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For Tree-Ring, Stem, Wood Density Analysis & Measurement
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R. Guay, J.L. Arseneault, Régent Instruments Inc., R. Gagnon and H, Morin, Université du Québec in Chicoutimi, Canada In collaboration with: F.H. Schweingruber, WSLFNP, Switzerland |
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| A new mean of measuring tree-ring density from an X-ray film of a thin wood slice is presented. Instead of using a mechanical slot for measuring the quantity of light passing through the film, a software programmable slot, hence virtual, is used. First, the wood sample is prepared as a thin wood slice according to the Dr. Schweingruber method. Then an image of the X-ray film is digitized on an optical scanner with a transparency attachment. Then a path on which to measure density is drawn by the operator in the image. This path is used by the system to automatically find each ring position and orientation. The next step is the density calibration. It is performed by comparing the image intensity values with those on a known density step wedge which has been X-rayed with the wood sample. After that, the system creates a slot which will scan the image on the path created by the operator and record density of rings. This slot adapt itself such as it has an angle tangent to the tree rings when the density is computed. The shape, size and orientation of the slot can be modified at anytime along the path. Using an optical scanner instead of a video camera has many advantages as was shown in an earlier paper (Guay et al. The Forestry Chronicle Feb, 92). Lighting distribution problems are eliminated by this movement of the light in synchronization with the scanner's linear camera. Calibration is also done to compensate for differences between each camera elements. The approach presented here is fast and flexible because no mechanical parts are involved in the wood density measurement. Precision is also good because wood density is always measured along the ring's tangent. This method is also very affordable due to the abundance of low-cost scanners. And finally, the equipment can be used for other applications like measuring tree ring width or studying leaf and stem morphology. |
| To learn more about WinDENDRO click the following links or you can download our WinDENDRO brochure (1.4 MB). |
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Last revision: March 6, 2007