Applying and Creating Materials - Mastering Lumion 3D - page 93

Clipping a surface with an alpha channel
Lumion can use an alpha channel to create some interesting tweaks, and in this case,
we can clip a surface. In the previous topic, we saw that the black area blocks the
reflection and the white area shows the reflections. The same principle is applied,
but in this case, the black area removes the geometry and the white area leaves the
geometry visible.
However, you may wonder: why is this practical? Let's have a look at the
following screenshot:
In the previous screenshot, we can see a ventilation grid, and in this case, we have
simply applied a grid texture. However, along with this grid texture, we have also
saved an alpha channel. In this alpha channel, the metal grid is filled with the white
color and the holes are filled with the black color.
When the texture is loaded in the Standard material, we need to pick the
Relection / Clip / Bright slider, which by default is set to 0 . Then, we have to use
a value between 0.5 and 0.9, and Lumion will read the alpha channel in the texture
and use that information to remove the geometry. With an alpha channel, we can,
in seconds, create the illusion of a very complex geometry. This technique saves
time in the 3D modeling process, allowing you to spend more time focusing on
other sections of the project.