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Having or formed by three planes meeting at a point.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Mathematics) having or formed by three plane faces meeting at a point
(Mathematics) a figure formed by the intersection of three lines in different planes
[C18: from tri- + Greek hedra base, seat + -al1]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(traɪˈhi drəl)

1. having, or formed by, three planes meeting in a point: a trihedral angle.
2. the figure determined by three planes meeting in a point.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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The observed scene contains nine targets: a sphere, three dihedrals, four trihedrals, and a cylinder.
Two trihedrals, within the same slant-range bin of 75 m, are put in the imaging scene (shown in Fig.
We employ the FDTD method to simulate the scattering data of a cylinder and a trihedral. Obviously, the cylinder is a BOR target.
Assume that the aperture collected from FDTD simulation is divided into 9 subapertures, the metrics of the near and far peaks of the cylinder and the trihedral using (2) are 2.1966, 2.1953 and 2.1619, respectively.
Although the ASE of the far peak of the cylinder is fluctuant due to the defocus problem mentioned above, it is much larger than the ASE of the trihedral for N [greater than or equal to] 7.
These subaperture images are linearly integrated to form traditional SAR image, in which the reflectivity of trihedral is much stronger than cylinder.
Analysis on all kinds of clutters is difficult and time-consuming, among which the trihedral is the most typical and significant one.
Therefore, plate, dihedral and trihedral consist of the dominating principal scatterers in a building.
Attributed Scattering Center Model (ASCM) is considered to be an effective way to identifying principal scatterers such as sphere, plate, dihedral and trihedral, etc.
This paper intends to develop an effective method to estimate the pose angle of the trihedral. Conventionally, we can get the pose angle of a trihedral in the echo-domain by probing into the amplitude ratio (AR) variety which is a function of the pose angle.
Section 3 presents a parametric back-scattering model for trihedral to build the relationship between AR and pose angle in the echo-domain.
However, the above symmetric feature is inapplicable for trihedral. The ratio will varies with [[theta].sub.P].