Multi-filter analysis of infrared images from the excavation experiment in horizontally stratified rocks

This paper presents a morphological study of the low-resolution and noisy thermogram obtained in the laboratory excavation experiment on the large-scale geological model of man-made horizontally stratified rocks. The developed new image processing algorithm consists of image subtraction, median filter, low-pass alternating-morphological filter, and multi-scale morphological enhancement filter. These filters were used sequentially to process the detected infrared images. In comparison with the old algorithm for thermogram process, the excavation border with changed stress and changed brightness can be distinguished more clearly in the new thermogram sequences. The new algorithm is possible to be applied in processing other low-resolution and noisy thermogram, and the analysis results in this paper are helpful for understanding the pure elastic, the stationary frictional effect and the dynamic frictional effect at the excavation processes.

► New multiple filters was developed for processing low-resolution thermograms from excavation experiment. ► Subtraction, median and low-pass filters were used for reduction the noises and enlargement of the dynamical scope. ► Multi-scale morphological filter was used for enhancement of the thermograms. ► Excavation border and changed stresses can be distinguished more clearly in the thermograms processed. ► Results are helpful in processing low-quality thermogram and understanding rock behavior at excavation processes.