Author Topic: caustics and ground planes  (Read 5809 times)

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Offline Unyque

caustics and ground planes
« on: November 19, 2013, 10:44:08 am »

Having seen all these amazing renderings, I chose to download the 4.2.25 trial version of keyshot.

Here is my question. Upon watching the tutorial on caustics in the webinars, I find that I cannot get clear caustics. The video said to increase samples on the ground plane material under the advanced settings. There is no option for that, only refraction index.

I have worked for days trying various methods to improve them but I am getting nowhere fast. If the option to increase the samples on the plane has been eliminated or disabled in the trial release, I would like to know.

More importantly, if there is a work around I would very much like to know. I do a lot of works with free form glass and setting up caustics in Max or Maya is a very time consuming task.

Offline Chad Holton

Re: caustics and ground planes
« Reply #1 on: November 19, 2013, 12:15:37 pm »
Welcome to the forum!

Hm, not sure, would you post a link of the webinar you're referring to and the approximate time this was mentioned? I'm guessing that they may be using a different material on the ground plane (than the ground plane material).

Also, if you open the wine glass scene (in your KeyShot 4/Scenes folder), it gives a good example of caustics. Also, feel free to share a screen shot of what you have, if you can, and we'll try to help.

Offline Unyque

Re: caustics and ground planes
« Reply #2 on: November 19, 2013, 04:20:43 pm »
Ty, here is the You Tube link to keyshots own advanced tutorial, Caustics.

At 3:00 minutes in, it was explained with the ground plane material selected that there should have been a samples adjustment. He clearly points it out and I looked very carefully to see if it anything but the stock ground plane. It wasn't. Also I have been primarily working with the wine glass, since I figured that was the flagship model for caustics. 

Other than that, I used the the material ball with the inner sphere hidden and just about every clear material to test on caustics.
I used the wine glass scene setup for testing. Working with adding lights and various intensitys didn't improve much.

I gathered from the video "advanced 3: Focused Caustics", that the quality is tied to the receiving surface and the samples it is set for. Result; grainy caustics.

Since this is the unlicensed version I cannot give you renders. But it is very obvious that the caustics are not sharp but circular and overlapping, like Max before you find tune everything. 

Offline Chad Holton

Re: caustics and ground planes
« Reply #3 on: November 20, 2013, 05:44:14 am »
Okay, I see what you're referring to. That video was made with 4.1 and things changed with 4.2. I'm assuming the samples slider was no longer needed with 4.2 and the ground material.

The wine glass is just a quick example and existed before caustics was introduced. Wouldn't really call it the caustics flagship model, more of a happy accident.  :D It sounds like you may need to let it bake longer - and depending on the scene setup (materials used) and your machine muscle, it may take a bit of time.

I was thinking the Demo version has a screenshot option (hit "P")... well, if not, there's always the print screen button.  ;)

Offline richardfunnell

Re: caustics and ground planes
« Reply #4 on: November 22, 2013, 08:08:44 am »
The sample settings for the ground material are under the "Roughness" drop down, see the image attached. They had previously been under "advanced" drop down, guess this was changed recently. Hope this helps!