Why use more than 2 perspectives for a 3D image?


Every time I go out with my camera rig I get asked the same question: “why do you have so many cameras?”.

The answer is actually somewhat complicated. A 3D motion picture is created with two cameras and each camera’s image is presented discretely to each eye by the use of polarized filters or in the case of home 3D capable TV’s they would be shutter glasses in many cases.

If you want glasses-free 3D viewing then the ability to discretely show a single image to each eye is more difficult. And if you can move while looking at the photograph then something weird happens. Try this at your next 3D movie! Get up and walk around while looking at the 3D movie. The images follow you around because your perspective in space is fixed. It is a very weird sensation.

If you aren’t fixed to a chair and are walking around then you have a constantly changing perspective in real life. Holograms provide a pure seamless array of perspectives. A fantastic feature but as I have mentioned elsewhere on this site, holograms are very limited in terms of the pictures you can take and do not have real world colors or any color accuracy at this point in development.  A lenticular lens array approach makes it possible to direct different images to each eye (that’s what the lens on the print overlay does). The smoothness of transition from one perspective to the next is a direct function of the number of cameras you have. More cameras provide a smoother transition from perspective to perspective. As you look at a lenticular and move, you see a change in perspective that can compare to what you see in real life. (In my photographs, I take great pains to make sure that is the case – but practically everyone else does not consider this important). If you are going for an effect then I suppose it isn’t important. But if you are trying to emulate reality then it is extremely important.

Providing the experience of multiple perspectives greatly enhances the realism of a 3D image and why I believe the 2 perspective approach used at the movies will eventually go away as it is more limiting.

Want to know more? Comment with questions and I’ll be glad to tell you what I have found out and experienced through trial and error.

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2 Comments

Filed under 3D Photography

2 responses to “Why use more than 2 perspectives for a 3D image?

  1. Daniel

    Dear Mr. Green,

    I’ve just discovered your blog in the last few days as I’m dabbling in stereo photography, and recently printed a few lenticular images. Your philosophy resonates quite strongly with my discoveries and experiences so far. I have built a very primitive mirror box for a 2 camera setup and now designing a 4 camera rig. I’ve been using an android app to calculate stereo budget but find that more suited for screen than print. Any info you’re willing to share regarding the rig or calculations would be greatly appreciated, and my apologies if this is on your site and I’ve missed it, there’s a lot of interesting articles to get through.

    Kind Regards,
    Daniel

    • The people who profess all the knowledge on “how to do it”, don’t. There are no rules except for the ones that are percolating out there that need to go away. Tools and instruction do not make magical imagery. That only comes through experimentation and experience. There are basics, like understanding how a lenticular lens works and how the print interacts with the lens. But that is understood in a much better way through experience because you see things that the books don’t talk about.

      Pretty much everyone has an opinion on best practices and how to do it. I start by looking at what I’ve created and making note of what I like and what I don’t like. I stop doing the things I don’t like and I work to improve the things I do like.

      As to calculations, in general you have between 4″ and 18″ of depth you can depict in a lenticular before the cross talk becomes a distraction. Having more perspectives generally is a good thing. I use 36 cameras to shoot 36 perspectives, but it is possible to get good results with as few as 9 cameras. I’ve yet to see anything spectacular with interpolated views unless the original was a computer model in which case the views aren’t interpolated.

      Camera spacing relates directly to resolution and the final size of the image. Generally speaking, you need to determine the crosstalk point of the lenticular lens you are using and work backwards from that with regards to camera spacing keeping in mind how “natural” you want the imagery to appear (which, for me isn’t all the time).

      There are as many ideas as there are people – I would encourage you to develop your own ideas! Look at your work and if it offends you, find out why and always try to make it better. As to interlacing software – I opted to create my own because I wasn’t satisfied with what was available. That doesn’t mean you can’t find software that is exceptional – I’ve just found that there were too many limitations for the work I’m trying to do.

      If you are in Australia, you should look up Mark Ruff http://www.timesplice.com.au I don’t necessarily agree with his approach as it relates to what I do, but he is very knowledgable and has been around for a while. Last but not least, you should spend some time reading about stereo vision. There’s a lot more there than meets the eye (pun intended).

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