We built and developed our own technology solutions, using cost saving consumer computing on open source platform. Both renderer and motiontracker is running Linux distribution on typical PC gaming computers, with off the shelf graphics cards also intended for games.
Cameras are stripped and modified consumer fire-wire web-cameras adding synchronization so that all four shutters open and close at the same time.
Motiontracking
The motion tracker computer watches the audience through four fire-wire cameras equipped with infra-red filters. The helmets are mounted with super-bright infra-red LED's, each modulating it's brightness with it's own unique finger-print id-code.
Rendering
MRI volumetric images consist of a 3-dimensional volume of voxels each describing the hydrogen proton density in each position. Different tissues can be separated by their densities making different kinds of tissues clearly visible. MRI volumetric images is rendering using raycasting from each pixel of the screen through the volume, integrating attenuation along the path of the ray alternatively calculating gradients and shading the volume with light.
Ray casting is done with fragment shaders on the GPU of the consumer graphics card providing us with a tremendous amount of processing power.
headtracker helmet
helmet printed circuit board
mirror frame
tracking and rendering video
colored MRI projection screenshot
helmet scematics