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View Full Version : Is it possible to map movie with alpha channel on to plane ?



James Moore
04-09-2018, 04:23 PM
I have Action Essentials and I want to map a dirt charge, for example, on to a plane in LightWave where the alpha makes the rest of the plane transparent? Is this possible?

I've tried using a standard surface and using the movie file as a texture map in both Color and Transparency settings in the Surface editor but I can still see the plane somewhat.

lertola2
04-09-2018, 09:16 PM
Use your movie as a clip map. Any white areas in your movie will be clipped away.

MonroePoteet
04-10-2018, 08:32 AM
The downside of a Clip map is that it's either opaque or transparent, but can't be semi-transparent as can be attained using the Transparency channel. If you want to use the Transparency channel on a Standard material, make sure your Refraction Index is 1.0, and either set Specular to 0.0% or feed the Alpha channel into the Specular channel as well. Otherwise, you'll get "reflections" off the transparent portion of the surface.

For a Principled BSDF material, send the inverted Alpha channel into Transparency (using Invert Scalar node), make sure Refraction Index is 1.0 and also set Transmittance Distance to "large enough". In the case of a 1m sphere (in the sample scene), I used a Transmittance Distance of 10m.

A sample scene is attached with both Principled BSDF and Standard material spheres with an Alpha mask applied. The Alpha mask is blurred so it has a fuzzy edge, which isn't possible with a Clip map. Since the background of the AlphaTest.TGA file is black, the Principled BSDF representation seems more accurate. As well, the Standard material still casts a shadow through its tranparent portions.

141125 141126

141124

mTp

lertola2
04-10-2018, 07:15 PM
The downside of a Clip map is that it's either opaque or transparent, but can't be semi-transparent as can be attained using the Transparency channel. If you want to use the Transparency channel on a Standard material, make sure your Refraction Index is 1.0, and either set Specular to 0.0% or feed the Alpha channel into the Specular channel as well. Otherwise, you'll get "reflections" off the transparent portion of the surface.

For a Principled BSDF material, send the inverted Alpha channel into Transparency (using Invert Scalar node), make sure Refraction Index is 1.0 and also set Transmittance Distance to "large enough". In the case of a 1m sphere (in the sample scene), I used a Transmittance Distance of 10m.

A sample scene is attached with both Principled BSDF and Standard material spheres with an Alpha mask applied. The Alpha mask is blurred so it has a fuzzy edge, which isn't possible with a Clip map. Since the background of the AlphaTest.TGA file is black, the Principled BSDF representation seems more accurate. As well, the Standard material still casts a shadow through its tranparent portions.

mTp

It is hard to make things truly transparent with transparency. I spend some time trying and I could not come as close as you did. Clip maps are much better because they work in all situations and with all materials. There is an easy trick to make soft edge clip maps. Just add some noise to the clip map and make the scale of the noise much smaller than the size of a rendered pixel. Use the PShop Screen blending mode to add the noisy layer to the layer below. Antialiasing can smooth out the clipping in partially transparent areas because each pixel contains a lot of different noise values. In the attached image the top sphere has a soft edge clip map created by using the turbulence texture sized to 1 um. The amount of transparency can be adjusted by making the turbulence texture more or less visible and by adjusting the gradient layer.

-Joe

http://forums.newtek.com/attachment.php?attachmentid=141143&d=1523407327
141144

jeric_synergy
04-10-2018, 08:04 PM
Whoa!!! Jedi-level tip! Thanks Joe!

Chris S. (Fez)
04-10-2018, 09:06 PM
Whoa!!! Jedi-level tip! Thanks Joe!

Wow. Yeah.

adk
04-11-2018, 04:55 AM
Great tip ! Thanks a bunch for sharing that gem lertola2 :thumbsup:

MonroePoteet
04-11-2018, 07:22 AM
Yes, great tip! Thanks!

mTp

James Moore
04-11-2018, 04:32 PM
Thanks for the replies!

I've found that I'm getting a decent result by using a standard surface with the Action Essentials clip as a texture map in color and using it as a texture map using Alpha blending mode in Transparency with transparency at 100%. Setting the refractive index at 1.0 appears to have made my plane disappear leaving only the alpha'd clip visible.

I tried using the Action Essentials clip as a Clip map but I didn't get anywhere near a good result. I need to explore the steps lertola2 suggested in more detail.

erikals
04-12-2018, 03:39 AM
for LW2015, Dpont has a "Greenscreen" node, could be of help in certain situations.

Color Key
http://dpont.pagesperso-orange.fr/plugins/nodes/Additionnal_Nodes_2.html