Changing 3ds max's bitmap bluring default...Vray's AA

[Neilg]

p.p.s.: even summed area filtering does a better job than pyramidal at the cost of memory. and that's always been there.

4x as much memory as none. the point was that pyramidal at 1.0 is crap and you tried to say it wasnt and people just arent using high res enough maps.

[Joelaff]

Yeah, you are right. Max's pyramid really is pretty crappy at glancing angles. I had always just used SAT in cases where it looked bad in an animation. The elliptical is much better. We've been loading everything with VRayHDRI for over a year now. So it's a no brainer to switch.

Never had much luck with no filtering. Textures got moire patterns and sizzled.

[^Lele^]

4x as much memory as none. the point was that pyramidal at 1.0 is crap and you tried to say it wasnt and people just arent using high res enough maps.

You may read what you wish in the stuff i write.
Yet, there's a benefit in writing things down, in that they can be picked up and reread at will.

The rule is simple: if a texture looks blurry when filtered, its resolution is too low for the intended use.

Too low a texture resolution once projected on screen (as the vanishing point will compress it anisotropically, as opposed to the isotropic scale in my example above).

And just so you can take your anger at someone better than I, here's a quote from this page:
http://en.wikipedia.org/wiki/Anisotropic_filtering

If we need to texture a horizontal plane which is at an oblique angle to the camera, traditional MIP map minification would give us insufficient horizontal resolution due to the reduction of image frequency in the vertical axis.

Slap 64k textures on a slanted plane, for what i care, and giggle all the while thinking i wrote it wrong, i won't lose sleep on it.

As for the filtering switched to elliptical: convert standard bitmaps to VRayHDRI with the RMC menu chaosgroup provided (in max.).
then simply run this line of code:

for m in getclassinstances vrayhdri do m.filterMode=1

Feel free to drag the line of code from the MXS editor to a toolbar to conveniently create yourself a macroscript with button.

As for elliptical filtering, here's a video from an old, and excellent, XSI production DVD set.
The actual VRay implementation may be slightly different, while the concept isn't.
https://www.youtube.com/watch?v=6UNU1pYE6bY

[glorybound]

Three things you can't talk about in the office. Religion, politics, and VRay setting - gosh, relax!

[Joelaff]

Three things you can't talk about in the office. Religion, politics, and VRay setting - gosh, relax!

Don't get me started on Image Filters! (Soften FTW)

[glorybound]

My laymen understanding is, you don't want sharp textures because even the best camera lens will blur things. Also, VRay will render faster when the texture is blurred because it samples pixels and slows when there is high contrast. When you blur a texture map it softens the pixel contrast. Now, why everyone started turning off filtering is a mystery to me. Heck, if someone says that if you cross your eyes and pat your head, Vray will render faster, people will start doing it.

[Joelaff]

I think the render speed effect is not major, and likely scene dependent. In fact most of this is scene dependent. Some textures may look fine with filtering off, some like crap.

For stills it doesn't matter. Whatever looks good.

We will be using elliptical as the default because it provides a nice balance. It is perhaps a hint too sharp at 1.0, with 1.05 or so looking a little better for animations to me. Yes, you can and should blur things in the post, but blurring won't get rid of moire patterns rendered into the image.

Neilg has a great point about how terrible pyramid looks at glancing angles. This would not work well for product shots, or anything where you need fine details. Some other apps handle pyramid MIP mapping better than Max, where it doesn't look so bad at glancing angles (which is where mapping really needed).

As usual, test per scene. Or just adjust anything that looks bad when you render it. In many cases you would never notice the difference due to lighting, the particular texture, etc. Neilg and Lele both show worst case scenarios in their examples... Repeating patterns.

[Joelaff]

Ah, that old video on elliptical filtering brings back fond memories of XSI... Rest in peace. Though I always hated Mental Ray for many reasons. Especially back in the old XSI 5-ish days... MR would crash constantly.

[Macker]

Now, why everyone started turning off filtering is a mystery to me.

Because surely it makes more sense to have the pixel information there, and let the image sampler blur it as necessary rather than simply be presented with a blurry image for the sake of giving the image sampler an easier time?

What I find absolutely baffling is why people do the opposite. They allow these blurry images to be rendered out, only to run a razor sharp Mitchell Netravali filter over them. Madness I tell you.

It's the equivalent of smearing vaseline over your camera lens then running a sharpen filter in photoshop after to fix it.

[Joelaff]

Lol... Using the Mitchell Netravali (or as autocorrect has coined it "net ravioli") filter on anything is hideous

I like a little filtering to begin with, then soften things out with the Gaussian soften filter. This is for VFX. But I could see the sharpness appealing for some still images.

[Lupaz]

Because surely it makes more sense to have the pixel information there, and let the image sampler blur it as necessary rather than simply be presented with a blurry image for the sake of giving the image sampler an easier time?

Not to mention that anything blurry should come from DOF or motion blur (either vray or post), not from blurring the texture.

[Joelaff]

The idea of filtering is not to blur the texture, though. It is to provide a way to sample a larger number of texture pixels into a single image pixel. With large textures and oblique angles, or distant objects, there may be instances where a single image pixel has to represent 100 or even 1000 texture pixels. This makes a lot of work for the ray tracer, and for more extreme cases can't be done in any reasonable amount of time. (Do you really want thousands of eye rays per pixel of your image?). So some filtering is helpful to get that to a manageable level.

I am assuming your textures are higher resolution than their final size in the image. Lower res textures almost alway look like garbage anyway, though scaling them up in a image processing app typically provides better results than letting the renderer do it (filtered or not).

Again, for stills you can easily see if it looks OK and roll with it. Anything goes there, as you won't notice the lack of filtering nearly as much.

But the cool thing about any tool is that people can use it in new and useful ways, creating their own art however they see fit.

[Joelaff]

BTW, as I posted in the Problems section using elliptical filtering in VRayHDRI does not seem to work with displacement in VRayMtl. I get no displacement with elliptical.

[Joelaff]

Here are some cases where turning off filter maps fails. I think the point is that one size does not fit all. You can find test cases where each method fails. You use what you like and then tweak the exceptions where it doesn't work the way you want it to.


Filter Maps Off Area 1.5 (Above)

Filter Maps Off Area 2.5 (Above)

Filter Maps Off Soften 3.95 (Above)

Turning off filter maps produces nasty moire patterns in this case. The soften image filter can almost get rid of it. Area can't touch it.

[Joelaff]

Isotropic Blur 1.0 Area 1.5 (Above)

Isotropic Blur 0.5 Area 1.5 (Above)

Isotropic Blur 1.0 Soften 3.95 (Above)

Interesting how Filter Maps off completely changes the density of the textures.

You can see how even 0.5 begins to produce a moire here, which would be worse in an animation.


Elliptical actually FAILED this test, producing a hideous artifact. (Going to post scene in problems).


Elliptical Blur 1.0 Area 1.5