A Simple Optical Dendrometer based on a Digital Camera and

Visible Laser Pointer

John A. Kershaw, Jr.Western Mensurationists Meeting

Vancouver, WA

June 21-23, 2009

(The Art of Kamera Sutra)

Panoramic Tripod MountPanoramic Tripod Mount

Stitching ProcessStitching Process

• Used software called panorama factory– http://www.panoramafactory.com/

• Automates the process• Corrects geometrical lens errors

Panoramic Photo PlotsPanoramic Photo Plots

Enhanced Photo PointsEnhanced Photo Points

• Tagged trees– Indexes trees in the image– Width of the tag is a constant

• ARTaghttp://www.cv.iit.nrc.ca/

research/ar/artag/

Previous commentsPrevious comments

• If you have to “tag” each tree, why not simply measure it?

• Seems to be substituting office time for field time?

NSERC Discovery GrantNSERC Discovery Grant• Go from “off-the-shelf” technology to

dedicated camera-field data collector system• Explore advantages/disadvantages of tagging

system and possible alternatives– Stereo Panoramic Photos– 360/180 hemisphere photos– Image Segmentation– Hidden Tree Identification

• Nagging problem of determining scale with a vanishing point horizon

Stereo PanoramasStereo Panoramas

360/180 Panoramas360/180 Panoramas (Mercator Projection) (Mercator Projection)

An innocent startAn innocent start

A Distance functionA Distance function

Too Sensitive to Camera PlaneToo Sensitive to Camera Plane

Dual Laser SetupDual Laser Setup

Canon SD430 – 5.0MP

Canon SD990 – 15.0MP

Canon 5D – 22.0MP

A New Distance FunctionA New Distance Function

DBH Resolution (cm/pixel)DBH Resolution (cm/pixel)

Quick Test on 4 Trees by 5 DistancesQuick Test on 4 Trees by 5 Distances(Canon 5D)(Canon 5D)

Predicted Distance vs Observed Distance Predicted DBH versus Observed DBH

Upper Stem DiametersUpper Stem Diameters

Automating the Process (100% laser)Automating the Process (100% laser)

Automating the Process (20% laser)Automating the Process (20% laser)

Full Panorama PlotFull Panorama Plot

Next StepsNext Steps

• Stabilize Laser Mounts• Test on Upper Stem Diameters• Automate Process• Build Image Analysis System on SD990

Questions?Questions?