How to animate visibility of a scatter object?

[nb13ki]

Hi,

I am trying to animate the visibility of this tumor (yellow/ pink cluster).

I tried using a mix shader, but I keep getting black areas (I'm guessing it's where the object intersects with itself)

I unchecked double sided and opaque arnold properties

How can I animate the visibility without getting those black areas?

Thanks,

N

[madsd]

Not exactly sure how this looks animated but there should be a host of solutions to your problem, visually, everything from sticking the tumor on a card, prerendered and fade it out with Opacity, to disintegrate into fragments that disapear over time via particles, or simply just use some kind of opacity fade which I think your initial attempt is based on?


The black stuff is overlapping faces and should be solved in the actual animation of the tumor.
How does it animate? does it wabble and crunsh? or, its hard to say.

For quick job, just render tumor out, put on a plane as animated sequence and render final, it does not look like you have much GI going in there, so cards will be fine, in scene composit.

[nb13ki]

Thanks for your answer! What do you mean by card? Like make the tumor a bitmap for a plane and fade it? I was hoping to have it fade while the camera is moving.

[nb13ki]

I guess I could render the sequence twice, once with the tumor and once without. Then just overlay them and fade one in and out.

[madsd]

Sounds like a nice and simple solution, however, if the body has a coat, you will lose that coat if you composit.

So you could stick the plane into the body to get the surface going, if it reflects.
If you animate the camera, you can just turn the plane with the tumor on so its always facing the camera.
OFC this wont work if you spin around the tumor, but a bit of paralax then this is just fine, remember you are doing very illustrative explanatory visuals, so you arnt breaking any laws doing a card, as its pure illustrative, not photoreal.

[madsd]

you can also render a reflection AOV out of the body and disable it on the main body render, so you got 3 layers. background body, mid card with tumor, front reflection if you got any, on the body, else, sure just comp over and fade 🙂