Abstract: A marker system includes: a first marker; and a second marker; wherein the first marker and the second marker are configured to emit light from one or more light sources coupled to the first marker and the second marker; and wherein the first marker and the second marker are configured to emit the light for detection by a camera. A method performed using a marker system includes: generating light using one or more light sources; emitting the light at a plurality of markers that are coupled to the light sources; and detecting the light emitted from the plurality of markers using a camera; wherein the act of detecting comprises using one or more filters to reduce ambient light to a level that corresponds with a noise level of the camera while allowing light emitted from the markers to be imaged by the camera.

Abstract: A marker system includes: a first marker; and a second marker; wherein the first marker and the second marker are configured to emit light from one or more light sources coupled to the first marker and the second marker; and wherein the first marker and the second marker are configured to emit the light for detection by a camera. A method performed using a marker system includes: generating light using one or more light sources; emitting the light at a plurality of markers that are coupled to the light sources; and detecting the light emitted from the plurality of markers using a camera; wherein the act of detecting comprises using one or more filters to reduce ambient light to a level that corresponds with a noise level of the camera while allowing light emitted from the markers to be imaged by the camera.

Abstract: Embodiments of this invention include a shoe having removable or interchangeable heels. Some embodiments have a low heel and a high heel, each having mechanisms for attaching and detaching said heel(s) from said shoe. Further embodiments include a shoe body having an expandable element, permitting the shoe body to attain a shape suitable for low heel configuration, and permitting the shoe body to change shape to accommodate a high heel configuration. Embodiments of this invention thereby permit a person to wear a single pair of shoes, carry one or more pairs of heels, and change the heels to either low heel or high heel shoes. Such embodiments eliminate the need for a person to carry a multiplicity of pairs of shoes.