High Dynamic Range Photogrammetry for Light and Geometry Measurement

Abstract

When people perceive the world, their eyes simultaneously acquire light and geometry to constitute an image that is interpreted in the brain as vision. The real-time synchronous measurement of light (in photometry) and geometry is desired in many scientific and industrial applications related to visual perception. Conventionally, meters and tools have been used for measuring light and geometry. Digital cameras can also measure light or geometry, such as recently validated high dynamic range (HDR) photography for luminance mapping a static scenario, and metric-camera-aided photogrammetry for measuring geometry. Unfortunately, existing technologies cannot measure light and geometry simultaneously. The separated measurements increase the labor, slow the data collection, and cause difficulties in follow-up data alignment. To break through these limitations, HDR photogrammetry was recently developed for synchronous acquisition of luminance of targets across a scene and their three dimensional coordinates XYZ in the field. The HDR photogrammetry deploys a single consumer grade digital camera fitted with a standard, wide-angle, or fisheye lens, mounted on a portable measurement platform. The HDR photogrammetry was validated in a laboratory experiment. The average errors of 1.8% – 6.2% for luminance mapping seven grey checkers and 12.9 – 24.3 mm for measuring their XYZ coordinates are deemed acceptable in practice. The HDR photogrammetry would supplement light and geometry measurement and stimulate many applications. This paper introduces several indoor and outdoor applications of the HDR photogrammetry, using a Canon EOS Rebel T2i fitted with a 10 mm Sigma EX DC HSM fisheye lens as the main test rig, for measuring light and geometry simultaneously.