More GPU wonders — Hough and Radon

In yesterday’s post, we saw how optical flow — once only reserved for off-line, compute-intensive applications — can be performed in real-time on GPU hardware. Another type of visual computation is the Hough and Radon transforms. A lot of the expense of a CAT scan machine is actually the computational hardware. The “computer-assisted” part of the CAT scan name takes a series of 1D views and fuses them into a 2D slice. The slices are “stacked” to form the familar though-the-body views a technician would see during and after a scan. The magic behind this is the Radon transform, which is very closely related to the Hough transform.

Now, with a GPU, you don’t need a multimillion dollar CAT or PET scan machine to see Hough (pronounced “huff”, in case you’re scratching your head about how to pronounce it!) transforms in action. A consumer GPU is all that is required:

This clip is interesting as it shows one of the basic uses for the Hough transform on video — finding prominent, straight lines. In turn, this is useful for finding the “vanishing point” — the point where lines going more distant from the viewer converge. If you’ve taken a drawing class, you’ve heard of this before. This, in turn can be used for automatic 2D video to 3D-stereo video conversion, object segmentation, and tracking objects in a scene. The lines can also be used for a “cheaper” form of optical flow computation.


~ by opticalflow on February 10, 2009.

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