Author Topic: Is it possible to get ground reflections independent of shadows?  (Read 2298 times)

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Offline Ravenswood Design

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Is it possible to get ground reflections independent of shadows?
« on: February 28, 2017, 11:34:50 pm »
Hey Keyshot Forum,
 
I'm an Industrial Designer in Australia, and I use Keyshot most days of the week. I've been fighting this question for months though, and I can't come up with a solution that isn't horrendously complicated, like mirroring geometry below the ground, creating a semi-translucent ground plane and editing it out in Photoshop with clown passes and blur effects.

The thing I'm trying to do is maintain a full reflection in the ground plane without having the reflection itself occluded by the shadows cast from the object onto the ground plane. I've found that the reflections show up well in Keyshot, but once rendered out, anything that doesn't sit on top of a shadow is clipped. I've attached two different renders below. Render 1 is with ground shadows, showing the reflection without transparency, then Render 1 Transparent one shows with clipping constrained to shadows. Please excuse the cube, everything else I have lying around is client work, and not for sharing yet.

Any thoughts, or experience to share with getting this to work? What I'd love to have as an end product is a PNG render like this:
without the background, and only a semi-transparent reflection below the object.

Cheers in advance!
Nic
Lead Designer, Ravenswood Design

Offline Will Gibbons

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Re: Is it possible to get ground reflections independent of shadows?
« Reply #1 on: March 03, 2017, 11:21:33 am »
Hi. In the image you're referencing, I believe Doug used multiple passes and combined them in post. You can 'fake' ground shadows using Occlusion. See this post here: https://www.keyshot.com/2016/occlusion-works-keyshot/?_ga=1.53910314.323484694.1485464482

Between outputting an occlusion pass, using a physical ground plane (which behaves as a real material would with reflections and shadows), using render layers (if you'd like) and the clown pass, it's not too hard to do.

To get them directly out of KeyShot in one pass though... its much more difficult. My recommendation to you would be to create ground shadows as a separate pass and composite in photoshop.

Let me know if that helps.

Offline Ravenswood Design

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Re: Is it possible to get ground reflections independent of shadows?
« Reply #2 on: March 08, 2017, 05:31:58 pm »
Hi. In the image you're referencing, I believe Doug used multiple passes and combined them in post. You can 'fake' ground shadows using Occlusion. See this post here: https://www.keyshot.com/2016/occlusion-works-keyshot/?_ga=1.53910314.323484694.1485464482

Between outputting an occlusion pass, using a physical ground plane (which behaves as a real material would with reflections and shadows), using render layers (if you'd like) and the clown pass, it's not too hard to do.

To get them directly out of KeyShot in one pass though... its much more difficult. My recommendation to you would be to create ground shadows as a separate pass and composite in photoshop.

Let me know if that helps.

Cheers Will,

I think you're right in that I'm asking a bit much of Keyshot in one go. Looks like it might have to be a compositing jobby. That might be a solution for next time, since in the meantime I've hacked together an alternative solution. I'll revisit this with results once I get around to it.

Shame that there's not a clear-cut no-post-processing solution though, I'd love to be able to get those renders straight out of Keyshot, but this is the first thing I've found in 4 years of using it that I haven't been able to do. Not bad at all.