Author Topic: Noob question about HDR and lightmaps  (Read 1784 times)

Dje

    Reputation: 7
Noob question about HDR and lightmaps
« on: April 22, 2011, 01:17:42 am »
April 22, 2011, 01:17:42 am
Hello,

I'm sorry for these Noob question!

Lightmap:
-how is it working in lumion? I mean, how do i setup a light map in lumion?
-what's the effect of a Lightmap? I don't really understand what is the use of lightmap in fact :/ Is it like adding bump texture (greyscale)?

HDR:
-I saw that lumion support HDR, does it means that i can import a Dosh HDR file into lumion?
-how does it work?

Thanks for your help...
Djé

Frank

    Reputation: 29
Re: Noob question about HDR and lightmaps
« Reply #1 on: April 25, 2011, 11:32:18 pm »
April 25, 2011, 11:32:18 pm
Hello,

I'm sorry for these Noob question!

Lightmap:
-how is it working in lumion? I mean, how do i setup a light map in lumion?


You can use a lightmap in lumion by assigning the lightmap-material to an object. The influence of the lightmap is adjustable by the sliders in the lightmap-material. But you have to create the lightmap before in a rendering/texturing software like 3dsmax.

-what's the effect of a Lightmap? I don't really understand what is the use of lightmap in fact :/ Is it like adding bump texture (greyscale)?


Lightmaps are precomputed textures storing informations where an object is lighted or shadowed. You can imagine it as a wallpaper with light-shadow values wrapped around an object. Shadowed areas are black or grey and bright areas are white in the lightmap. These colors (black and white) will be multiplicated with the diffuse texture of the object. So the bright areas will become brighter and the shadowed areas darker.
Diffuse-texture is normally mapped on mapping channel 1. Lightmap is on a different mapping-channel, mostly 2 or 3. Don´t know which rendering/texturing software you use. But in the manual of it you may find a tutorial how to create lightmaps, if its implemented.

In a nutshell: Lightmaps are the pre-rendered illumination of a scene.
Deeper general informations here: http://en.wikipedia.org/wiki/Lightmap

If you use 3dsmax, for lumion you have to create a standard material with diffuse-texture on mapping-channel 1.
Then bake the lightmap with render-to-texture (shortcut "0"), using mapping-channel 2 and output into source-material by choosing self-illumination as target-mapslot.
Hope this helped.

HDR:
-I saw that lumion support HDR, does it means that i can import a Dosh HDR file into lumion?
-how does it work?

Thanks for your help...
Djé


AFAIK its not possible to import your own HDRs for lighting/refelctions.

Dje

    Reputation: 7
Re: Noob question about HDR and lightmaps
« Reply #2 on: April 25, 2011, 11:54:56 pm »
April 25, 2011, 11:54:56 pm
Thanks for your very complete response Frank!

I'm using sketchup so i suppose that i'll not be able to set some lightmaps for my model...

Djé