Spherecam

Spherecam system design

The Spherecam system enables numerous camera configurations, depending on the desired vertical field of view, image resolution and presentation architecture (cylinder, dome, etc.).

spherecam_clusters
Spherecam cluster configurations

feild of view - spherecam
Vertical field of view of different Spherecam configurations

overlap_regions
Overlap regions 8×4 horizontal configuration and 7×0 vertical

To be able to stitch a seamless panoramic or spherical image from multiple camera images, the system has to be calibrated. In calibration the camera’s internal geometric and optical characteristic (intrinsic parameters: focal length, lens distortion, centre of distortion, aspect ratio), and orientation relative to a specific world coordinate system (extrinsic parameter), are defined. This data forms the basis for the interpolation of the stitched panoramic/spherical image by correcting the individual camera image distortions and distributing their location based on the extrinsic parameters. The result after edge-blending the individual images is a seamless panoramic/spherical frame.

pano_grid
Panoramic frame with calibration board and distortion mesh

system-diagram
Spherecam system diagram (download PDF)

In terms of the post-production system, the recorded data from all cameras is in raw Bayer format and stored as a binary stream. To generate color images, a Bayer demosaicing algorithm is applied and individual frames are stored as RGB bitmaps. Based on the calibration data the individual camera frames are optically corrected, stitched and edge blended to form a seamless cylindrical or spherical frame.

post_workflow
Post processing workflow