Banca de DEFESA: ROSA JANETH ALPALA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: ROSA JANETH ALPALA
DATA : 28/07/2025
HORA: 16:00
LOCAL: Remoto
TÍTULO:

Identifying Heterogeneity in SAR Data with New Test Statistics

PALAVRAS-CHAVES:

SAR; heterogeneidade; entropia; coeficiente de variação; testes de hipóteses

PÁGINAS: 85
RESUMO:

This work presents a statistical approach to identify the underlying roughness characteristics in synthetic
aperture radar (SAR) intensity data. The physical modeling of this kind of data allows the use of the
Gamma distribution in the presence of fully-developed speckle, i.e., when there are infinitely many
independent backscatterers per resolution cell, and none dominates the return. Such areas are often
called ``homogeneous'' or ``textureless'' regions. The GI0 distribution is also a widely accepted law for
heterogeneous and extremely heterogeneous regions, i.e., areas where the fully-developed speckle
hypotheses do not hold. One issue involving the parametric space of GI0 is the analytical infeasibility of
testing homogeneity against heterogeneity using classical tests. As solutions to this problem, we
propose three test statistics to distinguish between homogeneous and inhomogeneous regions, i.e.,
between Gamma and GI0 distributed data, both with a known number of looks. The first test statistic
uses a bootstrapped non-parametric estimator of Shannon entropy, providing an assessment in
uncertain distributional assumptions. The second test uses the classical coefficient of variation (CV). The
third test uses an alternative form of estimating the CV based on the ratio of the mean absolute
deviation from the median to the median. We apply our test statistic to create maps of p-values for the
homogeneity hypothesis. Finally, we show that our proposal, the entropy-based test, outperforms
existing methods, such as the classical CV and its alternative variant, in identifying heterogeneity when
applied to both simulated and actual data.

MEMBROS DA BANCA:
Externo à Instituição - SAEID HOMAYOUNI
Externo à Instituição - PAOLO ETTORE GAMBA
Presidente - 2224108 - ALEJANDRO CESAR FRERY ORGAMBIDE
Externo à Instituição - ANDERSON A. DE BORBA
Externa à Instituição - FÁTIMA NELSIZEUMA SOMBRA DE MEDEIROS - UFC