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Density analysis
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WinDENDRO is available with or without density analysis capability. When the latter is ordered, an additional menu which contains density related commands, is added to WinDENDRO's regular menus.
Publications have demonstrated that ring density is more related to climate and wood quality than ring width alone. The principles behind WinDENDRO's density analyses are well known and have been applied for many years in tree ring analysis. Moreover, Regent has added innovative concepts and others are currently being developed. |
| Different methods can be applied to perform density analysis in WinDENDRO |
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The conventional film-based method
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This method is the oldest and most widely used method for tree ring density analysis by dendrochronologists. It is well documented in Dr. Schweingruber book
Basic and Applications of Dendrochronology.
Wood samples are cut into thin slices (1 to 2 mm thick), brought to a predetermined humidity level and exposed to x-rays over a film. The films are then calibrated and analyzed through an analog densitometer. These are electromechanical devices that read the intensity of light passing through the x-ray film in a slit of fixed size that is moved along the film.
In WinDENDRO, the analog densitometer is replaced by a digital method that consists of scanning the x-ray film and then measuring light that passes through a virtual slit scanned over the image. Unlike the analog densitometer, parameters such as slit size (and eventually shape) can easily be changed. When computing density, WinDENDRO automatically sets the slit angle tangent to the ring boundary in order to produce accurate measurements. The slit angle linearly changes its orientation gradually between rings so that it is tangent to all rings boundaries. The operator can interactively override the slit angle estimated by WinDENDRO. |
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WinDENDRO displays the image of the analyzed sample and the computed density profile side by side.
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| The reflected-light method |
One major advantage of the reflected-light method is that it does not require costly radiation equipment.
This method does not produce true density measurements but estimates density based on the assumption that the color of the wood is related to its density. When the wood surface is carefully prepared, it makes sense to think that the reflected light profile (red line on the right) can be calibrated to procure absolute density measurements. This calibration is not simple, however, and we are not aware of a successful calibration method. Because of this, the reflected light profile is used for relative density measurements instead.
Along ring paths, WinDENDRO measures the amount of reflected light from the piece of wood and produces these values along with measurements made on them (see below). |
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The reflected-light method requires a good understanding of its limitations before use. For background information, please refer to:
Reflected-Light Image Analysis of Conifer Tree Rings for Dendrochronological Research, P. R. Sheppard, Ph.D. Thesis 1995, Department of Geosciences, University of Arizona.
Wood Density Measurement: Comparison of X-Ray, Photometric, and Morphometric Methods. Department of Forest Sciences, The University of British Columbia, 270-2357 Main Mall, Vancouver, B.C. V6T 1Z4, Canada. |
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The film-less digital x-ray imaging method
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| It is possible to use the newest digital x-ray cameras or scanners to acquire x-ray images of pieces of wood. With these devices, there is no film exposure or development. Once the system has been purchased, there is no operating cost it (except for operator time and regular maintenance). The pieces of wood still have to be prepared as described above.
Density is measured in WinDENDRO from these images exactly as it is from digitized films. All software functions required to analyze such images are already present in WinDENDRO Density.
Regent Instruments currently does not sell digital x-ray cameras or scanners but we may sell them in the future. |
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| Low resolution x-ray image obtained with experimental direct x-ray camera |
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| Multiple density measurements can be saved on a ring or pixel basis |
Available per ring
- Ring width
- Earlywood and latewood width (in mm or percentage of ring width)
- Ring maximum density
- Ring minimum density
- Ring mean density
- Earlywood mean density
- Latewood mean density
- Ring boundary tangent orientation
Available per pixel along a ring path
- Pixel density or light intensity (calibrated or not)
- Slit orientation
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Ring width, earlywood/latewood width and density (min, max and average values)
can be measured on X-ray films of pieces of wood.
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Ring width, earlywood/latewood width and intensity of reflected light (min, max and average values)
can be measured directly on pieces of wood.
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| To learn more about WinDENDRO click the following links or you can download our WinDENDRO brochure (1.4 MB). |
