Faking it.........

[s o u t h e r n]

Faking Radiosity in ZB. Well, almost..

http://www2.zbrushcentral.com/zbc_uploads/user_image-1001983532onc.jpg

I have had limited exposure to applications that use radiosity (ETShadePro R4 being the most recent). My understanding of it is that it is a set of alogythingysrythyees that bounce even more light rays around than normal raytracing. Given that in the real world (A place I visit Ohhhh so infrequently these days) light bounces around all over the place and carries with it the colours of the objects it touches...so..in these images.. the lighting on the walls matches the lighting on the jars..blue to blue, orange to orange. All done with glows.

http://www2.zbrushcentral.com/zbc_uploads/user_image-1001983762lpc.jpg

It would be really cool if someone who actually knew what they were talking about here jumped in and told us all what radiosity is really about coz I made all the first bit up ;)

http://www2.zbrushcentral.com/zbc_uploads/user_image-1001983847xoo.jpg

Some weird shadow effects started to appear on these images. Not really to sure how I did it :)

http://www2.zbrushcentral.com/zbc_uploads/user_image-1001983897ost.jpg

http://www2.zbrushcentral.com/zbc_uploads/user_image-1001983935kih.jpg


Have fun.

G

[aurick]

I got so caught up enjoying your lighting effects that I almost missed the fact that you've used the same texture for every item in the image. Good job, hiding that.

I can't really add to the thread, since lighting is still a bit of a mystery to me. So all I can say is... awesome! I'll have to try that glow effect, myself. Thanks for the inspiration!

[Kruzr]

'Evening gentlemen . . . :)

Maybe this will help some in the understanding of "Radiosity". ;)


Radiosity is an addition to typical 3d rendering methods that increases the realism of any given image by a multitude. The theory behind it is that light does not just bounce off of objects and go into a persons eye, it also bounces off of objects onto other objects and then into the persons eye. And it also bounces off of objects onto objects onto yet more objects and then into the persons eye. And you can trace that until certain rays of light have bounced off of every single object in the room before it even reaches the eye. And that is actually what happens in real life! It results in something that one might refer to as "color bleeding".

For an example of this, you could take a tennis ball, and hold it about a half inch away from a piece of white paper. If you look closely, the part of the paper that the ball is closest to, has become a slight tint of yellow. That is the phenomenon of radiosity at work.

Probably the most interesting thing about radiosity is that the human eye is very sensitive to it. If radiosity is not present in an image (such as with a typical 3d rendered image) your brain will flash a "not real" warning flag. That is why you can often tell that computer images are... well, computer images. You can tell that they are not real.

But many 3d rendering programs now have an option for rendering with radiosity. Lightflow, ( http://www.lightflowtech.com ), for instance, has radiosity as a standard feature. In fact, it was designed around radiosity in the first place. Also, all composite computer graphics that you see in movies are typically rendered with radiosity. Maya, for instance--which is a 3d graphics program used in many movies--can render with radiosity.

So how do you calculate radiosity? Well, it is a theoretically simple method, but that when put into practice is extremely complex and often unreasonably slow. Of course, there is more then one method, but I am speaking of the traditional method. What you do is you first calculate lighting a single time, in the normal way, except you store the light values of any given polygon (i.e., how much light is reflecting off of it) as opposed to merely the color of the polygon after the lighting has been completed. Then, you use a recursive subdivision technic to subdivide the meshes wherever there is an inconsistency across it. You then recalculate the lighting for the scene, storing the lighting values again. Except this time around you also take into account the light that is being reflected off of each of the polygons, and treat each of those as if they were a light source them selves. Also, you now have more polygons to calculate light values for because you subdivided them. You continue to do this until a user set thresh-hold, and then you stop. You now have thousands and thousands of polygons which all have their own light values, with radiosity taken into account. You then render the scene using interpolation across the surfaces of all polygons.

I hope this brief summary will help everyone to understand the theory behind "Radiosity" in 3D rendering a little better. :rolleyes:

Have a good one . . . :cool: Mark.

[s o u t h e r n]

Wow..Kruzr, I`m green with envy at your knowledge of the subject.

http://www2.zbrushcentral.com/zbc_uploads/user_image-1002010453tpf.jpg

Thanks for that. Do you use any of the high end applications like Maya?

[Kathy]

NV - *snicker* that's great :D .......


Damn Mark, that last paragraph reminded me of college. STOP IT. :p

Radiosity; What Kruzr said. (you da MAN mark, well except when you are wearing those manties..... ;) :p :D ) HAHAHA!

Radiosity according to me; creating real life prism color changes and refraction by algorythmically applying color reduction on the hue level with converse shadow algorythms applied on the saturation level.

True dat. WORD. :cool:

[Kruzr]

Morning Glen . . . :)

The above post is not completely in my own words. There is much that is from several documents that I have download in the past. ;)

I used to do a lot of beta testing for 3D software developers when I was on the Amiga platform several years ago. It was during this time, that I started learning about "Radiosity, Caustics etc.". I used to continually ask questions regarding this topic, to the developers & in return they told me to start doing some research on the subject, so I didn't have to ask so many questions. It was then that I started reading & downloading as much information as possible on the subject. I can't remember where the above basic information came from or even who it was written by, so I can't take all the credit for the wording. :(

I used to have a good friend who worked for a professional graphics company, in the Silicon Valley. He would invite me over for the day, several times, & I would drool over all the $ 100,000.00's worth of high-end computers & 3D software. Sometimes I would even get the chance to use these computers - AMAZING! - then I would return home & sit motionless in front of my lowly Amiga. :)

Anyway, that's pretty much it. As far as my owning or using any high-end software now, the answer to that is no. It's too expensive to purchase, then continually upgrade the software, just to keep up with the times & technology of the same software. Besides, the work I do now doesn't justify the cost of such software. There is software out there today that will do exactly what is being discussed here today, & it will run on today's home computers, but, the time it would take to render even on the fastest home computer would be ridiculous. You would have to have a half dozen systems or more to be able to use that type of software with any productivity. I do have one friend that still uses high-end graphics software at home, but he has a render farm consisting of about 8 or 10 computers. :(

Hey Kat . . . :D

"you da MAN mark, well except when you are wearing those manties.....", I beg your pardon young lady, I don't wear those things! :( :( :(

I receive an e-mail from ZDNet yesterday, & in it was an article about the 5 worst sites NOT to download anything from & that site was one of them. I figured that some would get a chuckle, after visiting the site. ;)

But I can see that your still going to pick on me - push me around - embarrass me - just totally put me in a state of humiliation so I won't show my face in public any more. I'm glad your married to someone else, you can do all that to him & probably get away with it. But, if you were married to me, you'd be sitting in the closet for at least a week, & during that time, you'd have to write 10,000 times, "I will not be nasty or mean to Good'Ol Mark Again". Then when you were finished with your punishment, I might let you walk along side of me down the street, instead of in back of me. :D :D :D

Anyway, you guys & gals have a good one . . . :cool: Mark.

[Kaz]

Ah yes, the days of the Amiga. Personally, I was on an Atari ST, the Amiga's less functional competition. No HAM mode for me, it maxed out at 512 colors. But that is where I first saw Raytracing...GFA Raytrace.

Anyway, for Radiosity I have used Strata Studio Pro. But only for experimentation. The MacIncrashes could never complete a full render.

Also, I have played with Lightscape. Cool stuff. This would calculate all the lighting once, then allow you to do a walk through in real time. You know these guys are serious when you can set the exact type of light bulb, down to the manufacturer, as well as the geographic loction, season, time, etc... ("What would me office look like at 4:00pm on August 1st if it were in Atlanta?")

I have heard Radiosity compared to Raytracing this way:

Raytracing calculates from the camera view to the light source.

Radiosity calculates from the light source to everywhere.

To see a comparison, check out this link...
Light Scape (http://www3.autodesk.com/adsk/index/0,,776399-123112,00.html)

[WingedOne]

I did something in ZBrush using Faked Radiosity. See my post way below "Faked Radiosity". I had posted it on some weekend evening and it was quickly buried by a gazillion other posts. :(

I like the one that's third from the top. That one looks the most "radiosity-like" to me.

[Kaz]

Here is WingedOne's post:

Faked Radiosity (http://www.pixolator.com/zbc-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=001058)

[AngelTwo-Six]

I wonder if Ultimate works well with the graphics turned off?

I'm never going to learn anything coming here because I start looking at the pictures and then forget to read the text!

a2-6