19 Oct 2003 motters   » (Master)

I've updated some of the primal sketch stuff which I started a couple of years ago, and used it for detection of box-shaped objects and geometric scene analysis.

In a simple test the geometric information from primal sketches can be used for recognition of different scenes. I had Flint look left, right and straight ahead and remember what he had seen. I then dissconnected power to the servos and manually moved his head into different positions, then had him guess in what direction he was looking based only upon what he could see. With some tweaking of weightings the recognition is pretty much completely reliable. These are only basic tests, but they do prove that relative geometry matching methods work.

I've found the best way to test any new vision algorithm is firstly to test it with natural lighting during the day, then close the curtains and switch on artificial lights and check if the recognition still performs in the same way. Under artificial lighting the contrast decreases and the apparent colour of things changes quite substantially, so most vision systems fail to generalise between the two lighting situations. By using a primal sketch this problem is greatly reduced, since only edges information is considred, with the edge detection threshold adjusting automatically as contrast reduces.

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