What Gordon said. Nvidia has some things you might be able to make use of for object recognition and tracking. It all comes down to budget and a lot of details/requirements yet to be stated. Restaurants are doing this indoors with rf (apparently). Indoor positioning is an interesting subject, but may or may not provide much useful input to you. Michael Brown N5QMG --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .