[1] The fragile and unique nature of meteoritic material requires a method of density measurement that is accurate yet nondestructive. This is difficult to achieve using conventional methods. In this study, the bulk density of eleven meteorite fragments which vary in shape, size, surface roughness, porosity, and reflectance has been determined using three-dimensional (3-D) laser imaging. An auto-synchronized laser camera raster scanned the surface features of each meteorite without contact and to a high degree of precision. Visualization software was used to align several scans into a closed model and to compute its volume. The mass having been predetermined, the density was then easily computed. Three-dimensional laser imaging is the least invasive method of density measurement currently in use. The precision of the approach is less than 1%. The densities determined using 3-D laser imaging compare very well with previously published values, based on a variety of different measurement techniques. The average difference is 3.4% and can be attributed to the presence of heterogeneities and to the limited amount of comparative data available. For nine out of the eleven samples studied, the densities determined using 3-D laser imaging are higher than previously published results. Friction between fluid and container, and bead compaction might have led to an overestimation of the volume measured using Archimedean methods. In addition to volume measurements, 3-D images of rock samples can yield detailed information on surface properties from a distance. The technique could be used for semiautonomous planetary geological exploration.

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This paper presents the most up-to date experimental results obtained during the integration of a 3-D Laser Scanner Tracking System and the current Space Vision System used by NASA. Half scale models of modules of the Space Station Freedom have been built for this demonstration and comparison between the current method using video cameras and the Laser Scanner System are presented. The variable resolution laser scanner can track, in real time, targets and geometrical features of an object. The Laser Scanner System uses two high-speed galvanometers and a collimated laser beam to address individual targets on the object. Very high-resolution images and excellent tracking accuracy are obtained using Lissajous figures that provide high pointing accuracy of a laser beam. The prototype automatically searches and tracks, in 3-D, targets attached to the object. The locations of the centroid of the detected targets are fed directly into the existing photosolution and attitude control modules of the Space Vision System (SVS).

/npsi/ctrl?action=rtdoc&an=5764234&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=5764234&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRC Simulation, and Controls (AeroSense 2002), 4714, 2002 Imaging and Tracking Elements of the International Space Station using a 3D Auto-Synchronized Scanner Samson, C.; English, C.; Deslauriers, A.; Christie, I.; Blais, François Permission is granted to quote short excerpts and to reproduce figures and tables from this report, provided that the source of such material is fully acknowledged. Imaging and tracking elements of the International SpaceStation using a 3D auto-synchronized scanner ABSTRACTThe Neptec Design Group has developed a new 3D auto-synchronized laser scanner for space applications, based on a principle from the National Research Council of Canada. In imaging mode, the Laser Camera System (LCS) raster scans objects and computes high-resolution 3D maps of their surface features. In centroid acquisition mode, the LCS determines the position of discrete target points on an object. The LCS was flight-tested on-board the space shuttle Discovery during mission STS-105 in August 2001. When the shuttle was docked on the International Space Station (ISS), the LCS was used to obtain four high-resolution 3D images of several station elements at ranges from 5 m to 40 m. A comparison of images taken during orbital day and night shows that the LCS is immune to the dynamic lighting conditions encountered on orbit. During the mission, the LCS also tracked a series of retro-reflective and Inconel targets affixed to the Multi-Purpose Lab Module (MPLM), when the module was stationary and moving. Analysis shows that the accuracy of the photosolutions derived from LCS centroid data is comparable to that of the Space Vision System (SVS), Neptec's product presently used by NASA for ISS assembly tasks.

3D ranging and imaging technology is generally divided into time-based (ladar) and position-based (triangulation) approaches. Traditionally ladar has been applied to long range, low precision applications and triangulation has been used for short range, high precision applications. Measurement speed and precision of both technologies have improved such that ladars are viable at shorter ranges and triangulation is viable at longer ranges. These improvements have produced an overlap of technologies for short to mid-range applications. This paper investigates the two sets of technologies to demonstrate their complementary nature particularly with respect to space and terrestrial applications such as vehicle inspection, navigation, collision avoidance, and rendezvous & docking.