Lerma, Jose Luis
The texture filtering generated the texture images to be used in conjunction of the four spectral bands. In fact, only the
most representative parameters (for these monument) were selected for the red spectral band applying the GLCM, the
mean and the homogeneity. In Fig. 2a appears the homogeneity image for a window of 3x3, whereas in Fig. 2b and 2c
appear the mean and homogeneity images for a window of 50x50. Finally, the whole set of seven images was extracted
in order to have the same physical size (resolution).
(b)
Figure 2. Textural images: (a) homogeneity (kernel 3x3), (b) mean (kernel 50x50), (c) homogeneity (kernel 50x50)
4 SPECTRAL AND TEXTURAL CLASSIFICATIONS. RESULTS
The informational classes used for the classification were defined in the selection process and proved to be
distinguishable. Three sets of extracted images were classified by means of the standard supervised rule of maximum
likelihood. All the classified images were evaluated by means of visual inspection in the field, and qualitatively
analyzed. The first set was only integrated by the visible bands; the result is shown in Fig. 3a. The second set was
integrated by the visible bands and the near-infrared band; the result appears in Fig. 3b. The last set used the whole set,
the three visible bands, the near-infrared band and the three textural bands; the result appears in Fig. 3c.
@ TT Ee E t i NC:
Figure 3. Classified images: (a) spectrally (G,B,R bands), (b) spectrally (G,B,R,IR bands),
(c) spectrally (G,B,R,IR bands) and texturally (3 bands, Fig. 2)
The visible spectrally classified image, Fig. 3a, shows only one spectral class properly recognized, clean cement mortar.
Most of the other classes have too many defect or excess errors. For example, flaking is neither well placed nor well
distributed; polished limestone is rather confused, mainly over the other kind of limestones, clean and dirty; dark
cement mortar offers flooding over washed limestone. On the other hand, washed limestone only fits the area and
follows the traces; and finally, dark limestone seems well-classified although it has some expansion over polished
limestone.
Regarding the second classified image, Fig. 3b, there is a better discrimination between cement mortar-limestone, as
well as among flaking—washed & washed limestones. Unfortunately, this classification still has got a general confusion
among polished limestone and washed & washed limestones.
482 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000.
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