I want a transparent background in Arnold rendering.

Anonymous — Wed, 10 Apr 2019 06:29:19 GMT

How can I save the surface of those droplets as images with complete transparency?

Re: I want a transparent background in Arnold rendering.

halfstone — Sun, 05 May 2019 00:24:02 GMT

It's possible that they are, but the rest of your settings might be making it difficult to see.

It looks as though you have your IOR turned up fairly high - this can bend light to the point where the rays are not showing the transparency at all.

Also, you have a black or dark gray plain background - what are you expecting to see behind the droplets? I would recommend that as a test you put something behind there that will show unequivocally that there is or isn't transparency.

I recommend two additional things:

First, once you've put something behind the model to make sure you're seeing through, (temporarily) turn the specular weight to "0" and the transmission IOR to "1". This will guarantee that what you see is not being altered by bent light rays or overriding specular reflection.

Second, In the Attribute Editor of the surface, make certain that in the "Arnold" rollout the "Opaque" checkbox is unchecked.

My guess is that by doing these things you'll see the transparency. Once you do, you can increase the specular weight and IOR incrementally to get the effect you want.

Note that by default, the transmission IOR is set to something like "1.5", which is inappropriate for bubbles. That's the IOR for glass, which will give you a lens-like refraction. Start with "0" (no bend to the light - same as a vacuum), and make tiny changes so you can observe the result.

Do the same with the specular (reflection).

Also note that if you are rendering against an empty black background, this background is not "nothing" when it comes to reflections and refractions. The surface will reflect the background - if it's black, that will contribute to the render.

One trick is to use a SkyDome light with a spherical panoramic image mapped to it. Turn the intensity to "0" so it contributes no light, and in the Render section of the attribute editor, turn the "Primary Visiblity" to "O". This will result in it not showing up in the render as an object, but it will be visible in reflections and refractions.

Go through these steps and re-post. If that's the answer, great. If not, please include your file for more information.

topic Re: I want a transparent background in Arnold rendering. in Maya Shading, Lighting and Rendering Forum

I want a transparent background in Arnold rendering.

Re: I want a transparent background in Arnold rendering.