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Minimum Subject Distance

jonbetzfilms
Sun, 04 Oct 2015 17:27:45 GMT

Hi all, The original article on VRColony about the 18-camera VR rig cited a minimum subject distance of a little over 5 ft, similar to the 360Heros 3D 360 VR mounts. I am interested in developing a VR rig with 3D 360 capability for remote camera trap use to film wildlife, so I need to optimize for low minimum subject distance (often the most compelling content results from wildlife investigating the rig or getting close). I have seen examples from companies offering wildlife experiences, but they would not offer info about their rigs (but did mention intensive stitching work). Is it possible to minimize minimum subject distance to something closer to 1 ft while maintaining a 3D experience? The mono "full dome" type footage I have seen is far less compelling in VR than 3D, so I would like to stay in the 3D realm if possible. Is this something that can be optimized in post-production in a shot-specific way using a rig with an inter-lens distance of 55 or 65mm? I ha ven't previewed the VRColony example shots in VR goggles, but there appear to be significant minimum subject distance issues like ghosting. Can this be avoided or corrected? Thanks so much.

Paul Armstrong
Thu, 08 Oct 2015 03:28:17 GMT

Jason from VRColony is working on a wide angle lens solution that will reduce the number of cameras (6) and probably reduce the minimum subject distance. But you'll never get 1ft minimum distance with these rigs. Your best option (IMO) is a 2 camera rig. With fast moving objects, and without global shutter, your going to have nightmares the more cameras you have! In the end, you need to decide what's more important. Easier content creation and freedom, less noticeable errors, more usable footage, high resolution playback, reduced minimum subject distance and simple post production OR 360 3D that is a ton of work and will ALWAYS have issues, unless you have a highly skilled team of post production geniuses. Even then, it'll display at half the resolution of 2D. iZugar have wide angle camera rigs similar to what Jason is working on. But they are GoPro, not Yi. They have 2, 3 and 6 camera rigs. The 6 camera is 3D 360, probably very similar to what Jason is buil ding. Here's an iZugar demo on the 2 camera rig, and you can see the minimum subject distance is about 1ft like you need. https://www.youtube.com/watch?v=LoeGnUP7A7o iZugar website: http://www.izugar.com

jreinjr
Sat, 10 Oct 2015 17:49:53 GMT

Thanks Paul! Good info here. Jon, your project sounds really interesting - candid wildlife photos/video would be an incredible subject for 3D 360 VR. It sounds like you'd be looking at some degree of customization to your rig - to remotely power-on your cameras, for example. The 18-camera rig I've posted about on this site has a minimum subject distance of about 5 feet, like you've posted. If you lose the 3-camera zenith and go with 1 or 2 cameras on top, you can get all the lenses closer together - with no space between stereo pairs. The camera I'm about to Kickstart has a closer minimum distance, and a more 'round' 3D effect (objects are less like cardboard cutouts). I need to run for now, but I'll be back later to talk about addressing ghosting in post - you have some options, sometimes :)

jreinjr
Sun, 11 Oct 2015 05:02:33 GMT

Alright, so here's one method I've used to address ghosting from subjects being too close to the camera. As you know, the greater the parallax between left and right eye images, the 'closer' the subject will appear. At infinite distance (distant background), there should be no visible difference between left and right eye images. If there's too much parallax with close subjects, one option is to slide one view horizontally, to shrink this distance. For example, sliding the 'right-eye' view to the right shrinks the parallax of close subjects, and a slight adjustment here helps you resolve this image. However - this approach negatively affects the stereo perception of any distant background in your scene. If your distant background was originally identical between left- and right-eye images, shifting one image in this way [will tow your eyes out like this.](//muut.com/u/vrcolony/s1/:vrcolony:lM55:1362135219_franken02.jpg.jpg) So, it's not a good choice for many situations, but for shots where you lack di stant backgrounds (interiors, or possibly even a forest clearing) it can help address accidental ghosting from subjects too close to the camera.