Hsph. subdivs and Samples Ratio

[inevitableavoidance]

When increasing the Hsph. Subdivs, I should increase the samples as well, right?

Is there some kind of equation to determine the ratio between these two?
What should the ratio be like?

[MoonDoggie]

You can increase them independently, safely. I often go up to 120 hsph, and interp samples: 30 (probably don't want to go too much higher on the interp samples or your solution will get too blurry.).

Hope this helps .

Here's the manual:
http://www.spot3d.com/vray/help/200R...vancedimap.htm

[inevitableavoidance]

What min rate, max rate, and thresholds do you use with that? And how would you set your settings for preview-renders? I'm getting a blotchy result, and the rendering isn't fast at all at the moment.

[MoonDoggie]

For a quick render, just toss on the low/medium preset. I barely ever touch the thresholds at all. Since it's dependent on resolution, for a 900x506 (my preview render usual size, same aspect as 1280x720) I use like -4/-3 for super quick renders.

[inevitableavoidance]

I don't think I have presets here..
Did you mean that the thresholds are dependent on resolution, or the min/max?
And how does resolution affect it?

Thanks a lot for your information so far!

[MoonDoggie]

No problem. I don't use sketchup, but I should still be able to help.

IMAP calculation is dependent on resolution. For instance, in max, the high preset is -3/-1. The -1 means to render the highest pass of the imap (the max) at half the resolution as the final image.

As you increase the resolution of your image you can decrease these values by -1 everytime you double your resolution. So for a low HD image (1280x720). I use -3/-1. If I go to 1920x1080 then I use -4/-2. A really big render 3000x1500, I drop it to -5/-3. The thresholds are as well.

It all depends on your scene. Scenes with lots of detail will require higher hsph. subdivs.

The best way to do this process is to add the render element "VRayGlobalIllumination" and to look at it only isolating it from your RGB render. Make sure it looks nice and smooth. Change a value, compare, and re-render. Hopefully this will help. Post a render, show us your VRayGlobalIllumination render and maybe we can help.

-Colin

[andybot_cg]

The best way to do this process is to add the render element "VRayGlobalIllumination" and to look at it only isolating it from your RGB render.

good suggestion. In vfsu, this can be found in the vfb channels in the options - select the "GI" channel. When you save your image, you'll have one file with just the GI.

Edit: actually, probably want to use "raw GI" - the GI pass shows the diffuse layer as well so it's harder to see the quality of the GI.

[MoonDoggie]

good suggestion. In vfsu, this can be found in the vfb channels in the options - select the "GI" channel. When you save your image, you'll have one file with just the GI.

+1, thanks for the relevant information for sketchup.

[andybot_cg]

Here's an example

[MoonDoggie]

Ahh, I can't see them because I'm not authed to this forum to view stuff. Still no idea why seeing an image from sketchup would be a problem for chaosgroup. At any rate, Any chance you can post it to imgur.com? or something.

This brings something up that bothers me about this forum. I can't see Phoenix FD stuff posted on the forums. I would love to see what people are doing with Phoenix and it might help me to purchase it. It's fine. It's their choice for a reason, but I don't understand the logic behind it.

Post it to an image sharing site if you don't mind and I'll check it out.

[andybot_cg]

imageshack:
render:

GI channel

Raw GI channel (Levels are adjusted in the vfb, otherwise the image is too washed out.)

This brings something up that bothers me about this forum. I can't see Phoenix FD stuff posted on the forums. I would love to see what people are doing with Phoenix and it might help me to purchase it. It's fine. It's their choice for a reason, but I don't understand the logic behind it.

I agree - for example, I'd like to see images in the Rhino forum, since it's the same program as the vray plugin, but no permissions there. I don't understand the reasoning either. If someone's a registered user of vray, why restrict viewing permissions? (and only selectively, I can see images in the max forums...)

[MoonDoggie]

Your GI looks smooth, but too hot. For something like this, where you have no really crazy high frequency details, you can lower your irradiance map a lot. If you were trying to get GI details for something like this:
you would need better settings.

-3/-1 hsph: 50, interp: 20, clr thresh: .4, norm thesh: .2, dist thresh: .1

(these are the defaults for max's medium setting). Shouldn't need to go any higher at all. If there's issues you're concerned about it's probably because of another reason, Direct light noise, Reflection noise, low LC subdivs, etc. Are you just trying to get the quickest render or troubleshooting a problem at this point?

[andybot_cg]

Your GI looks smooth, but too hot.

This is just a quick exterior, the exposure is for daylight, so the GI isn't adding a whole lot to the scene. I haven't really used the GI pass before, what I do typically is run a clay render, or sometimes check the option to calculate GI only.

I usually use 70 for the Hsph, doesn't add much time to the render, but usually helps with the smoothness.

[andybot_cg]

Here's an example with more GI

[MoonDoggie]

Ok, you're getting large blotches for your GI. It looks like you aren't getting decent sampling from the windows. Do this for me real quick. I apologize if they aren't clear because they aren't vfsu specific.

Select all your windows and turn them off to GI.
Place VRayLights just outside the windows, the same size as the windows (slightly bigger), set them to "Skylight Portal" and "Simple".

Re-render using the same settings and let's see.