Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!hellgate.utah.edu!helios.ee.lbl.gov!nosc!crash!pro-graphics.cts.com!bobl From: bobl@pro-graphics.cts.com (Bob Lindabury) Newsgroups: comp.sys.amiga Subject: Re: Frame Buffers Message-ID: <1746@crash.cts.com> Date: 6 Mar 90 08:56:11 GMT Sender: root@crash.cts.com Lines: 92 In-Reply-To: message from wayneck@tekig5.PEN.TEK.COM > In article <1689@crash.cts.com>, bobl@pro-graphics.cts.com (Bob Lindabury) writes: >> Seems the boys at Byte by Byte could care less about us Amiga users because >> they are going after the Mac carrot (or is that Apple?). At any rate, it >> seems that not much forethought was put into the Sculpt product and they opted >> to optimize the redering routines for the Amiga's display modes and didn't >> even consider 24 bit rendering to any large degree. Seems the software will >> produce these bands so that another routine can dither between them to get >> those nice HAM images. Too bad that the bands are not skipped when rendering >> in 24 bit mode. So, an otherwise perfectly good product is "rendered" next to >> useless for 24 bit images. Yeah, doesn't everyone want to drop $500 for a 3d >> ray tracer that doesn't do 24 bit well? How about we all drop our bucks on >> the product so that Byte by Byte can do more Mac developement? These ideas >> dosn't sound good to you? Hmm... > > The problem isn't rendering to 24 bits. It sounds like that works just fine. > Once you have 24 bits per pixel rendered and displayed it isn't possible to > dither anymore. What data can be used to control the dithering? One could > take the 24 bit image and dither it to say an 18 bit images (6 bits per red, > green, blue). This would reduce the number of colors in the image and reduce > the resolution to a lesser degree. It would be similar to running the image > though a low-pass filter. Anyway the picture would become kind of HAMish, that > is it would appear softer. If you want to dither to 24 bits, you have render > something like 30 bits per pixel or 36 bits per pixel would be even better. > Then you have some data to dither on. Wayne, it seems you've missed my point. If you (or Byte by Byte) were rendering TRUE 24 bit images, they would have no need to do ANY dithering at all! I don't want my 24 bit images dithered!! Sculpt does NOT render 24 bits well and that is the whole point. They go through a PRE-dithering sequence even when doing 24 bit images. This in not require, needed or even wanted. It is unacceptable. >> I'm still waiting for a "good" 3D program with an interface like Caligary, >> Editing easy like Sculpt and rendering/mapping capabilities like Turbo Silver. >> If all the best of each of these programs were incorporated into a new 3d >> program that also supported the Renderman Spec, I would (as others would) jump >> on it in a second even if it did cost in the $1000-$2000 range. > > I think you realize what Renderman is all about. Anyway if you what to use it > be prepared to pay a lot. The main feature the Pixar uses is called 'shaders'. > Only there is a problem --- 'shaders' are not a part of the Renderman Spec.. > This means if you want those Pixar quality pictures you better buy Pixar's > Renderman Render. Also shaders are pieces of code so if you aren't hot at > physics and programming you end up paying a lot to get them written. (Pixar > has to make money after all.) However, the end product can be amazing. The > sharders can turn a run of the mill image into a near photo-realistic image. > What will this cost? Well the Pixar Renderman render sells for $4650, plus > you need a Mac II or PC with a transputer board if you want images in less > than an hour. You are looking a $10,000 to $15,000. Still hot on Renderman? You miss the point here again Wayne. Obviously I don't want to do Renderman rendering on my Amiga...that is not the purpose for which I intended the Renderman spec be used. What I WOULD expect is that the higher priced 3D programs support the output of Renderman definition files (or whatever they call them) so that the final output could be rendered on a Pixar engine or some other machine that is JUST a renderer. Hey, who expects to render these type of things on the Amiga anyway? You? Certainly not me! If I had my druthers, I would like to do quick pencil test type rendering on the Amiga to make sure that the movement and such were fine..I would also probably render at least a few key frames to make sure lighting was good. This could be done in either Ham or maybe some other appropriate mode on the Amiga (preferably 8 bit if we ever get an 8bit card) that would be relatively quick and still give us a good indication of the "look" of our scenes. From there it would be rendered frame by frame to either video or film on a Pixar or some other such rendering engine. Of course this is going to cost some money. Those willint to pay will do it because most of the cost is in the creation..not the rendering. >> You mention nice dithering in Turbo for 24 bit images. I'm not sure what you >> mean by that but with a 24 bit image (over 16 million colors available) you do >> not need to do any dithering. > > This is simply not true. It is very possible for 24 bit images to have > banding. Isn`t that what you were complaining about at the biginning of > this article. > Wayne Knapp Again, you are not reading my message correctly. Refer to my first paragraph on the problems with dithering and 24 bit images. We are NOT coming from 32 bit images. We are generating 24 bit images from scratch..dithering shouldn't be done as can be evidenced by the horrible output from the Sculpt program. -- Bob _______________________ Pro-Graphics BBS 201/469-0049 ________________________ InterNet: bobl@pro-graphics.cts.com | ProLine: bobl@pro-graphics UUCP: ..crash!pro-graphics!bobl | CServe: 70347,2344 ARPA/DDN: ..crash!pro-graphics!bobl@nosc.mil | Amer. Online: Graphics3D ___________ ____________ Raven Enterprises - 25 Raven Ave. Piscataway, NJ 08854