Basic CGI 3D questions

[Philip Powell]

I know this area is dedicated to mostly actual "real life" rigs for 3D, but thought it couldn't hurt to ask.

But I've been eager to experiment with some 3D created from CGI and am still confused by a few basic points after my reading.

Are CGI camera rigs usually parallel, or "toe in"?

How in the CGI domain do I go about calculating where positive, negative and zero parallax are?

I have plenty more questions but that's my starting point. Oh, and if anyone can direct me to some good CGI stereoscopic links that would be great.

Thanks for sharing.

 

[Markus Lanxinger]

http://www.digitaltutors.com/store/product.php?productid=3611

check this one if you know Autodesk Maya.

best
markus

 

[Philip Powell]

http://www.digitaltutors.com/store/product.php?productid=3611

check this one if you know Autodesk Maya.

best
markus

Thanks. I'll buy that, it should be helpful. It's odd there's tons of information I can find on shooting "live" 3D, but very little on the do's and don'ts of CGI.

I'm going to be working in Lightwave, but hopefully the content will translate.

If anybody else has information or links, please send them my way.

 

[Rich lee]

Here is all i got...some of the details are foggy...Years ago a company i worked at did some work on Cameron's 3d titanic project. A lot of the same rules apply from real life cameras to stereoscopic 3d cameras.

The good thing about stereoscopic in 3d is that it is incredibly easy to experiment...much easier then with real cameras...so if you are looking to see if something works or not...just try it. Try it on simple light weight scenes and render in open GL so you can pump stuff out faster...the only thing you will have to bump up is the anti-aliasing because it can get distracting in 3d.

A simple rig we had setup was like this.

(we always worked in real life scales, 1 unit was an inch (sometimes a foot if the scene is huge) and the entire scene was based on that...everything was scaled and sized correctly.)

2 cameras separated by a couple inches pointed/constrained/fixed to the same interest/null object/point in space...moving the null along the Z axis to line it up with the object you want to focus on.

I think we did parallel cameras as well...but honestly cant remember.

Render the two cameras and combine in AE using the stereo plugin to view...or you can render the two images and still run through AE but put them side by side and cross your eyes to view.

 

[Gavin Greenwalt]

Here is an excellent article for you to read:
http://features.cgsociety.org/story_custom.php?story_id=4985

Toe In or No?
Apparently Dreamworks doesn't.

 

[Philip Powell]

Interesting

Interesting

Here is an excellent article for you to read:
http://features.cgsociety.org/story_custom.php?story_id=4985

Toe In or No?
Apparently Dreamworks doesn't.

So, then everything would be in -Z space correct, if you shot parallel and not toe-in correct?

Would that even be true of objects that were at infinity? Would objects at infinity simply rest on the screen plane?

How common is it in CGI land for studios to increase the interoccular distance between cameras to create a "bigger" effect? If so, what's a common distance that folks often "bump it up to?"

Thanks everyone for your insights.

 

[carlo macchiavello]

hi Phil,
i use lw and recently i did many thing in stereo,
first, don't use anagliph system of after effects, it's terrible, adobe don't know what mean anagliph or 3D...
there are many way to build it, you can find below some link to see how to compose a good optimized anagliph which help you to see the depth.

3dtv.at - Anaglyph Methods Comparison
Anaglyph Color Correction in After Effects

second, buy a good glass to see anagliph, i bought on ebay this
http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=250375302267

them have a good dioptric correction, that help you to see in the right way the anaglyph.
if you need some info or other, let me know, i'm happy to help you.

 

[Philip Powell]

hi Phil,
i use lw and recently i did many thing in stereo,
first, don't use anagliph system of after effects, it's terrible, adobe don't know what mean anagliph or 3D...
there are many way to build it, you can find below some link to see how to compose a good optimized anagliph which help you to see the depth.

3dtv.at - Anaglyph Methods Comparison
Anaglyph Color Correction in After Effects

second, buy a good glass to see anagliph, i bought on ebay this
http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=250375302267

them have a good dioptric correction, that help you to see in the right way the anaglyph.
if you need some info or other, let me know, i'm happy to help you.

Just PMed you Pixel...thanks,

 

[anzyyy]

hey this thread is really very informative..... :attention9ha:

 

[Philip Powell]

interocular distance

interocular distance

Something I've been struggling with is how do you set up scale using your basic interocular distance with of 2.5 inches in a scene with "Non-real world objects" or microscopic objects for instance?

If I wanted to view microsopic objects for instance, it seems like I would need to multiply down my interocular distance? Am I thinking of this correctly?


Also, I'm wondering how often the big boys CGI use rigs that are hyper stereoscopic? I read in some paper that Beowolf used this technique some. If so, how much do they push the distance?

sorry for the CGI questions in this basically Camera thread...if it's bothersome to some please move it. Thanks all for you time.

 

[carlo macchiavello]

3d world allow you to do something that you cannot do in real life, for example you can change the size of objects, you can shoot different plane and composite perfectly later, and more...

from my small experience with 3d and stereoscopic :
- don't change size of obj, or you risk giant effects when they came out of screen, or a gnomon effects when they run in the screen to much fast
- don't use different rig to build different plane, that causes some headheache when eyes try to focus something that they can't.
- don't use fish eyes, use normal lens
- try with anaglyph, it's a good replace to test images for the big screen, common active glass, or other way are not enought good to simulate the different depth that you have on big screen.
if you do object that come out of screen a lot on your small screen, on big screen will be overlapped, eyes can't focus on it
if you do objects that come out correctly for big screen, ofnel on small screen (under 40') is not enought strong the effects, and you are tempted to force the depth, if you use anaglyph, which is a bit stronger than many different way to see 3d, you can have a good effects like to cinema on small screen (24, 26') and you can calibrate it correctly.