As my training continues I seem to understand less and less...
There is so much in Stereoscopy that seems to be counter intuitive when you have spent the last 20 years working in 2d. So far my position on the interocular is that you should approach each job differently.
I have read conflicting articles and been given conflicting advice, and I realise that the distance between the cameras is critical to the amount of '3dness' on the shot and how much of the shot will be usable or rather 'fuse-able'.
This is my take on I-O or if you prefer I-A so far... I'm not saying it is right - it just what I have learned so far.
Don't Shoot The Messenger.
The average distance between the human eyes is 64mm (2.5 inches for those that still use imperial). If you hold a coffee cup up in front of you at arms length and concentrate on the cup. You can see the front and a little of each side of the cup. If you could have a drink of some magic potion that would make you grow into a giant - say 12 feet tall - double your size in all dimensions you would hold that cup in front of you and be able to see that little bit more around each side of the cup. So if you shoot with your cameras say 130mm (5 inches) apart then you are replicating the view of that 'giant' person. Which means that the cup will look small, half the size. Or put another way, from the perspective of the cameras the cup has shrunk... So when you show these images in 3d the amount of 'depth' in the picture of the cup would indicate to your brain that you have turned into a giant, or more reasonably this is a smaller cup than 'normal' because you can see as much of the cup as you would have, had it been half the size! Stay with me, I did some tests and am happy to email them over... reg@shoot3d.tv. I bought 2 identical cups - one large and one small and took some very accurate still photos (based on the above) and compared the results - then I made 3d photos and showed them to a group of friends - there were no size cues in the pictures - just the stereo photo's of the cups. Without fail I could 'make' the big cup look smaller in 3d by using a larger interocular IO than is natural. So the 'Hyper Stereo' stuff that you may have read or come across is REAL. Then I found out that some of my sample viewers have enhanced 'stereo-acuity' (ability to judge / perceive 'depth' - relative size and geometry - based on interpretation of vertical disparities).
Now - where does this lead me. If you have seen any of the Sky TV 3d coverage of the UK football (Soccer) matches in 3d then those of you with high stereo-acuity may have found the 3dness a bit strange - and giving you the sensation that you were watching 'miniature' sized men running round a field! This is because some of the cameras had quite a large interocular. The view is generally that you can 'get away' with this in sport.
Here's a thought...
If you were shooting a commercial in stereo 3d, you have 2 guys, one with an aftershave product that is supposed to make him more attractive to the girls, then you might make him slightly 'larger' (hypostereo) by moving the cameras closer than the human IO (say by 10mm) and shoot the other guy in your commercial who is the 'loser' wearing the 'nobrand' aftershave - well, you could shoot him with a slightly larger I-O`(hyperstereo), again say 10mm - this might psychologically give an advantage to the 'hero'. I'll try it out and let you know if I get a script in for a 3d commercial.
There is so much in Stereoscopy that seems to be counter intuitive when you have spent the last 20 years working in 2d. So far my position on the interocular is that you should approach each job differently.
I have read conflicting articles and been given conflicting advice, and I realise that the distance between the cameras is critical to the amount of '3dness' on the shot and how much of the shot will be usable or rather 'fuse-able'.
This is my take on I-O or if you prefer I-A so far... I'm not saying it is right - it just what I have learned so far.
Don't Shoot The Messenger.
The average distance between the human eyes is 64mm (2.5 inches for those that still use imperial). If you hold a coffee cup up in front of you at arms length and concentrate on the cup. You can see the front and a little of each side of the cup. If you could have a drink of some magic potion that would make you grow into a giant - say 12 feet tall - double your size in all dimensions you would hold that cup in front of you and be able to see that little bit more around each side of the cup. So if you shoot with your cameras say 130mm (5 inches) apart then you are replicating the view of that 'giant' person. Which means that the cup will look small, half the size. Or put another way, from the perspective of the cameras the cup has shrunk... So when you show these images in 3d the amount of 'depth' in the picture of the cup would indicate to your brain that you have turned into a giant, or more reasonably this is a smaller cup than 'normal' because you can see as much of the cup as you would have, had it been half the size! Stay with me, I did some tests and am happy to email them over... reg@shoot3d.tv. I bought 2 identical cups - one large and one small and took some very accurate still photos (based on the above) and compared the results - then I made 3d photos and showed them to a group of friends - there were no size cues in the pictures - just the stereo photo's of the cups. Without fail I could 'make' the big cup look smaller in 3d by using a larger interocular IO than is natural. So the 'Hyper Stereo' stuff that you may have read or come across is REAL. Then I found out that some of my sample viewers have enhanced 'stereo-acuity' (ability to judge / perceive 'depth' - relative size and geometry - based on interpretation of vertical disparities).
Now - where does this lead me. If you have seen any of the Sky TV 3d coverage of the UK football (Soccer) matches in 3d then those of you with high stereo-acuity may have found the 3dness a bit strange - and giving you the sensation that you were watching 'miniature' sized men running round a field! This is because some of the cameras had quite a large interocular. The view is generally that you can 'get away' with this in sport.
Here's a thought...
If you were shooting a commercial in stereo 3d, you have 2 guys, one with an aftershave product that is supposed to make him more attractive to the girls, then you might make him slightly 'larger' (hypostereo) by moving the cameras closer than the human IO (say by 10mm) and shoot the other guy in your commercial who is the 'loser' wearing the 'nobrand' aftershave - well, you could shoot him with a slightly larger I-O`(hyperstereo), again say 10mm - this might psychologically give an advantage to the 'hero'. I'll try it out and let you know if I get a script in for a 3d commercial.
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