| Author | Message | ||
     Anonymous Rating: N/A |
Hi! I'm trying to setup camera sttings for a 3D-Animation that is going to be displayed on a 5 meter wide screen. Two projectors is going to be used, the 3d stereo effects is going to be created with polarazed light. I need to find out what settings to use for the eye separation, and so on... Anyone know where I kind info on how to calculate the settings...?? I've found some plugins for 3DSMAX, but none of them seems to give me the info I need... // A | ||
| Puppet Kite Kid Rating: N/A |
This is a very complex issue, and it seems that I find myself neck-deep in debates about this every other month or two over in the Yahoo Photo3D group... so even the projection experts (and I'm surely not one :-) tend to have varying opinions. Basically, there is actual stereo base (separation of the cameras) to deal with, along with on-screen image separation, and those are two different challenges. The basic *rule* that seems to be challenged the most is "the eyes should never diverge". The problem with that rule is it's extremely hard to implement, especially when screen sizes get *large*. So, if I could sum it up in a paragraph or two, I surely would, but you should be able to see that this is a mathematical nightmare. At some point, most people just "toss in the towel" and stick to typical stereo base *rules* (even that is highly debated, though), and put up with whatever happens on the bigger screens. Just to give you an example, with stereo movie stereo base, I usually try not to exceed the 1/30th rule (the cameras are separated 1/30th of the distance to the nearest object in the scene), but with CGI (or in my case, "computer-manipulated imagery"), I am "all over the place" with the total deviation, so at some point you have to try to learn what to look for, or precisely, _check your work_ before you actually render the final edit, which isn't always an easy thing to do :-) Sorry I am so vague, but this is not an easy issue! Usually, a bigger screen simply means bigger challenges. As far as stereo base and deviation is concerned, many times "less is better" for these reasons, but you then stand the chance of reducing your overall stereo effect to the point that it just isn't "good enough"... yes, this can be a catch-22 :-) P. K. Kid Non-commercial stereoscopic 3D video: (All G-Rated) http://www.puppetkites.net | ||
| Anonymous Rating: N/A |
Thanx for the input! I still don't know what settings to use though... I know the size of the screen and the viewers distance to the screen it self. I've also read that you shouldn't have more then 65 mm of eye separation... but that is in relation to what?! How do you avoid getting the eyes diverged? is that when the focus point(target) is infront of the object? I also understand that you can't have "too" big separation, since it would look out of proportion on a big screen... So should I go for the 1/30th rule? nad where should I put the target point? Does anyone know where to find thoose mathematical terms to use? // A | ||
| Puppet Kite Kid Rating: N/A |
As I said, this is a mathematical nightmare. You can make all sorts of rules, but very few people will stick to them :-) Our eyes are approximately 65mm apart, so this is sometimes a recommended stereo base for "typical shots", as long as the nearest object is farther away than 6 feet (or whatever 65mm x 30 is, if you want to be exact). This is where "staying within the limits of the 1/30th rule" comes into play, as far as "typical shots" go, but once you go beyond 150 feet (or so), you don't see any 3D effect, except for how things farther away than that "compare" to closer objects, which actually are _outside_ the scene (peripheral vision, basically). At this point, you have an option of spreading apart your cameras and widening your stereo base to create a 3D effect... So, to put this all into an _example_ of practical use, in scenes that include a "near point" of between 6 and 150 feet, I usually choose to use an "orthoscopic" stereo base of 65mm, to make them appear "natural". Scenes with objects closer than that need other techniques to avoid excessive deviation, usually involving reducing the stereo base to less than 65mm to the limit of the lenses (not a problem with CGI :-), and/or using a tad bit of toe-in (bad, bad, bad ;-), and/or avoiding a distant background (or blurring it out). In scenes that include _no_ near point closer than 150 feet (or so... actually, usually less), I usually widen the stereo base to something near 1/30th of the distance to that "near point" (i.e., using the "1/30th rule"). Those are my basic rules... and those are the ones that I usually choose to break for all sorts of reasons :-) Now, on-screen deviation is another nightmare... Even using my stereo base "rules", with a large enough screen, you can end up having to set everything on screen to in front of the stereo window, to avoid eye divergence in distant objects. Most people are not happy with that arrangement :-) Your screen may not be large enough to cause problems. Now here's where my projection knowledge suffers... I'm not sure how to do the math, but you should be able to somehow measure the percentage of image separation in your imagery (one that shows the maximum amount of deviation that you used, in combination with a *reasonable* stereo window alignment) and scale it up to your actual screen size to come up with real numbers. Any image separation more than 65mm will cause people to diverge their eyes... and 65mm is _not_ very far on a big screen. (Some people claim that a small percentage of eye divergence is "acceptable", but tell your eye doctor about that and see what they say! ;-) ;-) ;-) My opinion is that a few inches *might* be okay, but a few feet???... well, you get the picture ;-) PKK | ||
| M.H. Rating: N/A |
You must put in your calulation the epxpected user distance from the screen ! Human eye can diverge about 1.5 deg. Projection use usualy the human max divergence + convergence as well ... Just calculate how big is the distance of 2 points on your screen when seen at 1.5 deg from the expected distance + make your scene in a way that after zooming on the screen you will not exceed this nuber for out of screen effect (you can exceed it a bit for in screen effect) ... | ||
| Puppet Kite Kid Rating: N/A |
Here's the movie segment I just finished this morning. On a 15 foot wide screen, the distant image separation is right at 2.25 inches... so I haven't figured the "1.5 degree" factor that Michal suggests, but any screen wider than 15 feet would cause some eye divergence. This is just an example. For obvious reasons, I really would not prefer to change the on-screen alignment, so I assume at some point, eye divergence would be unavoidable. Just to demonstrate the many challenges you can face, the stereo base varied from about 10 feet down to ortho, and I didn't measure the total deviation, but I tried to keep it to a minimum (whatever that is ;-). Mt. Rainier, the Fremont Firetower above Sunrise and a snippet of "Facing Reality", a 1050's educational movie, all separately layered and animated: http://www.puppetkites.net What's the "purpose" of this movie segment?... Well, my wife laughed when see watched it, and IMO, that is one good purpose :-) The stereo window was animated here, too, and set to "minimize" ghosting. It became a serious challenge because there were two high-contrast areas in different depths of the scene... the snow on the mountain and the cables in front of the firetower window. I think I got the job done. I also used a blurred border for both the parallel and anaglyph versions in this one, to "reduce the effect of window violations". PKK |
