Photogrammetric Monitoring of Rock Mass Behavior in DeepVein MiningDonovan Benton, Mining EngineerStephen Iverson, Mining EngineerJeffrey Johnson, Mining EngineerLewis Martin, Research Mechanical Engineer

NIOSH, Office of Mine Safety and Health ResearchSpokane, WA

Outline

• Field photogrammetry system• Lab photogrammetry system• Measurement verification

FieldLab

Lab verification

Field Photogrammetry System

• Three auxiliary lights• Nikon D80 camera• Sigma 10mm-20mm lens• Tripod• Survey control points

Simple field setup

• Camera spacing• Distance to face• Pixel density• Control points or scale

D

D/5 to D/8

plan view

Photogrammetry Reconstruction

FaultTrace

• Three pairs merged

Quality Improvement

January 2013--camera handheld using flash

May 2013--Tripod, auxiliary lights, timed exposure

Closer Look

Photogrammetry Software

• Shapemetrix3D—3GSM• 3DM Analyst—Adam Technology• PhotoModeler Scanner—Eos Systems Inc.• Bundler/PMVS2—Open source software

• Sirovision—CAE Mining

PMVS2--Patch-based Multi-view Stereo Software

Alternative

Changing Ground Conditions

Unity Software Visualization

• photogrammetric monitoring of fault exposures to fully characterize observable slip

Lab Photogrammetry System

Camera type Nikon D800 digital SLR

Lens Sigma 20 mm

Horizontal field of view

84 degrees

Vertical field of view 61 degrees

Effective image pixels 36.3 million

Pixel resolution at 5 m 0.1 cm by 0.1 cm

High Energy High Displacement Test (HEHD)

Stripping Panel Forms

Mount and Torque Panels

Panel Test

Panel Test(1 frame per second)

Point Cloud Reconstruction

Measurement Verification

Accuracy Results

Linear measure

Volume measure

Absolute and Average Error

Measurement Verification Summary

Field system•Average linear error was +/- 0.03 inches.

Lab system•Average linear error was +/- 0.05 inches.•Average volume error was +- 1.76 percent.

Photogrammetry Conclusions

• The field system is a fast and relatively inexpensive way to document site conditions.

• The lab system using dual cameras allows documentation for fast moving experiments.

• Linear and volumetric measures are within acceptable limits for determining ground movement.

Questions?