Prakash: Lighting-Aware Motion Capture Using Photosensing Markers and Multiplexed Illumination

R Raskar, H Nii, B de Decker, Y Hashimoto, J Summet, D Moore, Y Zhao, J Westhues, P Dietz, M Inami, S Nayar, J Barnwell, M Noland, P Bekaert, V Branzoi, E Bruns

ACM SIGGRAPH 2007Paper

Abstract

In this paper, we present a high speed optical motion capture method which can measure three dimensional motion, orientation, and incident illumination at tagged points in a scene. We use tracking tags that can be imperceptibly embedded in attire or other objects and can work in natural lighting conditions. Our system can support an unlimited number of tags in a scene, and each tag has a unique id thus eliminating marker reacquisition issues. Our tags also provide incident illumination data which can be used when inserting synthetic elements in order to match the lighting of the scene at the time of capturing. This makes the technique ideal for on-set motion capture or the real-time broadcasting of virtual sets.

Unlike previous methods that employ high speed cameras or scanning lasers, we capture the scene appearance using the simplest possible optical devices – a light-emitting diode (LED) with a passive binary mask used as the transmitter and a photosensor used as the receiver. We strategically place a set of optical transmitters to spatio-temporally encode the volume of interest. Photosensors attached to scene points demultiplex the coded optical signals from multiple transmitters, allowing us to compute not only their location and orientation but also their incident illumination and the reflectance of the surfaces to which they are attached. We use our untethered tag system to demonstrate methods of adding special effects to captured videos that cannot be accomplished using pure vision techniques that rely on camera images.