Regularity Analysis of Airborne Natural Gamma Ray Data Measured in the Hoggar Area (Algeria) - Advances in Data, Methods, Models and Their Applications in Geoscience - page 100

Moreover, the estimated Hölder functions obtained from the three types of measurements
present very close values. Again, we confirm that the fractal properties of the raw data are
not modified by both pre-processing operations. The implementation of the different 2D-
interpolation algorithms illustrates that the choice of the interpolation algorithm has a very
slight effect on the estimated H value. An important result to be noted: the spectrometric
corrections are not necessary for a fractal analysis which can be carried out directly on the
raw measurements. By doing so, the stochastic component of the measurements is kept
intact.
6. Local regularity analysis of airborne spectrometric data
In this section, we establish local two-dimensional regularity maps, from the interpolated
raw GR data measured in the three channels: K, Th and U, using a wavelet-based algorithm
via the two-dimensional Multiple Filter Technique (2D MFT). We obtained the latter
technique by generalizing the mono-dimensional version (Dziewonski et al. , 1969; Li, 1997)
to the 2D-case (Gaci, 2011).
6.1 Spectrometric data interpolation
Considering the limitations of the computer's processing capacity, we consider the GR
measurements recorded, in the K, Th and U channels, over the zone whose geographical
coordinates are defined by: longitude: 3° 13' 58''- 6°59' 26'' E, and latitude: 20° 27' 35''-25°
06' 37'' N.
The 2D-interpolation of the raw spectrometric data is performed owing to the kriging
algorithm. The interpolated GR grids data related to the K, Th and U channels are illustrated
respectively by figures 4, 5 and 6.
Fig. 4. Interpolated Gamma Ray measurements (in cps) related to the K channel .