Friday, November 18, 2016

Hemispherical vs. Spherical 360 cameras: how their shots differ in VR and tiny planet photos




      In this post, I explore a couple of ways to use a hemispherical 360 camera, and how its usage differs from a spherical 360 camera for VR and tiny planets.


      I've had several 360 cameras, but I had only one 360 camera that was hemispherical (the X360).  For me, hemispherical cameras just seemed too limiting.  When I got the Kodak SP360 4k Dual Pro, it gave me a chance to experiment with hemispherical cameras with a decent camera.


VR VIEW
      I found that with one hemispherical camera, particularly one with a larger field of view such as the SP360, you can get usable 180-degree VR.  The SP360 4k app allows you to export a hemispherical 360 image in equirectangular format, the standard format for viewing images in most VR headsets.  Besides a horizontal hemispherical 360 image taken with the camera facing upward, the app also allows you to take a forward-facing vertical hemispherical 360 image, which I think is more useful than an upward-facing horizontal hemispherical 360 image.

horizontal hemispherical 360 image



vertical hemispherical 360 image

      A vertical hemispherical 360 image fills the user's field of view, putting the blind spot directly behind the user.  This could be useful for situations where you would prefer not to include yourself in the shot, or if you are using equipment such as reflectors or LED lights.


Here is a sample of a vertical hemispherical 360 image:


Sharing the hemispherical image is just as simple as it is with a spherical image.  In this case, I just uploaded the hemispherical equirectangular JPG to Kuula.co, which processed the image as a spherical 360 image.





LITTLE PLANETS AND RABBIT HOLES
      I'm fond of using 360 cameras to make little planets and rabbit holes.   With a hemispherical 360 camera, you can also make rabbit holes.  To take a rabbit hole shot with a hemispherical camera, the camera should be aimed at the middle of the rabbit hole.  For example, if the intended middle of the hole is the sky, then your camera should be pointed upward.

      Note, however, that a hemispherical rabbit hole will be much smaller than an equivalent rabbit hole from a fully spherical camera.  Here is a rabbit hole from a fully spherical 360 camera (the Ricoh Theta m15):

      Here is a similar rabbit hole, with a hemispherical 360 camera (the SP360 4k):

      Note that this was the widest rabbit hole that I could get with the hemispherical shot (note further that the SP360 has a 235-degree FOV, so a 180-degree camera would have an even narrower rabbit hole).  This was the uncropped version:

      As for little planets, they are much harder to take with a hemispherical 360 camera. The issue is that the camera has to be positioned high and needs to capture the ground.  With a fully spherical camera, this is not a problem because it captures everything around it.  Moreover, the tripod can be positioned at the stitch line, making it essentially invisible.

      With a hemispherical camera, capturing the ground requires the camera to be aimed downward, which in turn leads to another problem: how to position the hemispherical camera.  If you use a tripod or selfie stick, the tripod or selfie stick will be featured prominently in the shot.  To keep the tripod or selfie stick outside of a little planet shot on a hemispherical camera, you'll need a drone or similar device, making it much more difficult to take a shot that is easily captured on a spherical camera.

      Because of a hemispherical 360 camera's limitations, I still much prefer a spherical 360 camera.  However, there are situations where a hemispherical 360 camera would be almost as good as a fully spherical 360 camera.