PDA

View Full Version : Caustics lw2018



Mats Andersen
01-27-2018, 02:55 PM
Hi

Anyone been able to find a vid on caustics? I have hardly been able to do any caustics at all. Must be an important button I have not clicked yet.

Radiosity is on etc.
What are the requirements to light sources?
I only get very very noisy and slow results...

best regards
Mats

erikals
01-27-2018, 04:42 PM
you might want Gi interpolated,
bit more on that >
https://docs.lightwave3d.com/display/LW2018/Global+Illumination+tab

Caustics is generally slow to compute, haven't tried it in LW2018 though

Mats Andersen
01-28-2018, 09:42 AM
Hi and thanks for the input! Not much wiser - I have tried mostly with lights, and simple test scenes. Previous version handled it via the settings intensity/accuracy and softness. That was at least easy to relate to.
Since these setting are not anymore there I am thinking it has to be replaced for something better - I havent found it yet and miss it now hehe.

Is it still required to model glass like in the old days with two materials? inside and outside? Can it be the models that are causing the problem? I have also tried with a simple glass ball object.
It seems thata backdrop needs tobe enabled. I want to make like a black room scene with a few glass obejcts on a table and a simple lightsource. A classis test.

Mats

erikals
01-28-2018, 09:53 AM
i too did test a bit but didn't get satisfying results,

for glass, no need for "air-polys" anymore :)
just use a dielectric node and you should be good to go.
usually no, the objects do not cause the problem.

i wish i was better at it, but maybe someone can help? maybe the LW content folder provide a sample scene?

heading out the door in 5, but maybe check this link below, some are discussing caustics over there...
http://forums.newtek.com/showthread.php?155498&p=1535216

RebelHill
01-28-2018, 10:06 AM
Like this...

Mats Andersen
01-28-2018, 02:20 PM
Thank you.

In the meantime though i have figured out a few things.

- It does not work on point based lightsources, such as good old point light or spotlight. It needs a light source with a certain area. Such as spherical or area etc. The larger the light area the more samples. Does seem to help just adding samples. it is the size of the light area/object that determines smoothnes. Antialiasin is the second parameter that hugely influence caustics smoothness and the the thrid being the radiosity brute force samples.

For intensity its naturally the light source intensity or the radiosity intensity that will boost it.

Interpolation is not very effective as you need very small pixel spacing sampling to get a decent result. then it seems faster just doing brute force and a little more antialiasing instead.

Mats

Rayek
01-28-2018, 02:49 PM
It has been mentioned in another thread that Lightwave 2018's path tracer is uni-directional, and not equipped for fast or good reflective or refractive caustic effects. A shader to fake quick caustics is still missing, but perhaps someone will come up with one (in the other thread a custom shader is said to be worked on).

erikals
01-28-2018, 05:12 PM
yes, do check the other thread, some info there on LW2018 caustics
http://forums.newtek.com/showthread.php?155498&p=1535216

jbrookes
01-28-2018, 10:46 PM
I'm also having issues getting caustics to work. I tried bringing in a scene from LightWave 2015 over to 2018. I went in and checked Caustics in 2018, but I don't see any effect. Maybe I'm missing something obvious?

I've attached the 2015 scene and objects in case anyone wants to try it out (along with a few renders to show the comparison between 2015 and 2018 that I'm seeing so far). Hopefully it's just a case of user error on my part.

Rayek
01-29-2018, 12:32 AM
I'm also having issues getting caustics to work. I tried bringing in a scene from LightWave 2015 over to 2018. I went in and checked Caustics in 2018, but I don't see any effect. Maybe I'm missing something obvious?

I've attached the 2015 scene and objects in case anyone wants to try it out (along with a few renders to show the comparison between 2015 and 2018 that I'm seeing so far). Hopefully it's just a case of user error on my part.

As has been explained in the other thread, caustics in 2018 only work with some light types. Being a Monte Carlo unidirectional path tracer, caustics are slow to render and not very nice to look at in LW2018. It requires either a bidirectional path tracer or other "trickery" (fake caustics glass shader, for example) to render nice and quick caustics.

If you are looking for good caustics in the current LW2018, you will be disappointed. That said, it is the same in other unidirectional path tracers, such as Cycles and Octane. Good ones can be had with render engines like Lux Render, Indigo, Yafaray, Maxwell, etc.

jbrookes
01-29-2018, 11:58 AM
Has anyone found a work-around or is the final verdict that we've effectively lost caustics in LightWave 2018?

Is the new render engine in LW 2018 a step back or is there enough there to clearly say that it's superior to the LW 2015 render engine?

erikals
01-29-2018, 01:03 PM
LW2018

- PBR
- FiberFX improved render quality
- Volumetrics major improvements

it is better, though not so much for caustics perhaps.

maybe someone wants to create a LW2018 caustics shader (hint-hint) :)

Mats Andersen
01-31-2018, 01:28 PM
Has anyone found a work-around or is the final verdict that we've effectively lost caustics in LightWave 2018?

Is the new render engine in LW 2018 a step back or is there enough there to clearly say that it's superior to the LW 2015 render engine?

Check my psot a few posts further up. It works fine, you only need to use lights that have area. not point og spotlights.

M