Vray renders blurred images faster. WHY??

[YOHKOH]

I find that if i blur my textures in photoshop, they render a hell of a lot faster. Good for quick images and animation but i'm wondering why they should render faster. Doesn't max/vray just read an image as an image regardless of what the image is of.

 

It also renders faster if the original photo is blurry/out of focus.

 

Any thoughts anyone??

Edited April 8, 2009 by YOHKOH

[WAcky]

I would say its probably because there is less colour contrast between each pixel, its much easier for the sampler to work through.

 

If you set your sampler to fixed is there still any variation?

If you blur your bitmaps using max does it change the render times?

 

Would be interesting to see what the guys at the chaosgroup forums think...

 

perhaps play around with your clr threshold. It seems to determine how much pixel contrast is seen by the sampler.

 

From the help files:

Color threshold - the threshold that will be used to determine if a pixel needs more samples. This is ignored if the Use DMC sampler threshold option is on.

[YOHKOH]

Blurring the image from within the material editor actually increases render times. Default blur is always one and I usually set it to close to zero.

 

If using fixed sampler there is i find no difference in render times when the images are blurred or not.

 

Just changing the clr threshold made a massive difference to render time. From 55sec down to just 7s with barely noticeable degredation in quality. (I'm testing on a simple scene with a bitmap on a box and simple lighting)

 

Rendering geometry with high contrast areas and lots of details, eg aluminium ventilation louvres on a facade, produces very noticable degrading of the image when changing the clr thresh.

 

But if your baking your facades and just apply images then its worth a look.

 

 

Even just for maps which are in the background and you are going for depth of field anyway.

Edited April 8, 2009 by YOHKOH

[Mr-JosE]

If you're rendering textures try and use the ADMC sampler. Its better orientated for this type of render compared to the AS sampler.