6
wall, the distance/location of one stitched frame from the
borehole end can be approximated from the accumulative
offset value from the first video frame, and the horizontal
and vertical movement of this frame can be obtained from
its offset values. In this way, the horizontal and vertical
movement of the video frames, estimated from the corre-
sponding offset values in pixels, can be marked at differ-
ent locations along the scoped borehole, corresponding to
frame location. This can help visualize the borescope move-
ment when scoping a borehole where smooth movements
with constant speed are expected. The borescope movement
in vertical and horizontal directions for the three recorded
borehole videos is presented in Figure 8.
It should be noted in Figure 8 that there are break
points, representing the locations where the image stitch-
ing process failed. If the borehole video cannot be stitched
together, multiple borehole image segments would be
obtained with gaps, as can be seen in Figure 8, with a seg-
ment of the stitched borehole images with 4 break points.
Instead of having small offset values along vertical and hori-
zontal directions, the frame that cannot be stitched to the
previous one is moved vertically to the bottom of the previ-
ous frame and is further moved down with a gap for visu-
alization purposes. Under this circumstance, the borehole
length that the panoramic borehole image covers should
be longer than the borehole depth, which can be observed
in the next section. The generated panoramic borehole
images have a height varying from 70,000 to 80,000 pixels.
The cropped image height was 250 pixels, and a gap of 10
pixels was used in this study. Compared with the image
height, the influence of the extra pixels on the averaged
pixel dimension can be negligible, and thus, even though
there are extra pixels that resulted from the failure in the
image stitching process, the borehole depth was averaged
over the panoramic image height for the following calcula-
tion of video frame location and borescope movements in
Figure 8. It must be mentioned that, due to the failure in
the image stitching process, there were large spikes in the
vertical movements in Figure 8 at the borehole locations
marked with break points. Rather than true vertical move-
ments, these are artificial movements from the image stitch-
ing process to demonstrate the break points and continue
the following stitching process. They were removed from
the plot. At the corresponding locations, break points were
used to mark the failure in the image stitching process.
In Figure 8, the positive values mean downward move-
ment in vertical direction and indicates the borescope
rotates towards the right in horizontal movement. The neg-
ative values in vertical movement indicate the borescope
moves up and left rotation in horizontal movement. It is
Figure 8. Comparisons of borescope movement during recording under three different conditions with a segment with four
break points under freshly washed condition
wall, the distance/location of one stitched frame from the
borehole end can be approximated from the accumulative
offset value from the first video frame, and the horizontal
and vertical movement of this frame can be obtained from
its offset values. In this way, the horizontal and vertical
movement of the video frames, estimated from the corre-
sponding offset values in pixels, can be marked at differ-
ent locations along the scoped borehole, corresponding to
frame location. This can help visualize the borescope move-
ment when scoping a borehole where smooth movements
with constant speed are expected. The borescope movement
in vertical and horizontal directions for the three recorded
borehole videos is presented in Figure 8.
It should be noted in Figure 8 that there are break
points, representing the locations where the image stitch-
ing process failed. If the borehole video cannot be stitched
together, multiple borehole image segments would be
obtained with gaps, as can be seen in Figure 8, with a seg-
ment of the stitched borehole images with 4 break points.
Instead of having small offset values along vertical and hori-
zontal directions, the frame that cannot be stitched to the
previous one is moved vertically to the bottom of the previ-
ous frame and is further moved down with a gap for visu-
alization purposes. Under this circumstance, the borehole
length that the panoramic borehole image covers should
be longer than the borehole depth, which can be observed
in the next section. The generated panoramic borehole
images have a height varying from 70,000 to 80,000 pixels.
The cropped image height was 250 pixels, and a gap of 10
pixels was used in this study. Compared with the image
height, the influence of the extra pixels on the averaged
pixel dimension can be negligible, and thus, even though
there are extra pixels that resulted from the failure in the
image stitching process, the borehole depth was averaged
over the panoramic image height for the following calcula-
tion of video frame location and borescope movements in
Figure 8. It must be mentioned that, due to the failure in
the image stitching process, there were large spikes in the
vertical movements in Figure 8 at the borehole locations
marked with break points. Rather than true vertical move-
ments, these are artificial movements from the image stitch-
ing process to demonstrate the break points and continue
the following stitching process. They were removed from
the plot. At the corresponding locations, break points were
used to mark the failure in the image stitching process.
In Figure 8, the positive values mean downward move-
ment in vertical direction and indicates the borescope
rotates towards the right in horizontal movement. The neg-
ative values in vertical movement indicate the borescope
moves up and left rotation in horizontal movement. It is
Figure 8. Comparisons of borescope movement during recording under three different conditions with a segment with four
break points under freshly washed condition