Forum Moderators: RedPhantom
Poser - OFFICIAL F.A.Q (Last Updated: 2025 Feb 17 1:30 pm)
hi all,
I'm doing stereo every now and then and never had issues. My way of work is:
Works fine.
But still I have questions. I can create depth by increasing the stereo base. I can create depth by applying focal blur / depths of field / using focal distance. i can create depth by using shorter lenses (focal length) instead of long ones. But what are decent mixes?
I never combined a large stereo base with focal blur, but I experienced the MIB3 movie (the cafetaria scenes at the end) doing it. Confusing, unnatural but very effective. I always found combining long lenses with a larger stereo base counterproductive.
What are your opinions and experiences?
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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.
visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though
Sorry, was out of town for a week.
Lesbentley: For the same stereo effect, the stereobase is inversely proportionnal to the focal length. So the stereobase should be decreased when you increase the focal length. The determination of the stereobase is a complex thing and many factors have to take into consideration. This is what the Bercovitz formula is doing. I wrote an interactive python script to found the stereobase of a Poser scene based on the Bercovitz formula. I posted the script in the free stuff section at:
http://www.renderosity.com/mod/freestuff/details.php?item_id=62961
Run this script in Poser 7 or 8. Follow carefully the instructions.
For more about stereobase, see:
http://www.kiwizone.org/stereo/3dtake/fbercowitz.htm#bercovitz
The stereobase should be also modified depending of the viewing condition (stereoscope, computer screen, 3DTV or cinema) because of the viewing distance. The more you are distant from a stereo image, the more you will see the stereoscopic effect. Try it with a red-cyan image on your computer screen.
aRtBee: The Bercovitz formula is your response.
The Bercovitz formula appears in the above image. The factors are:
SB = Stereo Base (distance between the left and right camera optical axes)
ofdd = On film deviation difference
F = Farthest distance from the camera lens
N = Nearest distance from the camera lens
f = Focal length of the lens
a = Distance at which the camera is focused
ofdd determine the stereo effect. ofdd is the difference between the same point in the right and left images when you superpose the image in a red cyan stereoscopic image. As a guide, this distance should be equal to less that 5% of the image wide. The full story is a little be more complex, but I give here a quick response.
Allstereo
Thanks for the formula. On top of that, I was curious for your practise:
do you use focal blur / depth of field when rendering for stereo
do you use long lenses when rendering for stereo
best regards
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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.
visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though
Hello all,
aRtBee: I don't use focal blur / depth of field effect. A personnal choice. You can but sometime, if you want to see the near and far objects and their relationship in the 3D space, it is better to keep far object in focus. This is the beauty of stereoscopy relative to human view system where focus is made on a specific object with some ignorance ? of surrounding objects.
For focal length, in Poser, I used a 55 mm focal length. However, if your viewing distance is more than the real distance between the virtual camera and the object, it is better to use long focal length zooming on the objet with no change in the stereo base. Too complex to explain here the rational.
Allstereo
thanks a lot !!
- - - - -
Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.
visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though
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Here is a new version of the SterioCams. I think it is a big improvement on my first effort. This version uses three cameras Camera_A is the "right eye" and Camera_B is the "left eye". The third cameras is named "Camera_SteroCTRL", all the movement of the cameras, and their settings, are done by manipulating this camera. The other two cameras are locked, and can't be manipulated directly, they are parented to the Camera_SteroCTRL so that they move with it, they inherit the other camera parameters (focal, focal distance, etc) from the Camera_SteroCTRL.