Accurate sensor location is necessary to properly model the EEG measured from scalp as well as intracranial electrodes. Accurate sensor position knowledge is also required for multimodal registration of functional electrophysiological data with other neuroimaging data including MRI, CT, fMRI, PET, and SPECT. We propose to build a 3D imager with the following features: low cost, fast data acquisition, cross-platform availability, registration with MRI and integration with computer assisted neurosurgery. We will produce a prototype system that will be aimed toward neuroimaging applications. It will calculate the 3D location of scalp sensors using a non-contacting photogrammetric method and capture the head and face surface not obscured by hair. It will use low cost CCD cameras mounted on an open, rigid frame suspended over a subjects head after electrode placement. The controlling computer will rapidly select each camera in turn, digitize and save its image. Special software written will then identify corresponding points in multiple images and compute and display the 3D coordinates of each sensor and selected facial points. This device will enable research and clinical neurophysiologists to easily and rapidly measure electrode positions. It will find special application in the areas of pediatrics, long-term monitoring, and computer assisted neurosurgery. PROPOSED COMMERCIAL APPLICATION: Researchers and clinicians performing realistic modeling and visualization of multielectrode electrophysiology (neuroimaging) and multimodal integration all require a way to measure sensor positions. Our product will be specialized for neurophysiology and will be more cost effective for this area than any other known product available at this time.