The lack of vertical parallax also causes objects in a rendered view to appear at slightly incorrect height. Besides, if you think about it, horizontal is often the dominant direction of motion for humans in most everyday situations (particularly during seated VR experiences) and for most tracking shots in TV production. This is generally acceptable because horizontal parallax tends to be more important for human stereo vision due to the relative position of our eyes. Moving up or down, however, they will not perceive vertical parallax as they would in real life. Consequently, a viewer only has five truly free degrees of freedom - three to turn their head and two to move in the plane of the capture circle. All captured viewpoints lie on a line (albeit a bent one: the capture circle), but there aren't any viewpoints in our dataset that would cover the vertical direction. And actually, there is a way to deal with limited background motion that we'll describe below.Īnother difference to a full light field with six spatial degrees of freedom (6 DoF) is that our array of source views is only one-dimensional. ![]() While this excludes certain use cases, it is rarely an issue for our purpose of creating backdrops for virtual reality that can then be populated with animated characters. Otherwise, ghosting artefacts would appear in views synthesised from inconsistent data. The most obvious limitation is that, because the camera moves, the scene itself must be perfectly still. The simplicity of our setup comes, of course, with a few trade-offs. Synthesising virtual views within the capture circle by sampling source views (not to scale) We can then synthesise views for virtual camera positions anywhere inside the capture circle from this dense set of source views. A typical diameter for the capture circle is one metre, which means that we effectively capture views less than 2mm apart. This results in a dataset that contains 1800 frames, or five frames per degree. A complete revolution takes 30 seconds, during which we record exposure-locked video at 60 frames per second. We use a motorised rig that slowly moves the camera around a horizontal circle. To be fair, we use a 360° camera, so there are multiple lenses involved, but the recorded panoramic images are each from a single viewpoint - they just happen to have a larger field of view. Single-camera Light Fieldsģ60° camera moving on a horizontal circle, capturing about five frames per degree.Īiming for a simpler system that fits with established broadcasting workflows, we took a slightly different approach (based on concentric mosaics), deciding to capture our light fields with a single camera. This planar array then acts as a virtual window through which the scene can be viewed by recomposing and interpolating between light rays that were actually captured.Īs long as the lenses are packed sufficiently close together, arbitrary rays falling through that window can be interpolated from the source data. ![]() Typically, a light field is captured with a dense array of cameras arranged on a plane, all pointing in the same direction (or, equivalently, with an array of lenslets in front of a single camera that split the image into multiple views). In virtual reality, these additional degrees of freedom make all the difference! This adapts to your movements, allowing you to see view-dependant details that are vital for a realistic portrayal of an environment, such as parallax (closer objects moving more relative to head motion than those far away), reflections and occlusions. However, a light field gives you six degrees of freedom (turning your head as above, plus moving forward/backwards, left/right and up/down). A 360° panorama only allows you to look around by turning your head (three degrees of freedom: pan, pitch and roll) but not to move anywhere other than the exact spot where the camera was - as if your head was stuck inside a huge balloon fixed to your shoulders. Unlike a 360° panorama that only captures light rays that come into a single point (the camera position), a light field contains many(!) more rays travelling through space all over the place. Light field background with animated foreground character What is a Light Field?Ī light field is a collection of light rays so dense that arbitrary views can be recreated from it.
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