How to take care of Alpha masking?

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vanlicht
Licensed Customer
Posts: 139
Joined: Fri Feb 26, 2010 8:19 am
Location: Los Angeles

This question was mentioned before and [gk] and some others suggested a solution by rendering out black and white image,
treating it as the alpha mask.

Though, here the picture also has the depth of field blurr, plus the reflection. I guess that's where's it spoils the plan,
or at least I have trouble figuring out the solution.
Attached are three pictures:

The first one is the alpha mask.
The second one is the beauty pass itself.
The third one is the composited one with a background sky picture.


If anyone have a solution how to get rid of that white rim (which was supposed to be the blurr + reflection area),
that would be more than wonderful.

ps. The corner at the alpha picture there's bit of vignetting. it's actually a sky color of blue. I have the sun direction
and lighting power remain exactly the same...and that's why there's bit of blue at the top left corner. If I change the lighting
to rgb texture instead, I can get the pure white background, but the degree of blurr in the edge would be different.


Thomas
Attachments
sc01_alpha_v001.0001.png
sc01_v001.0001.png
test001.jpg
Windows 7 64bit | Maya 2010 64 bit (main) | Maya 2011 | Intel i7-920 | Nvidia Quadro FX1800 | Nvidia GTX480
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kubo
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Joined: Wed Apr 21, 2010 4:11 am
Location: Madrizzzz

There is several things you could do, first would be to add more contrast to the clip image playing with the tonemapper or the intensity of the background, another would be lowering the aperture also in the clip only, or at comp (at least in photoshop) there is this tool to eliminate white halos)
Nice image btw
windows 7 x64 | 2xGTX570 (warming up the planet 1ºC at a time) | i7 920 | 12GB
vanlicht
Licensed Customer
Posts: 139
Joined: Fri Feb 26, 2010 8:19 am
Location: Los Angeles

Hi Kubo thanks for replying.
I am not sure what tonemapper you refer to...is there a button called tonemapper?
Also, would appreciate if you can try solving the problem using those pictures I provide.
I asked my compositor friend and he said the "alpha map" I rendered out isn't really working with the image.

cheers,
Last edited by vanlicht on Fri Aug 27, 2010 8:06 am, edited 1 time in total.
Windows 7 64bit | Maya 2010 64 bit (main) | Maya 2011 | Intel i7-920 | Nvidia Quadro FX1800 | Nvidia GTX480
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foxid
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Its not alpha as it is...its emitation of alpha. And camera options also influence. Its not correct. Need fair alpha algorithm.
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kubo
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Foxid is rigth, this is just a "trick", true alpha maps are on its way, but in the meantime...
Well, what I meant is to render again the "alpha" one, and in the preview imager eliminate the vignetting, play with the exposure, and the rest of the values to get a more suitable image. Also in the enviroment set a higher power.
windows 7 x64 | 2xGTX570 (warming up the planet 1ºC at a time) | i7 920 | 12GB
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