# caustics for idiots **URL:** \ **Category:** Off-topic\ **Created:** [May 27, 2014, 5:02pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961 "2014-05-27T17:02:14Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Nicinus](https://avatars.discourse-cdn.com/v4/letter/n/5e9695/32.png) [@Nicinus](https://forums.chaos.com/u/Nicinus)\ **Post date:** [November 22, 2014, 7:02pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/21 "2014-11-22T19:02:46Z")
What a stunning image. Couldn’t believe it was all 3D until I found it on Evermotion. ---
**Author:** ![Morbid\_Angel](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/morbid_angel/32/21272_2.png) [@Morbid\_Angel](https://forums.chaos.com/u/Morbid_Angel)\ **Post date:** [November 24, 2014, 6:52pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/22 "2014-11-24T18:52:30Z")
I wish vray had a better caustic method ☹ I’ve recently completed a project with underwater caustics. It was tough to set it up for every shot. Since the water was covering a large area, moving the directional light around for a big coverage proved difficult and also I had objects traveling for large areas so having crisp caustics was tough, I had to have the photon count super high, like 50,000 😄 It all comes down to - use pin light source like spot light or dir light as oppose to area light - it will produce soft caustics. Use low threshold the lower the search distance the more precise the caustic will look, but you will need to increase your photon count a lot for it to look good. If you see in picture below this is with very low caustic search distance, and photon count of 5000 still noisy, so I would raise that to 10000 and it will probably be fine. 2014 max scene attached. ![caustics.JPG](https://europe1.discourse-cdn.com/chaosprd/original/3X/f/6/f64ea6a1f152260c6310c705ad7911a54a2c5793.jpeg) [caustics.zip](https://forums.chaos.com/uploads/short-url/fVVe3u2qvLvWPHE9xpSRdgnpa35.zip) (252 KB) ---
**Author:** ![peterguthrie](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/peterguthrie/32/57456_2.png) [@peterguthrie](https://forums.chaos.com/u/peterguthrie)\ **Post date:** [November 24, 2014, 7:14pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/23 "2014-11-24T19:14:28Z")
I’m sure that will be really useful (and to others too), many thanks Dmitry. Forgive me if I don’t give more feedback, don’t have time to play around with it right now! ---
**Author:** ![Morbid\_Angel](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/morbid_angel/32/21272_2.png) [@Morbid\_Angel](https://forums.chaos.com/u/Morbid_Angel)\ **Post date:** [November 24, 2014, 7:17pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/24 "2014-11-24T19:17:56Z")
Np. My issue is with a scene like I attached there, it does not scale well to other scenes/projects. If I was to move this light around, scale the plane etc, the caustics will totally change/disappear (what was happening to me in that project). ---
**Author:** ![Neilg](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/neilg/32/7044_2.png) [@Neilg](https://forums.chaos.com/u/Neilg)\ **Post date:** [November 24, 2014, 10:59pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/25 "2014-11-24T22:59:00Z")
I’ve got a pretty reliable method for caustics. It works great on 5k wide+ stills. Obviously it wont work for every situation, but for those it does work for it means i can actually use caustics in a production image which basically just isnt possible given the time any other method takes. ![J2bcYpZ](https://europe1.discourse-cdn.com/chaosprd/original/4X/9/9/0/990acf4da2636e3ac759c105c76a7ce9299cc12e.jpeg) ---
**Author:** ![vlado](https://avatars.discourse-cdn.com/v4/letter/v/779978/32.png) [@vlado](https://forums.chaos.com/u/vlado)\ **Post date:** [November 25, 2014, 8:26am UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/26 "2014-11-25T08:26:42Z")
> [@V-Ray 3.0 for 3ds Max Beta Open!](https://forums.chaos.com/t/v-ray-3-0-for-3ds-max-beta-open/46204/115): > > I’ve got a pretty reliable method for caustics. It works great on 5k wide+ stills. Obviously it wont work for every situation, but for those it does work for it means i can actually use caustics in a production image which basically just isnt possible given the time any other method takes. > > [Imgur: The magic of the Internet](http://i.imgur.com/J2bcYpZ.jpg) That’s a reliable approach if you don’t need to see the caustics through mirror/glass materials. However you don’t need to render several frames. Instead, set the max. density for the caustics to some reasonably small number (2-3 cm perhaps). Then the render will take some RAM, but because nearby photons will be merged instead of simply added to the photon map, it will typically not run out of RAM. Best regards, Vlado ---
**Author:** ![Vizioen](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/vizioen/32/59355_2.png) [@Vizioen](https://forums.chaos.com/u/Vizioen)\ **Post date:** [November 25, 2014, 8:28am UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/27 "2014-11-25T08:28:00Z")
> [@V-Ray 3.0 for 3ds Max Beta Open!](https://forums.chaos.com/t/v-ray-3-0-for-3ds-max-beta-open/46204/115): > > I’ve got a pretty reliable method for caustics. It works great on 5k wide+ stills. Obviously it wont work for every situation, but for those it does work for it means i can actually use caustics in a production image which basically just isnt possible given the time any other method takes. > > [Imgur: The magic of the Internet](http://i.imgur.com/J2bcYpZ.jpg) Indeed very good tutorial for reflective caustics, but how does one tackle refractive caustics then? ---
**Author:** ![Neilg](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/neilg/32/7044_2.png) [@Neilg](https://forums.chaos.com/u/Neilg)\ **Post date:** [November 25, 2014, 4:08pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/28 "2014-11-25T16:08:07Z")
you dont! it’s just to get large scale light patterns to overlay in post later. works real good on external building glass and unique light fixtures - big ones that even a client would notice were missing. Thanks for that tip vlado! ---
**Author:** ![peterguthrie](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/peterguthrie/32/57456_2.png) [@peterguthrie](https://forums.chaos.com/u/peterguthrie)\ **Post date:** [November 25, 2014, 4:36pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/29 "2014-11-25T16:36:27Z")
so refractive caustics arent shown when ‘directly visible’ is ticked? ---
**Author:** ![vlado](https://avatars.discourse-cdn.com/v4/letter/v/779978/32.png) [@vlado](https://forums.chaos.com/u/vlado)\ **Post date:** [November 25, 2014, 5:25pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/30 "2014-11-25T17:25:36Z")
> [@vlado](#): > > so refractive caustics arent shown when ‘directly visible’ is ticked? They will be shown, but only if they are directly visible. Caustics seen through the refractive surface itself will not be. For the spring service pack we are working in a solution for caustics that works well with the progressive sampler and can handle these cases much much better. Best regards, Vlado ---
**Author:** ![Dariusz\_Makowski\_Dadal](https://avatars.discourse-cdn.com/v4/letter/d/c4cdca/32.png) [@Dariusz\_Makowski\_Dadal](https://forums.chaos.com/u/Dariusz_Makowski_Dadal)\ **Post date:** [November 25, 2014, 8:54pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/31 "2014-11-25T20:54:38Z")
> [@vlado](#): > > They will be shown, but only if they are directly visible. Caustics seen through the refractive surface itself will not be. > > For the spring service pack we are working in a solution for caustics that works well with the progressive sampler and can handle these cases much much better. > > Best regards, > Vlado Its a bout time to have a better caustic sollution. I’m so tired of having to change render engine to render efficiently my 9-10k caustic passes ☹ ---
**Author:** ![vlado](https://avatars.discourse-cdn.com/v4/letter/v/779978/32.png) [@vlado](https://forums.chaos.com/u/vlado)\ **Post date:** [November 25, 2014, 10:16pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/32 "2014-11-25T22:16:44Z")
Yes, now that we have the progressive sampler, it is a lot easier to implement multipass caustics compared to the bucket sampler. Best regards, Vlado ---
**Author:** ![Morbid\_Angel](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/morbid_angel/32/21272_2.png) [@Morbid\_Angel](https://forums.chaos.com/u/Morbid_Angel)\ **Post date:** [November 25, 2014, 11:53pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/33 "2014-11-25T23:53:27Z")
finally. my dreams come true. I can render caustics. 😄 ---
**Author:** ![Vizioen](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/vizioen/32/59355_2.png) [@Vizioen](https://forums.chaos.com/u/Vizioen)\ **Post date:** [November 26, 2014, 2:19pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/34 "2014-11-26T14:19:03Z")
> [@Mirko](#): > > The ocean displacement texture that comes with the phoenixFD demo is incredible. You might be able to use it for pool water if you dial it down enough. > > Not pool water but Tommi from work created this for the evermotion challenge using this Ocean texture. The only 'shopped thing about the water are the large splashes near the water’s edge and the grading tweaks… > > Surely this would create awesome geometry for caustics… Tommi from work is Tamas Medve from MIR? ---
**Author:** ![peterguthrie](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/peterguthrie/32/57456_2.png) [@peterguthrie](https://forums.chaos.com/u/peterguthrie)\ **Post date:** [April 14, 2015, 9:35am UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/35 "2015-04-14T09:35:13Z")
> [@vlado](#): > > They will be shown, but only if they are directly visible. Caustics seen through the refractive surface itself will not be. > > For the spring service pack we are working in a solution for caustics that works well with the progressive sampler and can handle these cases much much better. > > Best regards, > Vlado Having to do caustics again and just wondered if there was any news on this Vlado? anything in the nightlies to test yet? ---
**Author:** ![stevesideas](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/stevesideas/32/29103_2.png) [@stevesideas](https://forums.chaos.com/u/stevesideas)\ **Post date:** [April 17, 2015, 9:48am UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/36 "2015-04-17T09:48:58Z")
> [@vlado](#): > > They will be shown, but only if they are directly visible. Caustics seen through the refractive surface itself will not be. > > For the spring service pack we are working in a solution for caustics that works well with the progressive sampler and can handle these cases much much better. > > Best regards, > Vlado I’m curious as to if this solution would include some kind of photon overide for the light so instead of the photons for caustics being cast the same as the photons for diffuse etc you could control a cone that fires them much more tightly/specifically at an area ? ---
**Author:** ![peterguthrie](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/peterguthrie/32/57456_2.png) [@peterguthrie](https://forums.chaos.com/u/peterguthrie)\ **Post date:** [April 28, 2015, 9:53am UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/37 "2015-04-28T09:53:22Z")
just bumping this thread.. and also wondering if there is any way to render the caustics pass without rendering the main rgb pass? ---
**Author:** ![vlado](https://avatars.discourse-cdn.com/v4/letter/v/779978/32.png) [@vlado](https://forums.chaos.com/u/vlado)\ **Post date:** [April 28, 2015, 11:40am UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/38 "2015-04-28T11:40:19Z")
> [@peterguthrie](#): > > and also wondering if there is any way to render the caustics pass without rendering the main rgb pass? If you only want the directly visible caustics, turn on the “direct visualization” option and then turn on “don’t render final image”. Best regards, Vlado ---
**Author:** ![peterguthrie](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/peterguthrie/32/57456_2.png) [@peterguthrie](https://forums.chaos.com/u/peterguthrie)\ **Post date:** [April 28, 2015, 6:53pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/39 "2015-04-28T18:53:56Z")
> [@vlado](#): > > If you only want the directly visible caustics, turn on the “direct visualization” option and then turn on “don’t render final image”. > > Best regards, > Vlado unfortunately its caustics through water so no directly visible, unless there are some tricks like not renderable geometry or something? ---
**Author:** ![Neilg](https://dub1.discourse-cdn.com/chaosprd/user_avatar/forums.chaos.com/neilg/32/7044_2.png) [@Neilg](https://forums.chaos.com/u/Neilg)\ **Post date:** [April 28, 2015, 7:20pm UTC](https://forums.chaos.com/t/caustics-for-idiots/49961/40 "2015-04-28T19:20:18Z")
I’ve done that a few times. Turn off the water, render the caustics on black, camera project it back onto the object in an additive mode and render the full image with the water on. [Previous page](https://forums.chaos.com/t/caustics-for-idiots/49961.md?page=1) [Next page](https://forums.chaos.com/t/caustics-for-idiots/49961.md?page=3)