While not as simple as some applications, it is possible to make good use of our materials in Lumion.
Why isn’t it simple?
For a Specular PBR material to work correctly you need, in general, a minimum of 4 textures. Color, Reflection, Gloss and Normal. (Displacement is often a nice bonus, but not always essential.)
Now, If we take a look at the Lumion material interface, we can see there are only 3 texture inputs.
These are Color, Normal and Displacement. There is nowhere, at least directly, to input the Reflection and Gloss maps which, when used together, control how the light interacts with a surface.
There are some Gloss and Reflectivity sliders that can help you adjust the overall reflectivity over the whole surface, which may be enough for some materials, like a really flat wooden floor for example. But for most materials, you’ll want to make use of the Reflection and Gloss maps to get the best result.
Using Poliigon Materials in Lumion
Lumion does in fact allow for the reflection and gloss maps to be used, by hiding them in the alpha channel of one of the other textures.
Textures are made up of 4 channels Red, Green, Blue and Alpha… or RGBA for short. The color of a texture is decided by the RGB part, leaving the alpha channel free in most cases. It’s this free channel that Lumion allows us to store the data for the reflection and gloss maps.
Basically, the color textures alpha channel will be used for reflection and the normal maps alpha channel will be used for gloss.
To make use of this you’ll need to create some custom textures specifically for use in Lumion, using a 3rd party app such as Gimp or Photoshop. In this document, we’ll use Gimp, as it’s free and available to all. For our material, I’ll be using Wood Flooring 044.
Step 1: Import WoodFlooring044 Color Texture (COL) into Gimp.
Step 2: Go to the menu option Colors -> Components -> Decompose. When a dialog box appears just hit ok, the standard settings will be fine.
Step 3: In the new image that has been created you’ll now see three greyscale layers named Red, Green and Blue. Drag in the WoodFlooring044 Reflection Map as a 4th layer and drag it to the bottom layer. Rename it ‘alpha’.
Step 4: Now go to the menu option Colors -> Components -> Compose. Select RGBA mode and be sure to select our new alpha layer as the alpha channel.
Step 5: Save images as a recognizable Lumion file… such as WoodFlooring044_LUMION_Color. The preview of the new texture will look a little strange in Gimp but Lumion will read it perfectly.
Step 6: Repeat the above steps, this time loading up WoodFloor004 Normal Texture (NRM) and using the Gloss map as the alpha channel. Save the composed result as WoodFlooring044_LUMION_Normal.
Step 7: Inside Lumion, create new material and load in the Color and Normal maps that we just created, the reflection and gloss data required for our materials to look their best will be present and that’s it. Please note though that this process will be need to done for each new material you download.