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Speckle noise is shown to constitute a fundamental limit to laser range finders based on triangulation. A model is derived that relates the magnitude of this noise to the optical geometry used. Synchronized laser scanners are shown to have inherent speckle noise reduction properties. Experimental results are presented.

This paper describes a system for simultaneously measuring the 3-D shape and color properties of objects. Range data are obtained by triangulation over large volumes of the scene, whereas color components are separated by means of a white laser. Details are given concerning the modeling and the calibration of the system for bidirectional reflectance-distribution function measurements. A reflection model is used to interpret the data collected with the system in terms of the underlying physical properties of the target. These properties are the diffuse reflectance of the body material, the Fresnel reflectance of the air-media interface, and the slope surface roughness of the interface. Experimental results are presented for the extraction of these parameters. By allowing the subtraction of highlights from color images and the compensation for surface orientation, spectral reflectance modeling can help to understand 3-D scenes. A practical example is given where a color and range image is processed to yield uniform regions according to material pigmentation.

The bandpass of spectrometers can cause appreciable errors when making radiometric measurements. This paper describes a practical method for correcting a set of equispaced measured values provided by a spectrometer with a finite bandwidth, an arbitrary bandpass function and at an arbitrary wavelength step. The paper reviews the limits of the approach for real spectra in the presence of measurement noise and suggests ways of reducing the effect of noise.

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