digital close range photogrammetry of soil excavation surfaces jared m. shaffer gims specialist ohio...
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Digital Close Range Photogrammetry of Soil Excavation Surfaces
Jared M. Shaffer
GIMS Specialist
Ohio Department of Agriculture
2015 Ohio GIS ConferenceSeptember 21 - 23, 2015 | Hyatt Regency Columbus| Columbus, Ohio
Digital Close Range Photogrammetry of Soil Excavation Surfaces for 3D Modeling
Jared M. Shaffer
GIMS Specialist
Ohio Department of Agriculture
2015 Ohio GIS ConferenceSeptember 21 - 23, 2015 | Hyatt Regency Columbus| Columbus, Ohio
Brian K. Slater, PhDAssistant Director and Associate Professor The Ohio State University, School of
Environment and Natural Resources
Tania D. Burgos-HernándezPhD StudentThe Ohio State University, School of
Environment and Natural Resources
Digital Close Range Photogrammetry• Photogrammetry
▫ “The art and science of obtaining precise mathematical measurements and three-dimensional (3D) data from two or more photographs”
• Digital Photogrammetry▫ Expanded EM spectrum, new operational scales▫ 3D Measurement and Modeling (3DMM) software
• Close Range Photogrammetry (CRP)▫ Object to sensor distance of < 300m
DCRP Approaches for Soil Images• Digital photogrammetry can be significantly simpler
and less expensive than laser scanning, and the quality of 3D models created has been shown to be comparable (Aguilar et al, 2009)
• Stereography▫ Multiple overlapping photos are taken at different
angles or orientations▫ 3D synthesized from parallax▫ depth relationships in the images can be accessed via
triangulation• Focus Stacking (Extended Depth of Field)
▫ multiple photographs taken at different focal distances from an object
▫ 3D synthesized from depth of field (using focal acuity contrasts between photographs)
Focus Stacking
Successive images are focused on object planes at different distances from image sensor, and exhibit narrow zones of in-focus pixels. Software identifies in-focus pixels from multiple images and combines them to reconstruct a fully focused image. 3D surface can be generated.
Berejnov, 2009
Some Applications
•Archeology•Architecture•Forensics•Stockpiles•Example application:
▫Soil excavation volume and bulk density
Bulk Density
• Fundamental soil physical property
• Proxy for other properties that may be less easily estimated (e.g. pore space)
• Commonly used to convert gravimetric measurements and concentrations to volumetric or areal quantities (e.g. soil carbon)
• Can be challenging to measure in some soils
Objective
•Compare bulk density measurements from soil pit horizons using conventional methods (core and clod), and from DCRP derived soil volume
•Site: Miamian silt loam, Madison Co., Ohio
DCRP Workflow• Photography
▫ Equipment: 35mm DSLR camera 24, 50, 60 mm macro
lenses Tripod and slider bar for
positioning
▫ Sequential overlapping photographs
DCRP Workflow
•Processing▫Software: EOS Systems Inc. Photomodeler▫Camera calibration▫DSM Model building 2-30 minutes▫Scaling & Editing▫Volume measurement
•To do▫More soils and situations, uncertainty▫Before and after models▫Measurements from focus-stacked models▫Printing
•Conclusions▫DCRP is a useful technique for soil profile
visualization▫Inexpensive alternative to laser scanning
for volume and shape-based measurements
Thank You
•Questions?
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