| Sensors
on 3D Digitization |
Definition
Machine vision involves the analysis of the properties of the luminous flux reflected
or radiated by objects. To recover the geometrical structures of these objects,
either to recognize or to measure their dimension, two basic vision strategies
are available [1]. Passive vision, attempts
to analyze the structure of the scene under ambient light. [1] Stereoscopic vision
is a passive optical technique. The basic idea is that two or more digital images
are taken from known locations. The images are then processed to find the correlations
between them. As soon as matching points are identified, the geometry can be computed.
Active vision attempts to reduce the ambiguity of scene analysis by structuring
the way in which images are formed. Sensors that capitalize on active vision can
resolve most of the ambiguities found with two-dimensional imaging systems. Lidar
based or triangulation based laser range cameras are examples of active vision
technique. One digital 3D imaging system based on optical triangulation were developed
and demonstrated. AUTOSYNCHRONIZED
SCANNER The auto-synchronized scanner,
depicted schematically on Figure 1, can provide registered range and colour data
of visible surfaces. A 3D surface map is captured by scanning a laser spot onto
a scene, collecting the reflected laser light, and finally focusing the beam onto
a linear laser spot sensor. Geometric and photometric corrections of the raw data
give two images in perfect registration: one with x, y, z co-ordinates and a second
with reflectance data. The laser beam composed of multiple visible wavelengths
is used for the purpose of measuring the colour map of a scene
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