aliased shadows

[proces2]

I am having a problem with editable splines (with enable in renderer turned ON) casting aliased shadows onto a surface. the surface is a matte object with alpha contribution set to -1.0 and affect shadows and affect alpha turned on.

has anyone else had problems like this? any solutions?

i am using MAX 8 with Vray 1.5 RC3

thanks,
sean

[DaForce]

Hmmm how big is the renderable spline? is it rather small in the render?

Can you post an image of the problem?

[proces2]

this first image has nothing in the background - you can see that there are already some aliasing / banding effects. the renderable splines are very thin. each strip has about 6 individual rods:


this image shows the 'aliasing' but after thinking about it and doing some testing, i don't think it is an aliasing problem (at least for the shadows). its because the shadow is being seen between the rods - it makes it appear aliased.: (seen in the bottom middle of the image)


so at this point - any suggestions on how to fix the problem seen in the first image? do i need to just render the scene larger so there are more pixels to create the rods?

sean

[proces2]

higher-res definitely shows that the shadowing is in fact right. but, i still get the banding when one set of rods overlaps another.


i have never tested the different AA filters - suggestions of one over another? would it even help?

sean

[DaForce]

hmmm weird.

For testing try the following.
QMC AA 1/15
no AA filter

See how it looks.
Perhaps just use region render so you dont have to render the whole thing again.

[proces2]

no luck unfortunately.


this is with the settings that you just mentioned (using QMC 1/15)

sean

[Paul Oblomov]

I don't think it can be avoided at all.

[DaForce]

hmmm the banding that you can see seems to happen in the refraction of the splines. Maybe that could atleast by fixed by increase the max depth of the refraction and reflection (may as well)

As for the AA problem...hmmm I dont think it can be solved by changing the AA filter, but you could try Cook variable and maybe Mitchell-Netravali

[proces2]

its actually a solid material assigned to the lines (material with glossy reflection but 'trace reflection' turned off). if its a solid material do the max depth and refraction and reflection have any affect?

sean

[DaForce]

hmm if they are solid no transparency or opacity then no the max depth wont have any affect.
Although to me it does look like they are made of glass... especially in the bigger render you posted, it seems you can see thru to the lines behind them.

Could you try just with a plain gray vraymaterial on them and see how it renders, perhaps just drop it in the mtl override slot.

[RErender]

Maybe it is the smoothing? might try an edit poly/mesh and reset the smoothing. Or perhaps normalize the spline.

[vlado]

but, i still get the banding when one set of rods overlaps another.

This is because of the specific way the rods overlap from this camera angle. If you were to build the structure and actually look at it, you'll probably see the exact same thing. It's like when you look at two fine grids one over another with slight rotation - you'll see "aliasing" in real life.

In short, since in this case it is a real-life effect, you will not be able to remove it.

Best regards,
Vlado

[studioDIM]

In short, since in this case it is a real-life effect, you will not be able to remove it.

I may be an utter fool, but this is precisely why i dig VRay

Lele

[percydaman]

Im afraid I had the exact same response to the image. Ive seen that happen in real life many times. I wasn't about to go out on a limb and say it until the expert did first though hehe

[rdg]

Isn't this 'real-life effect' called 'Moiré' ?
Or are you talking about something else?

Georg