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Difference between revisions of "Descriptor Proposed JFMR"

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(Implementation)
(Implementation)
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= Implementation =
 
= Implementation =
The implementation of a descriptor that use the phase portrait depends of the components <math>u</math> and <math>v</math> obtained of the simulation that allow to construct the equation system, although needed the gradient of  <math>u</math> and <math>v</math> to construct the system. With the system, we can calculate the determinant and the trace and can calculate <math>\lambda</math>
+
The implementation of a descriptor that use the phase portrait depends of the components <math>u</math> and <math>v</math> obtained of the simulation that allow to construct the equation system, although needed the gradient of  <math>u</math> and <math>v</math> to construct the system. With the system, we can calculate the determinant and the trace and can calculate <math>\lambda</math> using the next formula:
 +
 
 +
<math> \lambda_1,\lambda_2 = 0.5 (Trace(A) \pm \sqrt{Trace(A)^2 - 4det(A)})</math>

Revision as of 19:35, 19 September 2015

Definition

Given a vector field \vec{V}=(u,v), where u and v represent the components of the winds of each of the annotations.

The vector field representation allow to observe the behavior of the winds in a determined region, these behavior are represented as:

  • Vortex
  • Confluence
  • Difluence
  • Saddle Point

The meteorologists annotated the different configurations that it can present in a period of time and a level determined, this process was done with an annotations tool that allow to select this configurations.

Model Mathematic

Given a vector field \vec{V}, a way to classify this configurations is through the use of phase portrait, this method is used in the dynamic system to understand the behavior of functions of 2 or more variables. In computer vision is used in the detection corner, mammography and others.

This method allows to construct a equation system in which these can calculate the determinant and the trace.

 A =
\begin{bmatrix}
\frac{\partial U}{\partial x} & \frac{\partial U}{\partial y} \\
\frac{\partial V}{\partial x} & \frac{\partial V}{\partial y} \\
\end{bmatrix}

The trace and the determinant indicate as is the behavior of the system. To calculate the trace and determinant with their:

 Trace(A) = \frac{\partial U}{\partial x} + \frac{\partial V}{\partial y}

 det(A) = \left(\frac{\partial U}{\partial x} \frac{\partial V}{\partial y}\right) - \left(\frac{\partial U}{\partial y} \frac{\partial V}{\partial x} \right)

Implementation

The implementation of a descriptor that use the phase portrait depends of the components u and v obtained of the simulation that allow to construct the equation system, although needed the gradient of u and v to construct the system. With the system, we can calculate the determinant and the trace and can calculate \lambda using the next formula:

 \lambda_1,\lambda_2 = 0.5 (Trace(A) \pm \sqrt{Trace(A)^2 - 4det(A)})