Help Matching Scenes

[jscarr]

Hi everyone,

Hopefully you're not all tired of things like this. I'm primarily an fR user but want to educate myself about Vray so that I can translate scenes more accurately. Learning the various settings in each program and figuring out how they're used shows how each plugin deals with things differently. Quite eye opening.

Anyway, here's the scene:

1) simple boxed in room (with render specific material)
2) orange glass ball (with render specific material)
3) two lights
-one pointing at ceiling with strong value
-one pointing directly at glass ball



Render times are not an issue right now. What I'm really trying to do is understand what I need to change so that:

1) the Vray glass ball has brighter specularity and overall more brightness in the material itself.

2) the Vray ball emits more caustics to the right, as shown in the fR image.


That's it! As you can see the contrast in of the walls and floor is really, really nice in the Vray image. I'll be checking with the fR folks to see how to improve theirs.

One note, I know changing the lights' multipliers will affect things but I'd rather leave them as they are since they're the same in both scenes. The fewer options required to change when translating scenes the better.

Thanks!
-Joe

The Files

P.S. The files contain an fR scene, a Vray scene, and the comparison picture.

[flipside]

Looks like you have GI refraction caustics ON in the vray image and OFF in the fr image. What you see underneath the ball in the vray image are GI caustics, this is on by default in vray, and it's not in fr.

So to have normal caustics (=caustics from direct light, for example spots) in your vray image, you need to set everything correct in your object and light properties. Check vray.info for a tutorial on how to set up caustics in vray.

Play with the reflection amount in your glass mat to have stronger reflections. Do you use fresnell? Maybe turn fresnell off, and use a fallof map with custom curve as a map in the reflection slot. You have more control over the falloff that way (don't use fresnell in the falloff map options, just use the curve for ultimate control )

Your vray glass is darker because the environment that refracts (and reflects) in it is darker. Just look at the walls. Use some more bounces maybe to brighten up the room. Also use the fog color for glass mats, it's great. Black diffuse, white refraction, reflection as said and colored fog with usually very low values, gives very good glass.

Hope this helps

flipside

[jscarr]

Hi Flipside,

Thanks for the response -- sorry for my delay.

GI Refraction caustics are indeed on in both images. What's funny is that it's the top light which causes the most caustics in the Vray image and the direct light for the fR. I've checked the individual light settings and there's nothing too apparent. Strange.

I went through all the caustics tutes on Vray.info and watched the new videos, but nothing was out of the ordinary.

The falloff map for the Vray glass reflection and the fog color definitely helped, thank-you.

Unfortunately no one appears to have interest in downloading the file and checking it out. Thank-you for the suggestions, though.

Kind regards,
Joe

[flipside]

I had problems with your file so I merged it into a new one.

-Go to system rollout and press 'lights settings'
-Click on spot2 in the list
-turn generate caustics on and set multiplier to 8000 (it needs to be this high because the light is a max light and not a vray one)
-set caustic subdivs to 400 for fast tests (set to +-1000 for better renders)
-go to caustics rollout
-enable caustics
-set max photons to 20
-don't enable caustics for the spot1, this doesn't cast direct light onto the sphere so this will not influence the caustics. Because the light illuminates the scene with its second bounce this spot will only generate GI caustics
-I would also suggest to turn on shadows for your lights
-make the fog color the same orange as your refraction color and then make refraction pure white. The affect shadows will no longer have any effect if you have caustics enabled (don't know if it's a bug, but the caustics will color your shadows now, so you don't need the affect shadows option.)
-glass ior is usually 1.5, not 2.5 like in your material
-enable GI
-hit render

the generate diffuse in the lights settings has only an effect when you use photon mapping for GI, this has nothing to do with caustics

I think you have GI caustics turned OFF in your fr example, not ON.

[jscarr]

Flipside, you're a hero - thanks for checking out the file (and especially for the follow-up image - looks great!)

I see the multipliers for Max lights need a bit more power. Good to know, thanks.

hmm, GI Caustics is definitely on in the fR image... you can see the effect off to the right, and the settings:



Thanks again, man! I really appreciate the help!
-Joe

[flipside]

hmm, GI Caustics is definitely on in the fR image...

Ok, just use vray then

glad I could help

flipside

[jscarr]

lol -- maybe when Aura comes out... and if they're still running the 30% for fR users! lol!

thanks, man!
-j

[vlado]

-make the fog color the same orange as your refraction color and then make refraction pure white. The affect shadows will no longer have any effect if you have caustics enabled (don't know if it's a bug, but the caustics will color your shadows now, so you don't need the affect shadows option.)

It's not a bug, it's intentional

Best regards,
Vlado

[flipside]

Hi Vlado,

I understand that the affect shadow option is kind of a fake caustic thing, but sometimes it's a pain if you only have one object that should cast caustics. If you then have for example a window or some other glass objects in your scene, you must enable caustics for them too, because otherwise they will cast black shadows.

regards,

flipside