5
• Organize drone photos taken from fieldwork in fold-
ers according to location and pre and post rockfall
test flight sequences
• Start a new project in Agisoft Metashape by adding
photos from a drone flight sequence into a chunk
• Start the workflow process – align photos, go with
the preselected properties
• For rock runout distance models, take the necessary
steps to minimize error in the alignment:
– Create two markers in Agisoft Metashape on
one of the cameras (photos) on known reference
spots (2-by-2-foot X’s spray painted by NIOSH
researchers on the ground near the rockfall drop
location on the crest of the bench).
– Go to a second camera and make sure the markers
are on the same exact spot. This should adjust it for
every camera, feel free to double check.
– Go to workflow, batch process, click “Add….” For
Job Type, choose “Optimize Alignment” and apply
to all chunks. Check “Save project” after each step.
– Under the reference for each marker, check to see
if their error is less than 0.03 m. If not, repeat the
steps until the error is less than 0.03 m, if possible.
• Continue the workflow process – build dense point
cloud, choose your quality and
• Export points as a .ply file for runout/bench catch-
ment analysis in Cloud Compare software. When
exporting the points, make sure to use the Local
Coordinates (m) coordinate system. The runout/
bench catchment analysis can also be performed in
Agisoft Metashape if preferred.
The pre-rockfall test photogrammetry model is used
for reference to analyze the bench/slope configuration and
characteristics associated with geology, blasting practices,
and talus buildup at the toe. The post-rockfall test photo-
grammetry models are used for runout analysis of the syn-
thetic and local rocks from the toe of the slope if it was a
single bench test or for bench catchment analysis if it was a
full highwall test.
The video camera footage gathered by the Sony 4K
Handycam FDR-AX53 is used to analyze the behavior
of rocks traveling down the slope and how factors such as
rock size, rock shape, geology, blasting practices, and talus
buildup can affect the behavior of the rock while in motion.
Additionally, with regards to full highwall rockfall tests,
the video camera footage can be extremely useful in bench
catchment analysis, especially for the smaller sized rocks.
The thermal video camera footage gathered by the
FLIR T620 Thermal Camera is used to aid the University
of Arizona Geotechnical Center of Excellence (GCE) in
their research to detect and monitor rockfall events in sur-
face mines using existing thermal camera technology [13].
LESSONS LEARNED
Pre-Rockfall Testing
The development of synthetic rocks for each rockfall test
takes a significant amount of time and resources from the
NIOSH research team. After a couple rounds of testing
at mines within a 2-hour radius of Spokane, WA, it was
decided that the number of rocks to be developed accord-
ing to each size and shape for a single rockfall test are as
follows:
• 3-inch diameter – 50 cubes, 50 ETAG, and 50 plates
• 6-inch diameter – 40 cubes, 50 ETAG, and 40 plates
• 12-inch diameter – 12 cubes, 12 ETAG, and 20
plates
• 18-inch diameter – 8 cubes, 8 ETAG, and 10 plates
This provides a total of 340 rocks (one suite of rocks)
per rockfall test. The chosen number of rocks per rock
size was decided upon according to weight limitations of
NIOSH hauling equipment and having enough samples
Figure 3. Example of local rocks collected and spray painted
prior to rockfall testing
• Organize drone photos taken from fieldwork in fold-
ers according to location and pre and post rockfall
test flight sequences
• Start a new project in Agisoft Metashape by adding
photos from a drone flight sequence into a chunk
• Start the workflow process – align photos, go with
the preselected properties
• For rock runout distance models, take the necessary
steps to minimize error in the alignment:
– Create two markers in Agisoft Metashape on
one of the cameras (photos) on known reference
spots (2-by-2-foot X’s spray painted by NIOSH
researchers on the ground near the rockfall drop
location on the crest of the bench).
– Go to a second camera and make sure the markers
are on the same exact spot. This should adjust it for
every camera, feel free to double check.
– Go to workflow, batch process, click “Add….” For
Job Type, choose “Optimize Alignment” and apply
to all chunks. Check “Save project” after each step.
– Under the reference for each marker, check to see
if their error is less than 0.03 m. If not, repeat the
steps until the error is less than 0.03 m, if possible.
• Continue the workflow process – build dense point
cloud, choose your quality and
• Export points as a .ply file for runout/bench catch-
ment analysis in Cloud Compare software. When
exporting the points, make sure to use the Local
Coordinates (m) coordinate system. The runout/
bench catchment analysis can also be performed in
Agisoft Metashape if preferred.
The pre-rockfall test photogrammetry model is used
for reference to analyze the bench/slope configuration and
characteristics associated with geology, blasting practices,
and talus buildup at the toe. The post-rockfall test photo-
grammetry models are used for runout analysis of the syn-
thetic and local rocks from the toe of the slope if it was a
single bench test or for bench catchment analysis if it was a
full highwall test.
The video camera footage gathered by the Sony 4K
Handycam FDR-AX53 is used to analyze the behavior
of rocks traveling down the slope and how factors such as
rock size, rock shape, geology, blasting practices, and talus
buildup can affect the behavior of the rock while in motion.
Additionally, with regards to full highwall rockfall tests,
the video camera footage can be extremely useful in bench
catchment analysis, especially for the smaller sized rocks.
The thermal video camera footage gathered by the
FLIR T620 Thermal Camera is used to aid the University
of Arizona Geotechnical Center of Excellence (GCE) in
their research to detect and monitor rockfall events in sur-
face mines using existing thermal camera technology [13].
LESSONS LEARNED
Pre-Rockfall Testing
The development of synthetic rocks for each rockfall test
takes a significant amount of time and resources from the
NIOSH research team. After a couple rounds of testing
at mines within a 2-hour radius of Spokane, WA, it was
decided that the number of rocks to be developed accord-
ing to each size and shape for a single rockfall test are as
follows:
• 3-inch diameter – 50 cubes, 50 ETAG, and 50 plates
• 6-inch diameter – 40 cubes, 50 ETAG, and 40 plates
• 12-inch diameter – 12 cubes, 12 ETAG, and 20
plates
• 18-inch diameter – 8 cubes, 8 ETAG, and 10 plates
This provides a total of 340 rocks (one suite of rocks)
per rockfall test. The chosen number of rocks per rock
size was decided upon according to weight limitations of
NIOSH hauling equipment and having enough samples
Figure 3. Example of local rocks collected and spray painted
prior to rockfall testing