Projected silhouette

I l.A good physical exercise program will help you transmit a better image to others. You will project a more trim silhouette because exercising helps you stand straighten This will enhance your personal pride and give you more confidence to take charge of your life. 

Figure 6.17 A three-dimensional color gamut projected onto the plane b = 1. The resulting two-dimensional gamut is simply the silhouette of the three-dimensional gamut when viewed from the origin.

The primary size measurement is based on the area of the silhouette. A simple count of the pixels and the consideration of the calibration (pm2/pixel for example) give the projected area, A. This is valid for any cell, even elongated ones [76]. Geometrical correction might be necessary to take into account the shape of the support, like in the case of spherical microcarriers [77]. An equivalent diameter (Deq) is subsequently calculated ... 

Beddow [42] showed how a number of particle silhouette shapes could be analyzed and reproduced by Fourier transforms. Gotoh and Finney [52] proposed a mathematical method for expressing a single, three-dimensional body by sectioning as an equivalent ellipsoid having the same volume, surface area and projected area as the original body. 

All that is normally known about a particle is its silhouette, projection, or profile or, in those cases where size is derived from other physical effects, such as, for example, the settling velocity, a dimension related to voliune, mass, or surface texture. Therefore, methods must be found that interpret information from cuts through the particle, scans of portions of the surface area, or information from particle behavior in, for example, fluids and connect it with overall shape. Unless the measured outline of the particle misses a unique, dominant feature of the particle shape, the result will be representative of the particle. The methods are stiU very complicated and require a large number of discrete items of information to describe a particle signature reasonably well. 

In general, human silhouette information is commonly employed to represent human activities [1]. In fact, human activities can be considered as temporal variations of human silhouettes. In addition to silhouette shape, motion information is also used. Optical flow is defined as the apparent motion of individual pixels on the image plane. It often serves as a good approximation of true physical motion projected onto an image plane. 

For some applications, a library of two-dimensional silhouette projections that represent three-dimensional objects can be conveniently stored. For the recognition of three-dimensional objects with a small number of stable orientations on a flat table, this representation is ideal—if the object silhouettes are sufficiently different. For example, silhouettes have been used to recognize aircraft in any orientation against a well-lit sky background. However, because many different three-dimensional-object shapes can possess the same silhoutte projection, this type of representation is not a general-purpose technique. 

The utility of microscopic size measurements of irregular particles often depends on the ability to convert the measured sizes to other equivalent diameters that describe the behavior rather than the geometry of the particles. The most useful of these diameters is the equivalent volume diameter, which can be combined with the dynamic shape factor (Section 3.5) to describe the aerodynamic properties of a particle. The volume shape factor relates the voliune of a particle, v, to one of the silhouette diameters described before and is defined, for the projected area diameter, by... 

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