Diffusely Convolved Cube Map

Introduction

A diffusely convolved cube map is simply a blurred-down version of a regular cube map. When a shader adds the cube map to the model's diffuse map the result is similar to global-illumination, except it is extremely efficient performance-wise.

tmp.320.whatif_nmech_env-alone.jpg

tmp.320.whatif_nmech_env+lgt.jpg

tmp.320.whatif_nmech_env-none.jpg

The convolved cube map on a normalmapped model. Actual size
image byEric Chadwick,Whatif Productions LLC

Convolved cube map plus lighting. Actual size
image byEric Chadwick,Whatif Productions LLC

Lighting without the convolved cube. Actual size
image byEric Chadwick,Whatif Productions LLC

AMD Cubemapgen

Cubemapgen is great for filtering down cube maps. Sébastien Lagarde made a physically based rendering mod.

tmp.640.Cubemapgen_Tips.jpg

Some tips for filtering cubemaps in Cubemapgen. Actual size
image byEric Chadwick

Cubemapgen Cube Faces

INPUT

Cubemapgen

3ds Max

Maya

CryENGINE 3

Unity

Unreal Engine 3

+X

_RT

Left -X

+X

-X

_LF

Right +X

-X

+Y

_UP

Top +Y

+Y

-Y

_DN

Bottom -Y

-Y

+Z

_BK

Front (+Z)

+Z

-Z

_FR

Back (-Z)

-Z

OUTPUT

Cubemapgen

3ds Max

Maya

CryENGINE 3

Unity

Unreal Engine 3

c00

Left -X (180°)

c01

Right +X (180°)

c02

Top +Y

c03

Bottom -Y

c04

Back -Z (180°)

c05

Front +Z (180°)

Cubemapgen Custom Meshes

You can load your own geometry in Cubemapgen using the Load Object button, really helps to see what settings are working well.

You can also load a bitmap for the model using the Load Basemap button. There's a bug right now that causes your Basemap to be mirrored vertically... to fix it pre-flip the bitmap yourself before loading it in Cubemapgen. An Ambient Occlusion Map map makes a great Basemap, or you can use your DiffuseMap.

tmp.320.cubemapgen_nmech_cube.jpg

tmp.320.cubemapgen_nmech_basemap+cube.jpg

tmp.320.cubemapgen_nmech_basemap.jpg

Custom geometry in Cubemapgen. Actual size
image byEric Chadwick

Basemap is modulated (multiplied) with the cube map. Actual size
image byEric Chadwick

Ambient Occlusion makes a good Basemap. Actual size
image byEric Chadwick

Editing Cubemaps in Photoshop

If your cube map is in DDS cube format, you'll need the NVIDIA DDS plugin to load and save in Photoshop.

Unfortunately NVIDIA introduced some bugs when they updated the plugin, so now DDS cubes don't load mips properly. If you need to load cube maps with mips, here's an old version that does it right.


CategoryTexturing CategoryTextureTypes CategoryEnvironmentMap

DiffuselyConvolvedCubeMap (last edited 2014-02-18 16:04:39 by EricChadwick)