Anti-alias multipixel plugin filter

[lhui]

How do multipixel plugin filters work? It takes an input X and Y and outputs a weight, but what does the X and Y stand for? How is X and Y derived?

[joojaa]

You specify the filtering region (in image pixels) and method. Then if the treshold values are exceeded from what the interpolation would expect it forces the renderer to do additional sampling of the pixel until you reach the treshold (a recursion its done again untill its satisfied or untill it reaches the maximum number of allowed recursions, as you might understand this can be very expensive).

The benefit of this is that it can kill flikering that can occour just because the texture samples happen hit certain places. You se just because a pixel is white doesent mean the texture is uniformly white in the pixel.

As aresult youll get slightly more blurred images.

[lhui]

What filtering region? What threshold?

Under Render Globals->Anti Aliasing, you can choose from a list of filters, from Box, Triangle, Gaussian, to plugin. You can also adjust the X and Y pixel widths.

I want to write a mutlipixel filter plugin for this so I can use it when I select it in Render Globals. But I don't understand how this plugin interfaces with Maya...

[deke-kincaid]

sounds like you need to learn more about what multipixel filters are before you try to write a plugin for it. What multipixel filter did you have in mind? Sinc, Catmul Rom?

[lhui]

So where can I learn more about how multi-pixel filters work in Maya?

[joojaa]

Didnt i just explain the basics behind multipix filtering? What the walues are is totaly up to the plugin filter designer, you can even do something rathher stupid if you wish. Bsicaly multipix filtering is a way to instruct maya to do oversampling on a per pixel basis. Usualy tough values are asumed as pixel units (anything else would be wierd, altough sample amounts etc could be acceptable but anything is realy up to the developper.

[lhui]

Nevermind, I figured it out.

What I wanted to now is what did the X and Y values meant, not how to use the X and Y values.

[adreamtraveler]

Right, that would be interesting to know.
Normally blures are based on pixels. However I have never seen a half pixel (0.5). So the numbers are really somewhat strange.

Michael

[joojaa]

Actualy blur is very well implemented for 0.5 values its a question of weighting. Try running gaussian blur with 0.5 in photoshop. Now the idea is not to just blur the image in post but to do a blura and se how much the real result differs from the blurred one and then just oversample if the treshold allowed is exceeded.

In 3d its even better implemented because of the vectorial nature. wich means you can obtain the true 0.5 data if you so wish.