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View Full Version : Depth Buffer Antialiasing... where?



Mattoo
08-24-2003, 02:42 PM
Does anyone know where this is?

I remember looking for it a while back but now I really could use it.
The 7.5 manual says it should be a pixel filter plugin but I just can't see it.

Anyone got any ideas?

Doug Nicola
08-24-2003, 03:16 PM
1. Do Alt-F9 to configure keys.

2. open the "Effects" group

3. Assign hot key for "Depth Buffer Antialiasing"

4. Run hot key command to get dialog box.

The manual doesn't say it's a pixel filter, but talks about how the pixels are manipulated with this AA. And it mentions the "Effects command group," which is not the Panel, but the configure keys (or menus) command group. Kind of confusing...:)

Mattoo
08-24-2003, 03:33 PM
Ah I see, yes very confusing, not very clear at all. I should be able to find it now thanks!

Mattoo
08-24-2003, 03:56 PM
I've set it to both minimal and average yet it makes no difference to the final output of the depth buffer.

Is this something that only effects the RLA/RPF savers?

Doug Nicola
08-24-2003, 05:35 PM
The depth buffer AA is not about smoothing the depth buffer image (which it doesn't do... EDIT: Wrong! It does indeed!...) but about controlling Z depth information only. And it can make a difference with what shows up in your depth buffer when you are dealing with fine detail.

Here are two depth buffer images as examples.

This is a fine/thin detail image with the default "Minimum" depth buffer AA setting (with enhanced high AA):

Doug Nicola
08-24-2003, 05:37 PM
Here is the depth buffer with the "Average" depth buffer AA setting:

Doug Nicola
08-24-2003, 05:39 PM
As you can see, averaging the pixel AA depth info has wiped out the fine detail, and will create an incorrect result, in this case.

But in another case, you may need the averaged depth result, I suppose.

The "depth buffer AA" info comes from every AA pass, when the pixel is given a depth value. This can change from pass to pass, as the AA routine samples the image, makes changes, and finds different values. The "minimum" setting uses the closest Z depth value from these passes, and the "average" setting takes the average Z depth value. So it's really about Z depth only, not AA (more confusion!).

Also, you can get the depth buffer with the Buffer Export plugin or the RLA/RPF, or whatever else exports it.

Doug Nicola
08-24-2003, 06:17 PM
Of course, "smoothing" the depth buffer in an AA way wouldn't make sense, as that would really mean depth values all over the place!

Here's another example to show that nothing is getting "smoothed" out. This is with the "Average" depth buffer AA setting, and enhanced high AA:

Mattoo
08-24-2003, 06:43 PM
Ok, I'm beginning to understand thanks.

I actually tried it with the DepthBuffer set to Average and it did help reduce the halo effect on large contrasted areas in the Z-Depth in DFX.

Thanks for the explaination.

Doug Nicola
08-24-2003, 07:08 PM
Mattoo! I'm wrong! I've discovered what looks like a real antialiasing effect with this... I'll post the example very quick.

Doug Nicola
08-24-2003, 07:15 PM
Here's the default Minimum setting with a ground object in the scene:

Doug Nicola
08-24-2003, 07:16 PM
And here's the same scene with the Average setting:

Doug Nicola
08-24-2003, 07:17 PM
Here it is (oops!)
Note the smoothness where the foreground object overlaps the ground object.

Doug Nicola
08-24-2003, 07:19 PM
So it's really in combination with the particular additional information in your scene (like you mentioned above) where this can come in handy.

Mattoo
08-24-2003, 08:07 PM
Ok, that explains why it looked better in the areas that didn't border the background colour, I hadn't noticed that.

I'll carry on playing with it, see if I can come up with something I'm happy with.

Cheers Doug.