How do you make some parts of a material transparent?

Article Details



Poster: Morten
Article ID: 731
Posted: Fri 05 Feb 2016
Approved: Yes

QUESTION
How do you make some parts of a material transparent?

ANSWER
You will need a special Color Map texture with a mask channel in order to make parts of a Standard material transparent.

A Color Map texture normally has 3 channels: red, green and blue.

In addition to the red, green and blue channel, you can add a socalled alpha channel to the texture if you've got Adobe Photoshop, GIMP or a similar image editor.

The alpha channel can be used for 3 different purposes in Lumion:
  • Color Map Alpha masks Reflectivity (For making parts of a material more or less reflective)
  • Color Map Alpha masks Transparency (For making parts of a material more or less transparent)
  • Color Map Alpha masks Emissiveness (For making parts of a material more or less emissive)
In this article we will focus on the second option, i.e. making parts of a material transparent.

PROCEDURE

1. If you're using Adobe Photoshop, please click here to see how to add a transparency mask.

2. Once you've added the transparency mask to the Color Map texture, please click here to see how to save it as a 32-bit texture in TGA, BMP or TIFF format.

3. Then open Lumion and add a Standard material to the object in Lumion.

4. Assign your Color Map texture with the alpha channel to the Color Map slot in the Standard material.

5. Then click on the Extended Settings (down arrow) button to expand the material panel:



6. Click on the Settings tab, and finally click on the Scissors button at the bottom:



The alpha channel value is converted from 256 levels (ranging from black to white) to various levels of transparency based on what star quality you render your images/movies in:
  • 16 levels of transparency in 5-star render quality.
  • 8 levels of transparency in 4-star render quality
  • 4 levels of transparency in 3-star render quality.
TIP: Here's a longer tutorial video that shows you how to create a transparency mask in the Alpha channel of the texture in Photoshop, and saving it as a 32-bit TGA, BMP or TIFF texture:






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