4
GLCM FEATURES FOR DIFFERENT COAL
LITHOTYPES
In order to control rib failures in underground coal mines,
NIOSH is developing a stability analysis and support
design tool for coal pillar ribs. Rib photos have been taken
by NIOSH researchers during the extensive field trips for
rib surveys in underground coal mines in the U.S. Most
of the ribs are either weathered or covered with dust and
sealant, which significantly affects the color and textures.
In order to obtain the representative features, the areas with
fresh surface within the rib photos were selected for this
study. The fresh surfaces are not newly mined coal pillar
ribs but are fresh failure surfaces after rib spalling. Two rib
fresh surfaces were selected, one for BC and the other one
for banded bright coal (BBC). For each selected rib fresh
surface, multiple photos were taken with different camera
settings.
The photos for BC were taken in an underground coal
mine in Virginia. As an example, the cropped image taken
under a specific camera setting is shown in Figure 2 (a). The
width and height of the image are 1,773 and 1,349 pix-
els, respectively, and the width of covered area is 330 mm
(13 inches). The fresh surface for BBC was selected in
an underground coal mine in Illinois. An example of the
cropped image is shown in Figure 2(b), which was taken
with the same camera settings as the BC image. The width
and height of the cropped image are 4,424 and 1,761,
respectively, and the width of the covered area is 914 mm
(36 inches).
Figure 1. An example application of GLCM to classify coal and shale on a rib image