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| Titel |
Sensivity analysis of geometrical and topological parameters to the thresholding soil images |
| VerfasserIn |
A. M. Tarquis, M. E. Sanchez, J. M. Antón, J. Jimenez, Antonio Saá-Requejo, D. Andina, J. W. Crawford |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064695
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| Zusammenfassung |
| The sensitivity of mass fractal dimension (Dm), a spectral dimension (d), and the ratio of the
two, (-d-
Dm), that relates to the scaling property of dynamical processes in soil such as
diffusion, to different threshold criteria was estimated. In order to do so, intact soil samples
were collected from four horizons of a Brazilian soil and 3D images, of 45.1 mm resolution
(256x256x256 voxels), were obtained. Four different threshold criteria were used to
transform CT grey-scale imagery in binary imagery (pore/solid), based on the frequency of
CT units.
To compare the effect of threshold and soil horizons on the two parameters studied and its
ratio, an analysis of variance was performed in a split-plot design. In this study each image is
the “main plot unit” where we have performance four determinations of the parameters.
Therefore, it was considered the three locations as blocks, each horizon as main plot
effect and each threshold as subplot effect. GenStat® version 12.1 was used to
performance these analysis. The significance level of all the statistical analysis was at
5%.
Fractal-like scaling was observed overall length scales, however the effect of thresholding
on the estimate for Dm depended on the range of length scales used. The log-log plots, from
which Dm is estimated, show that thresholding influenced mainly the scaling at the smallest
length scales (of size length from 1 to 16 voxels). This demonstrates that different
thresholding schemes mainly influence the features close to the resolution limit of the
image.
Dm and d showed a relation with the apparent porosity (i.e. the value calculated for
different threshold criteria) in the image for the 12 samples studied. Plotting the apparent soil
porosity against Dm or dwe found that both increased with respect to porosity,
being logarithmic for Dm and linear for d. The ratio (d–
Dm) can characterize each of
the horizons considered in this study when the mass dimension was estimated not
using only the smallest length scales, which is highly sensitive to the threshold
criteria.
REFERENCES
[1] Tarquis, A.M., R.J. Heck, J.B. Grau, J. Fabregat, M.E. Sanchez and J.M. Antón. 2008.
Influence of Thresholding in Mass and Entropy Dimension of 3-D Soil Images. Nonlin. Proc.
Geophys., 15, 881–891.
[2] M.E. Sanchez, A.M. Tarquis, J. Fabregat, D. Andina, J. Jimenez, and J.W. Crawford.
Variation in spectral and mass dimension on 3D soil image processing. Geophysical Research
Abstracts, 11, EGU2009-2260, 2009.
[3] A.M. Tarquis, M.E. Sanchez; J.M. Antón; Juan Jimenez; A. Saa-Requejo; D. Andina
and J.W. Crawford. Variation in spectral and mass dimension on 3D soil image processing.
Soil Science, 177(2), 10 pp, (in press) 2012.
ACKNOWLEDGEMENTS
We thank Prof. Richard Heck for his collaboration and image acquisition. Dr. K. Haskard
advice in the ANOVA analysis is greatly appreciated. First author has a stage at
SIMBIOS thanks to MEC under project PR2007-0437. This research has been partially
supported by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no.
AGL2010-21501/AGR. |
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