Generating panoramic unfolded image from borehole video acquired through APBT

In geological engineering, geological structure detection is crucial to the engineering design and implementation. One of the most commonly used method is to acquire the borehole videos by Axial View Panoramic Borehole Televiewer (APBT). However this method analyzes the borehole information by video playback or video snapshot, only providing a qualitative description for borehole, but cannot obtain a unfolded image to make quantitative analysis. In this paper, we propose a novel method to generate a complete borehole unfolded image from the video taken by APBT. Firstly, a center location method based on circularity is proposed to automatically locate the center of annular borehole images obtained from the borehole video. Then the annular borehole image sequences are unfolded into the borehole unfolded image sequences by the Rubber sheet model (RSM) combined with interpolation algorithm. Finally, the unfolded image sequences are fused into an entire panoramic unfolded image based on improved gray-scale projection registration algorithm. The experimental results shows that, with our proposed method, panoramic unfolded images from borehole videos with satisfying visual quality to analyze the geological conditions can be obtained efficiently.