1. Digital Close Range Photogrammetry of Soil Excavation Surfaces
Jared M. Shaffer
GIMS Specialist
Ohio Department of Agriculture
2015 Ohio GIS Conference
September , 2015 | Hyatt Regency Columbus| Columbus, Ohio

2. Digital Close Range Photogrammetry of
Soil Excavation Surfaces for 3D Modeling
Jared M. Shaffer
GIMS Specialist
Ohio Department of Agriculture
2015 Ohio GIS Conference
September , 2015 | Hyatt Regency Columbus| Columbus, Ohio

3. Tania D. Burgos-Hernández
Brian K. Slater, PhD
Assistant Director and Associate Professor
The Ohio State University, School of Environment and Natural Resources
Tania D. Burgos-Hernández
PhD Student

4. Digital Close Range 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

5. 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)

6. Stereography
Object points appear at slightly different positions on multiple photographs (image planes). Software is used to triangulate bundles of focused observation rays to create 3D point clouds to represent object surfaces and shapes.
Aguilar et al., 2005

7. Stereography – Dense Surface Modeling
For accurate 3D models (e.g. Dense Surface Modeling), camera is moved parallel to mean object surface, and adjacent photographs should have at least 60% overlap
Matthews, 2008

8. 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

10. Some Applications Archeology Architecture Forensics Stockpiles
Example application:
Soil excavation volume and bulk density

11. 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

13. 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

14. DCRP Workflow Photography Equipment:
35mm DSLR camera
24, 50, 60 mm macro lenses
Tripod and slider bar for positioning
Sequential overlapping photographs

18. DCRP Workflow Processing Software: EOS Systems Inc. Photomodeler
Camera calibration
DSM Model building 2-30 minutes
Scaling & Editing
Volume measurement

25. To do Conclusions 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

26. Thank You
Questions?