Some Vray help please

solo

I am trying out Vray trial and decided to 'actually' try it this time, however I need a few answers from any seasoned user.

How do I set it up so that it renders at a decent speed and not look so 'grainy'? (exterior)

My shadows look kinda blue, I know it can be corrected in PS, but is there a way to render shadows correctly? I changed the color of sky to white, yet it's still blue in render how's that?

Thanks.

thomthom

You're using the latest available at their site? SR 1.5 (v1.05.30)

If you're using default settings you're probably using DMC for either one of your light engines. DMC is accurate, but slow and noisy.

Here's what I recommend:

Primary Engine: Irradiance Map
Use default settings for OK final results.
For testing:
Min Rate: -3
Max Rate: -2
HSph. Subdivs: 25
Samples: 10

Secondary Engine: Light Cache
Subdivs: 250
Num Phases: 2
Ticking "Use For Glossy Rays" might help if you have a bit of glossy reflections.

The Irradiance Map (IR) might be a bit blotchy some times. Ensure that DMC Sampler's Adaptive Amount is set to 0.85. (Makes things slightly slower, so for very quick and dirty renders you might want to increase it, but 1.0 is never a good value.)

Set Image Sampler to Adaptive QMC for final renders, Adaptive Subdivisions for tests.

Reflection/Refraction Max Depth will affect the speed, but also impacts the light and transparent materials.

As for your blueish colour caused by the sky, it'd be good if you could post and example here.
But you could try to increase the Turbidity. Lowering the Ozone might help a little as well. See the examples at spot3d for a visual reference: http://www.spot3d.com/vray/help/150SP1/examples_vraysun_sky.htm

thomthom

hmm... are you using a colour for your Enviroment Background, or the Sky map?

solo

No sky map, using default setting, just changed the blue color to white using the color pallette with no avail.

Gonna sound silly but wtf is 'DMC'? (with stupid questions like these I should rather walk away before embarrasing myself...too late...)

thomthom

To be honest, I've got no idea what it stands for. I just know that DMC is one of the options for the Light Engines. (Used to be QMC in the original V-Ray)

Stinkie

"Monte Carlo (MC) sampling is a method for evaluating "blurry" values (anitaliasing, depth of field, indirect illumination, area lights, glossy reflections/refractions, translucency, motion blur etc). V-Ray uses a variant of Monte Carlo sampling called deterministic Monte Carlo (DMC). The difference between pure Monte Carlo sampling and deterministic Monte Carlo is that the first uses pseudo-random numbers which are different for each and every evaluation (and so re-rendering a single image will always produce slightly different results in the noise), while deterministic Monte Carlo uses a pre-defined set of samples (possibly optimized to reduce the noise), which allows re-rendering an image to always produce the exact same result. By default, the deterministic Monte Carlo method used by V-Ray is a modficiation of Schlick sampling, introduced by Christophe Schlick in 1991" - source: spot3d.com

That clear? I guess we could just say it's a brute force calculation method. Use it when your scene has lots of details. If not, leave it alone. IR Map + LC should be sufficient in most cases.

I'm no expert at Vray, far from it, but so far I've learned that the visopts you can download from the Asgvis site prove great starting points. So far, I've been getting pretty decent results with those - and some, but not much, tweaking. (Changing the ISO, the hemispheric subdivisions etc)

Also, do read the manual, it does a pretty decent job at explaining a lot of things. Not 'a good read', but a useful one nonetheless.

AFAIK, it is pretty much impossible to get rid of the blue cast when using the physical sky. I could be wrong though!

Have fun with Vray. It's a good app.

DzineTech

Solo,

The blue shadows problem is something that cant be cured as unfortunately VfSU doesnt have the flexibility that Vray for Max has when it comes to being able to add a vray sun/sky - it uses the SU sun and gets its skylight from this as well. What this means is that in VfSU the skylight contribution bleeds onto the scene whereas in max we can counter this via an vraysky in an output map.

In addition to what Thomthom said

@thomthom said:

Primary Engine: Irradiance Map
Use default settings for OK final results.
For testing:
Min Rate: -3
Max Rate: -2
HSph. Subdivs: 25
Samples: 10

Secondary Engine: Light Cache
Subdivs: 250
Num Phases: 2 Set this to match the no. processors on your CPU
Ticking "Use For Glossy Rays" might help if you have a bit of glossy reflections.

The Irradiance Map (IR) might be a bit blotchy some times. Ensure that DMC Sampler's Adaptive Amount is set to 0.85. (Makes things slightly slower, so for very quick and dirty renders you might want to increase it, but 1.0 is never a good value.)

Set Image Sampler to Adaptive QMC for final renders, Adaptive Subdivisions for tests.This is a generalisation as it depends on the type of scene and its geometry for what image sampler is best suited.

Reflection/Refraction Max Depth will affect the speed, but also impacts the light and transparent materials.This setting = no. faces that light is permitted to pass through as seen from the camera

As for your blueish colour caused by the sky, it'd be good if you could post and example here.
But you could try to increase the Turbidity. Lowering the Ozone might help a little as well. See the examples at spot3d for a visual reference: http://www.spot3d.com/vray/help/150SP1/examples_vraysun_sky.htm

solo

Thanks for the help guys, I have a long way to go, not sure if I will be fluent by time the trial ends, but certainly will give it a good go.

Here is what I have so far, still needs a lot of texture work and a few more components to be added, but I am happy to get past the grainy look.
The modeling was fast, about 4 hours, the texturing is gonna be longer as every wall needs to be done seperately in order to achieve to white washed with a little mold look.

Click Draw

Hey Pete,
I just e-mailed you the Manuel I found....pretty good.
Jeff

DzineTech

Pete, thats a very god start. If you want your verticals to go perpendicular to the horizon, you need to adjust the len shift value in the physical camera. When I was using VfSU, I would start with about 0.1 for a shot from ground eye-level. Quickest way to get this right is to tick the material override and reduce the render output size whilst you test out which lens shift value gets your verticals upright.