1. The Smartphone D-tape A Lightening Talk presented by: Dr. John A. Kershaw, Jr. Professor of Forest Mensuration Faculty of Forestry & EM, University of New Brunswick

2. 1813

3. 1913

4. 1963

5. 2013

6. There are some alternatives

7. Close-range photogrammetric approaches Stereo photographs with known center-point distances Vanishing Point Horizon with laser pointer Dual lasers with known laser distance An alternative

9. Criteria Fast Accurate Repeatable Cheap Automated

10. Smartphone Decent high resolution camera App development easy and cheaply distributed Compact, and since most everyone has one, not an additional piece of equipment

11. Goal Take two photos, with random phone movement (distance, rotation and yawl) From these two photos determine: Camera shift {X,Y,Z} coordinates Estimate DBH

12. Epipolar Geometry

13. Two photos

14. The “Fundamental” Matrix

15. Coincident Photos Add the DBH line, map the pixels from one photo to the other

16. DBH Estimate OLS solution to the Fundamental Equation Camera Focal Length and Camera Aspect Ratio used to convert from pixels to real world coordinates DBH estimated from 3D coordinate distances Include inclination angle for upper stem diameters (Grosenbaugh 1963)