Accurate Measurement of 3D Positions and Orientations of Small LED-Cards by a Single Camera

Y. Seko, H. Hotta, Y. Saguchi, and T. Iyoda (Japan)


3D measurement, position and orientation measurement, computer vision, LED marker


We succeeded to measure the position and orientation of a small card with LEDs (light emitting diodes) accurately by capturing its image with a single camera at a video rate. The card consists of five LEDs that are arranged in a predetermined pattern: four LEDs are placed to form a 50-mm square and one is in the center of square with 8- mm height, which is a key factor to prevent false measuring of orientation. The camera has an image sensor of 1.2-mega-pixels and can captures images at 30 frames per second. Position and orientation of an LED card are measured by reconstructing 3D positions of LEDs in space from their images. Maximum errors of position measurement are 25.2 mm (0.63 percent in distance) for z-axis (optical axis of camera) and 5.5 mm for x-axis (horizontal direction), and that of orientation measurement is 1.5 degree in the case that LED cards are place at about 4 meters from the camera. We could measure the angle of the LED card accurately from -60 degree to +60 degree, which is robust measurement system of 3D position and orientation of card.

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