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David Makin
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« on: April 10, 2010, 04:38:29 AM » |
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Hi all, just trying a new ambient occlusion method for the Mandelbox. "New Rome"  If no image above then click the link. |
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Power 8
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« Reply #1 on: April 10, 2010, 05:00:31 AM » |
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Ave Caesar Davidus ! Mandelbox imperator! bravo! very roman indeed!
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knighty
Fractal Iambus
Posts: 819
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« Reply #2 on: April 10, 2010, 06:32:28 PM » |
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Nice picture!  Could we see just the AO effect? |
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Sockratease
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« Reply #3 on: April 10, 2010, 06:42:46 PM » |
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Very Nice!!
But...
Was it built in a day?
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Life is complex - It has real and imaginary components. The All New Fractal Forums is now in Public Beta Testing! Visit FractalForums.org and check it out! |
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Saquedon
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« Reply #4 on: April 11, 2010, 12:58:17 PM » |
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Excellent!  |
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David Makin
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« Reply #5 on: April 11, 2010, 09:50:46 PM » |
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Nice picture! Could we see just the AO effect? The method "Rectagular Ambient Occlusion" was suggested to me by Jos Leys. I've implimented the basic method such that the amount of occlusion at a given point is based on the maximum distance of the poiint from the centre of the cuboid along each axis (x/y/z). I also added an optional directional element. Here the basic method (location based only) on it's own for the "New Rome" fractal:  And here's the enhanced method using the directionality - as applied in the original "New Rome" render:  Note that the jet-black is not errors, it's holes through the Mandelbox to the background Of course the original "New Rome" is made up of the occluded ambient plus diffuse and specular from two light sources. |
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« Last Edit: April 12, 2010, 12:49:23 AM by David Makin »
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Nahee_Enterprises
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« Reply #6 on: April 12, 2010, 04:58:15 AM » |
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Hi all, just trying a new ambient occlusion method for the Mandelbox. This is really cool !!! But something on the "busy" side. Kind of reminds me of the movie "Dark City", when the Strangers would modify the buildings while the people slept. (Looks like a few of yours are still in the process.)  |
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David Makin
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« Reply #7 on: April 12, 2010, 11:13:14 AM » |
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Hi all, just trying a new ambient occlusion method for the Mandelbox. This is really cool !!! But something on the "busy" side. Kind of reminds me of the movie "Dark City", when the Strangers would modify the buildings while the people slept. (Looks like a few of yours are still in the process.) It's only busy at this size - ideally it would be a 40" print or larger  |
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Nahee_Enterprises
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« Reply #8 on: April 13, 2010, 12:53:51 AM » |
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It's only busy at this size - ideally it would be a 40" print or larger Let me know when you have the "full size" image rendered, I would love to see it. |
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David Makin
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« Reply #9 on: April 13, 2010, 03:44:17 AM » |
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It's only busy at this size - ideally it would be a 40" print or larger Let me know when you have the "full size" image rendered, I would love to see it. I don't normally make the full-size versions available So here's a taster, 640*480 detail from the original unresized 3840*2880 rrender:  Of course a 40" print would be from a 12000*9000 render minimum, but I wouldn't increase the detail level any further. |
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knighty
Fractal Iambus
Posts: 819
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« Reply #10 on: April 16, 2010, 05:37:05 PM » |
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Nice picture! Could we see just the AO effect? The method "Rectagular Ambient Occlusion" was suggested to me by Jos Leys. I've implimented the basic method such that the amount of occlusion at a given point is based on the maximum distance of the poiint from the centre of the cuboid along each axis (x/y/z). I also added an optional directional element. Here the basic method (location based only) on it's own for the "New Rome" fractal: /gallery/2/141_11_04_10_9_41_42.jpeg And here's the enhanced method using the directionality - as applied in the original "New Rome" render: /gallery/2/141_11_04_10_9_45_43.jpeg Note that the jet-black is not errors, it's holes through the Mandelbox to the background Of course the original "New Rome" is made up of the occluded ambient plus diffuse and specular from two light sources. Thanks! In case you are interrested, there is an AO technique based on Distance fields that was discribed by IQ in this presentation: http://iquilezles.org/www/material/nvscene2008/nvscene2008.htm |
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« Last Edit: April 18, 2010, 02:42:02 AM by Nahee_Enterprises »
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David Makin
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« Reply #11 on: April 17, 2010, 02:24:12 AM » |
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Thanks for the link.
I confess I haven't looked but I suspect AO based on distance fields requires some sort of screen buffer ?
I need a method that works solely on the information for each pixel in turn so very large renders up to say 12,000 by 9000 are possible in UF (without needing a new 64-bit UF and a 64-bit system).
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knighty
Fractal Iambus
Posts: 819
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« Reply #12 on: April 17, 2010, 04:16:27 PM » |
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No, it doesn't require any buffer.
From the document (p.48):
"The idea: let p be the point to shade. Sample the distance field at a few (5)
points around p and compare the result to the actual distance to p. That
gives surface proximity information that can easily be interpreted as an
(ambient) occlusion factor."
He gives the foll0owing formula:
AO=1-k*sum(i=1;i<=5;2^(-i)*(i*delta-DE(p+n*i*delta)))
p is the point to shade.
n is the unit normal vector at p.
delta is the distance increment for sampling point.
k is a factor for controlling the strength of the AO.
Of course it's a fake AO (like SSAO or any fast AO) but it doesn't require a Z-buffer, it's quite fast and doesn't depend on the viewpoint.
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« Last Edit: April 17, 2010, 04:29:11 PM by knighty »
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knighty
Fractal Iambus
Posts: 819
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« Reply #13 on: April 17, 2010, 05:53:55 PM » |
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Some results: I used five samples and: k=5.5; delta=0.1 For the mandelbox I had to scale up the DE by a factor of two because the estimated distance is too small in this case.    |
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David Makin
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« Reply #14 on: April 17, 2010, 11:30:29 PM » |
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Now that's cool - it's also similar to an idea I was going to try - namely sampling the smooth iteration *density* at a point or points back along the ray towards the viewpoint and using that to give an AO value, though obviously IQ's method uses the normal as the direction and the DE value/s rather than the smooth iteration density Thinking about it, of course going in the direction of the normal is definitely more correct ! |
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« Last Edit: April 17, 2010, 11:34:16 PM by David Makin »
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January 12, 2010, 09:34:25 PM
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