CompuServe Messages

Lenzfx

    29-Dec-94 22:52:48
Sb: #144035-Lenzfx
Fm: David R. Swoboda 74354,331
To: Aaron W. Ostler 74672,127
Aaron, Sorry if MY message came off sounding harsh, that was not the intent. >>Your discussion of DOF is indeed educational. As per the image in question, a scene very similar to that has already been tested with a real 35mm camera, and the results were exactly the same as in the sample image. So, I guess I just really don't see your point. Or why you persist in the fact that it isn't correct. If you, or anyone who you are willing to quote, is actually saying that a camera, or even our eyes are capable of instantaneously measuring the complete DISTANCE traveled by a ray of light to infinity, you are wrong. If we had this technology, can you imagine the military and scientific benefits alone! Instead, like I pointed out earlier, and even as Kris Malkiewicz writes in the article you quote, perceived focus is dependant on the intensity and angle of light rays entering the lens of the camera or our eye, and how the lens refracts them. << My point, which I evidently did not convey all that well, is simply this: I propossed an assumption that the DIGITAL CAMERA of a graphics program like 3DS emulates a lens system simular to a normal camera. This camera is in turn emulating our vision as seen from our eyes. Following this assumption then the DIGITAL CAMERA would need to follow the rules of a known optics system, the camera, and if it didn't we would PERCIEVE a difference because of our familularity and exposure to said systems every day. I noticed in the thread that no one talked of a real optics system and DOF and it's connection to FOCAL LENGHT, LIGHT, DISTANCE, and APERTURE (F-stop). Not being an expert in optics I qouted a known source so that my ground work would be correct to the best of my knowledge. Several of the statments in the thread were off-the-cuff, or appeared to be and were also wrong. Some worked in a FIXED focal length, FIXED aperture lens system. 3DS is NOT a fixed focal length lens system. Therefore, any real DOF system would need to consider idea's like Circle of Confusion, Hyperfocal Distance, and Near/Far lens focus and Focus Point. In a software emulation I feel you would have to create these known factors in the system for it to emulate a real scnario. In fact, you should be able to go to a DOF chart for your lens focal length and use the figures in that chart to actually place objects an proper distances from the camera for your setup, if you wanted. In Lightwave you CAN actually do this very thing. Making this hypothetical situation, I was hoping you would go into detail on just how LenZFX use these ideas, if it even does. Either I was so UNCLEAR in my intentions that you missed that or you did not wish to discuss those factors. I still agree with Scott that the reflection is not correct. It APPEARS that the reflection of wall would be out of the DOF for that setup and hence be blurred. This is of course based on the output image as I can not look at the setup. << LightWave does have a nice DOF, but its largely unusable because of the time it takes to render. Imagine rendering a ray-traced scene 16 or even 8 times for a single image! >> I use it all the time so I would not say it is unusable. In fact my Company Logo used DOF on a moving camera and turned out very nice. Computers always get faster and faster and we just buy more and more to do our work. It's all part of business. If you want it, you just got to fork out the CASH and go for it. A recent article in LIGHTWAVE PRO by Grant Boucher of Amblin Imaging gave first time testing of LW on a DEC Alpha in WinNT. Surprisingly, on the Alpha, ray tracing was FASTER than non-ray tracing on the same machine! In fact a scene on a stock 040/28 took 4944secs and on the Alpha took only 353secs. That's a factor of 14x faster. Speed is no longer a big problem. If you want it or need it, you can buy it. The MIPS R4400 took 1594secs, MIPS R4600 took 846secs. A Pentium 90 should be about same as MIPS R4400 but was not yet tested. Imagine 3DS on the Alpha/WinNT!!!!!!!! Boy would that ROCK! <<Do you use Lightwave regularly? I do, as well as 3DS and others.>> <<<David, if you want to get into some sort of battle of who has the better toys, you're talking to the wrong guy. Cuz I just really don't care. It doesn't matter what you've got, but how you use it 🙂 >>> Sorry, this is badly phrased. Keep in mind my good buddy is in town form USC Grad FILM program and we have been playing DOOMII networked til about 5am nightly. Should read: I use Lightwave AND 3DS so I feel qualified to speak well on both platforms. I just wanted to point out that some of what you said about LW was incorrect. I really don't care which programe works better, as long as they BOTH do what I NEED. <<Now take this whole message with a small grain of salt (and maybe a shot of vinegar) because there's really nothing in this whole thread that's all that personal. Aaron >> Your right. However, I still stand on my comments concerning your Crayola comment. I do not see your "theoretical metaphor" and think it was off base. Are we having fun yet!? Zippy. DrS