects it:



Spec and bumps are better visible but in a distance it gets very dark when the lightmap takes over.

Actually the dualmap system has advantages when I want to animate lights and shadows. But the disadvantage is that it works not very good with normal and spec maps especially when I compare it do directional lightmapping as an alternative.

Can you give me an advise how to proceed? What setup do you prefer?

I like the lightmap + dynamic lights the most and i don't feel like it's getting too bright. The last scene looks a lot brighter than the lightmap only version though, so i'm not sure if you were aiming for the darker part or the brighter part.

The blury look actually looks more like a bloom effect and nice. For example i really like how the last pic on the 2nd example looks like, it's quite soft and has a really interesting shading.

Just my opinion.

Are those models all from your last scifi pack? I think i really need to get one of those oneday.. just to go crazy with my pro license hehe. Looks really awesome.

Yes, I made some corridors from the models of that pack. And I will add a few new models and textures. Then it will be released as a new level construction set with a sample level. Currently I am testing. I also want to make a nice video as I did for all our last packs.

why not just make the second lightmap (the distance one) a little darker so that when they mix, it wont be so bright.

either way i like the first one better. the results look much more consistant, and the extra brightness still looks good, although we might not have a fully informed opinion since i know sometimes a screenshot can look great, but in motion sometimes things can look really bad from the same scene.

Yes, you are right. In motion it does not look too convincing with a bright lightmap. The reason is that only dynamic lights affect spec and normals and the lighting from the map looks too flat. Thus I personally prefer dynamic lighting or directional lightmapping (radiosity normal mapping) like UDK, Source or Vision3d are doing.

It is really hard to tell. The pure lightmap is so great with fantastic soft shadows and ambient occlusion. But for my kind of geometry I need spec bumps to have convincing details. In a dirty industrial environment it could even work with pure lightmapping.

It looks very good and is a nice idea! I am still a big fan of lightmaps. But it looks like you got a great detail of both worlds.

What I am really looking forward to in the future is real-time radiosity. Now that would be bliss.

Yes, William. I am in touch with a few engine developers. And realtime radiosity is already in the works. Especially with DX11 and CUDA/directCompute there are a lot of options to realize this. I already saw some prototypes. The current hardware generation can handle this (Geforce 470/480).

Here is a video of a bigger map I made:

http://www.youtube.com/watch?v=a_O74nTYvcQ

This version only uses real-time lighting, there are no shadow maps.