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Author Topic: A different style of reflection  (Read 2342 times)
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DarkBeam
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« on: June 21, 2012, 01:06:07 PM »

I know, this is an hard thing to do, and it's really too much to ask such things for a lovely free software... embarrass

There are different reflection styles, the one built in MB is specular and smooth, but also exists a "fuzzy" one - see this image

http://fractalyst.deviantart.com/art/Ornamental-Orb-287200951

The material on the back reflects smoothly near objects and blurs nicely faraway ones. Probably too hard to do... undecided but lovely effect

Also I noticed that hard shadows always have "hard edges", a softening would be also nice like this



And no there is no hurry to do this - and feel free to send me to hell for asking embarrass

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taurus
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« Reply #1 on: June 21, 2012, 02:13:05 PM »

as you know, i'm no programmer, but i have some expierience with several 3d rendering engines (cinema 4d, pov and some low level renderers built in cad software).
i am courious, if this is possible in a program, that does not provide a real 3d mesh for rendering.
the shadows in your image sample are not only softened (which should be easy), they are area shadows. the ammount of blur is related to the distance between shadow caster and shadow reciever (easy to see when you follow the shadow of the pillar in the middle of the room).
in 3d mesh renderer it increases rendering time moderate, according to the precision used. the softening reflection is also related to distances, so should be similar.

the other effect in your sample - radiosity - is far more expensive. afaik there are several methods of creating radiosity (sample rays, stochastic modes etc.), but in all cases it increases the rendering time dramatically. i guess this won't be very different in 3d fractal renderers, if possible at all.

when someone manages to implement those features, i'll be the first to be thankful trying the possibilities - even if it takes weeks to finish a rendering A Beer Cup
after area shadows and radiosity, there's not much left to create ultra realistic images. maybe lighting with hdri maps... (just a joke)
« Last Edit: June 21, 2012, 02:21:55 PM by taurus66 » Logged

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knighty
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« Reply #2 on: June 21, 2012, 02:50:42 PM »

maybe lighting with hdri maps... (just a joke)
If I'm not mistaken, syntopia is already working on it.
regarding global illumination, lycium did an hyper super realistic rendering of power 2 mandelbulb.
I also remember a wonderful mandelbox render by Hamilton.
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Syntopia
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« Reply #3 on: June 21, 2012, 03:36:43 PM »

Yes, Fragmentarium (in recent GitHub versions) supports both soft shadows via (circular) area lights, and Image Based Lighting using HDRi's (using panoramic .hdr RGBE images for specular, diffuse, and background). There is also simulated Depth-of-field and HDR tone mapping.

For some test renders see, e.g.:
http://www.flickr.com/photos/syntopia/7270132662/in/photostream
http://www.flickr.com/photos/syntopia/7376230282/in/photostream/
http://www.flickr.com/photos/syntopia/6919800648/in/photostream

Wrt speed: Image Based lighting is fast and doesn't slow rendering much (well, not unless you want to calculate shadows based on the HDRi images, in which case rendering will be *much* slower).

Soft shadows and (simulated) Depth-of-field on the other hand requires many samples for each pixel. As rendering time is proportional to the number of samples, this means an image might be 100x slower to calculate (which still might be only a few seconds for simple geometry such as the knot).

It is true that the color bleeding (e.g. red shadows on the white column) on DarkBeams images requires multiple bounces - which again increases rendering times. I plan to do a path tracer implementation at some point, which will allow this - not sure much is gained when working with something with such complicated geometry as fractals, though.


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DarkBeam
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« Reply #4 on: June 21, 2012, 04:24:16 PM »

I know it is different, anyway when I render with reflects putting a dark reflective colour some "color bleed" appears, making very nice effects... Don't know if it's the same I guess no? smiley Anyway just a bit of blurring of shadows would be more than enough, I never use hard shadows btw grin
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taurus
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« Reply #5 on: June 21, 2012, 04:48:17 PM »

Wrt speed: Image Based lighting is fast and doesn't slow rendering much (well, not unless you want to calculate shadows based on the HDRi images, in which case rendering will be *much* slower).
<snip>
It is true that the color bleeding (e.g. red shadows on the white column) on DarkBeams images requires multiple bounces - which again increases rendering times.

it's not only the shadows, that make the difference in radiosity, it's also the color interaction between close surfaces. hdr shadows are already simulated in ambient occlusion and - depending on the scene - not so bad. but the "color bleeding" is something different...
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Syntopia
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« Reply #6 on: June 21, 2012, 05:36:44 PM »

it's not only the shadows, that make the difference in radiosity, it's also the color interaction between close surfaces. hdr shadows are already simulated in ambient occlusion and - depending on the scene - not so bad. but the "color bleeding" is something different...
<Quoted Image Removed>

I know, but this kind of color interaction can be simulated quite easily with path tracing (for a nice WebGL demo see here: http://madebyevan.com/webgl-path-tracing/) - radiosity is just another way of doing it.

I'm not sure I understand you with the shadows: ambient occlusion is different from soft shadows - AO is not dependent on the position of the light sources and will not be directional. It is also possible to estimate shadows based on light distributions from HDRi maps, but this is computationally demanding.

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taurus
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« Reply #7 on: June 21, 2012, 06:58:51 PM »

...
I'm not sure I understand you with the shadows: ambient occlusion is different from soft shadows - AO is not dependent on the position of the light sources and will not be directional. It is also possible to estimate shadows based on light distributions from HDRi maps, but this is computationally demanding.

i think you understood,what i mean. sure, ao is not sufficient to simulate hard contrast maps, but a sky for example with relative constant light is well represented with ambient occlusion - the sunlight is not. but sunlight is also not well represented with global illumination, as the sun normally casts hard shadows.

fantastic realtime demo. i see, that i'm not up to date in those things. my (a bit aged) vesion of cinema 4d needs minutes to produce similar results.
i thought gpgpu is the future, but it's present time too  wink
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DarkBeam
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Fragments of the fractal -like the tip of it


« Reply #8 on: June 21, 2012, 07:25:22 PM »

I know, but this kind of color interaction can be simulated quite easily with path tracing (for a nice WebGL demo see here: http://madebyevan.com/webgl-path-tracing/) - radiosity is just another way of doing it.

I'm not sure I understand you with the shadows: ambient occlusion is different from soft shadows - AO is not dependent on the position of the light sources and will not be directional. It is also possible to estimate shadows based on light distributions from HDRi maps, but this is computationally demanding.



Very interesting! So the fuzzy mirror is called "glossy" wink
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Syntopia
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« Reply #9 on: June 22, 2012, 01:10:38 PM »

Btw, shooting hundreds of rays per pixel is probably not a good idea for M3D (where this feature request was posted).

But the color bouncing/bleeding effects can be simulated in screen space in a way similar to SSAO - this is called SSDO:

http://www.geeks3d.com/20100619/ssdo-screen-space-directional-occlusion/
http://cg.alexandra.dk/tag/ssdo/ (sorry, in danish)

I'm not sure it adds much to the realism, but at least it is fast to compute :-)

« Last Edit: June 22, 2012, 01:12:21 PM by Syntopia » Logged
DarkBeam
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Fragments of the fractal -like the tip of it


« Reply #10 on: June 22, 2012, 04:16:38 PM »

Looks like an awesome idea, thanks! A Beer Cup A Beer Cup A Beer Cup
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DarkBeam
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Fragments of the fractal -like the tip of it


« Reply #11 on: June 26, 2012, 08:49:26 PM »

In the meantime I made a room Difs formula with differently colored walls... grin


Mandelbulb3Dv17{
Z.....x/...r3.../....2....URw8.Q.xCpzqSzkBKh6./Eus1dtEUAIz9qX0XQDgmgysrUO8uaqRsD
................................UcA7IS5db.2........A./..................S/2...wD
.........cks/.../M.0/.....UF0...8.....E4.....M1iZvSkeSlD/......./K3o0dkpXm1.QJJV
./EnAnQD12..2..dDIRZanH1.lhoC1mtCxzjx7yQCif9K.A............u1....y1...sD...../..
.z1...sDV.lKPUB1YwnayWlLcAbMyqAp2k5p3Onj2dfAa1qWEqHTSr/foQ8CzqLjjMw6mEaD6M5uxFRV
qwfCoXHF3r4Iy0uGga/qAEmj......IX..............kD.I....sD..E.0...................
.............oAnAt1...sD....zUmbo9.mTGj.c/8x0UEco9.eVGj.678x0Uico9....../....k1.
..................kz.wzzz1.U..6......M4...EB....W..........F....8/...I1.....SN52
...U.qFG9yzb2zzzRYoWzz7lz16/4IZzzzzz..EzRQrzS4uD3Yl1z/xv9z9.s6ZeQQLlz2.28.kFrA0.
.Ub96aAIVz9.1se7Umvxz0........../EU0.wzzz1...........s/........./.........E.2c..
zzzz.............0...................2./8.kzzzD.................................
/EU0.wzzz1...................................wzzz1kzzzjvz10U.06.zzzzS9R7z1...wzz
zTi0g.6U.0kzzzjvxy1U.06.zzzzi1.I.06U.wzzzviHF/6U.0kzzzjvvJ3U.06.zzzzi5wJ.06U.wzz
zvCmw/.U..kzzzjv..EsUa3.eeWCNq0.IJ36wk8.wyLsUa3.................................
E....2....E.....I....o....UQjxKPXlaQ7NoI.A5...........................U1C....6..
..........UaNaNaNaNiz..........E................................OaNaNaNaty1.....
..............zD........kz1........wz..........E...................wz...........
........................}


* italia_room.jpg (34.56 KB, 1000x750 - viewed 227 times.)
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Jesse
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« Reply #12 on: June 26, 2012, 10:15:52 PM »

Maybe you noticed that i already did some monte carlo simulated renderings in a hidden function in m3d because of lack of user interface and like Syntopia mentioned, the long render times.
So this image took 25 minutes on my older laptop, whereas the usual rendering would take 5 to 25 seconds dependend on the calculated options.
(I sell the activation procedure of the mc easter egg in m3d for the most bidding one wink )



* italian room.jpg (87.7 KB, 800x600 - viewed 220 times.)
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DarkBeam
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« Reply #13 on: June 27, 2012, 09:37:12 AM »

The color diffusion looks very subtle btw wink I don't notice a diffusion of the green?

And, what if you realize a "stoppable" rendering? I mean, that you can halt anytime like in the realtime script wink
« Last Edit: June 27, 2012, 09:58:01 AM by DarkBeam » Logged

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taurus
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« Reply #14 on: June 27, 2012, 10:18:46 AM »


... and like Syntopia mentioned, the long render times.


considered trying this ssdo procedure?
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