Ultra-Wide Stereo Vision — Not a Question of Perspective 7 months ago

Why Should You Use 3D Vision?

Simply, because our world is 3D! 2D images only provide limited information. By dropping the third dimension, useful depth information is irretrievably lost. You see, when a 2D image of a spherical object (e.g. a ball) is captured, it is not projected as a circle. Conversely, no algorithm could retrieve the real ball from a circular shape.

 

Image shows 3D data captured with HemiStereo NX depth sensing camera. Since the Cartesian coordinates are stored together with the color information the viewers point-of-view can be changed afterwards.

Can 3D Cameras See Everything?

Straight Lines Have to be Straight — Sure?

Limited field-of-view due to rectilinear projection.

How to Overcome This Limitation? — HemiStereo®

Note: Angle of incidence θ is measured from center to the line of incidence, while FOV is commonly defined from side-to-side. Hence FOV = 2 ⋅ θmax.

The relationship between these two variables is given by the underlying projection model:

Projection functions compared — For θ=90° tangent runs towards infinity.

And what do we learn from that? When comparing the plot of both projection formulas in the chart below, we can observe the following: When θ approaches 90° (FOV heads for 180°) the distance ⍴ heads towards infinity in perspective projection. In other words: To display 180° FOV with a common camera, it needs to be equipped with an infinitively large image sensor!

Illustration: How HemiStereo NX sees the world.

Coming back to the collision avoidance example above, we are now able to perceive obstacles and people in an 180° environment and warn the driver in case of imminent danger: