Can someone pint me in the right direction...

[Ramsay]

I have a bit of free time to learn V-ray properly at the moment and I am trying to get a grasp of irradiance maps.

Can someone explain to me exactly what these settings do?



Cheers guys

Craig

[J_Bug]

Ok, I'm always questioning my knowledge that's why I started collecting the posts located at vray.info so you might want to double check me there but here it goes, anyone, please correct me if I'm wrong:

Any "rate" is referring to sampling, in this case of diffuse bounces.

Min = level of first pass

Max = level of final pass


"thresh" refers to threshold or basically setting a level of detail to process:

Clr = color or hue

Nrm = normal or angle of face relative to surrounding faces

Dist = distance from surrounding faces

"Subdivis" is the way that VRay handles the second bounce in the sense of how many rays are used per sample for the final irrad map.

I've found the presets to be a blessing, especially for tests. The settings you ask about are very powerful and can allow for many situations but if you are just learning you should study the presets Vlado has created on a simple scene. See what they do first then elaborate from there.

--Jon

[Da_elf]

Min rate - this value determines the minimum number of GI samples per pixel. You would usually want to keep this negative, so that GI is quickly computed for large and flat regions in the image. Note: if Min rate value is greater than or equal to zero the computation of the irradiance map will be slower than the GI rendering with the Direct computations approach. VRay will also consume much more memory.

Max rate - this value determines the maximum number of GI samples per pixel.

Clr thresh - when intensity difference between neighboring GI samples exceeds Clr thresh value VRay will take more GI samples.

Nrm thresh - when the cosine of the angle between normal vectors of neighboring samples exceed Nrm thresh value VRay will take more samples.

HSph. subdivs - number of hemisphere samples taken to compute GI.

Interp. samples - number of GI samples per point, stored in the irradiance map.

---copied from the vray help manual-----

[flipside]

Simple rule imo:

test renders: min/max rate = -5/-3, clr=nrm=1, dist=0, hsph=20
This is very fast settings to see the global lighting in the scene

High quality: min/max rate = -3/-0, clr=nrm=0.3, dist=0.1, hsph=50

Clr is the most important from the treshold settings

nrm,clr: low number is long render, good GI detail
dist: higher is longer render (never use this actually, I always use 0.1)

img at 600*400 and min/max=-4/-1 is same GI quality as same img at 300*200 and min/max=-3/0

The direct comp subdivs do nothing imo. The depth lightens up dark areas if you set second bounce multiplier to more than 0.6, but genarally you want to keep this at 0.5 to avoid too much color bleeding. Use exponential color mapping for interiors to lighten up the image, it works great.

regards,

flipside

[Ramsay]

Thanks for the help guys! I will have a play about with the settings today

Craig