CooRecorder: Check against a reference curve during measurement!

Last update 3 March 2014.
Fig 1
With CooRecorder you can have your current ring width measurement curve and a reference curve visible while you set out points for ring width borders on your scanned image. This tool will likely be more useful for those who work on short and recent wood cores, taken from living trees. In such cases the sampling year is known and the successively achieved ring width measurements can be directly compared to the reference curve. Any errors will then quickly become visible.

Fig 2
To make CooRecorder show your ring width curves, use the menu command "File/Enable ring width curve display". CooRecorder will open a frame for display of the curves at the bottom of the screen and prompt you for a .wid file (created in CDendro) or a .pos file containing your reference curve.

Using a .pos-file means that you can set your first measured radius (a .pos-file) as your reference and then start measuring your second radius with the first one as a support.


Fig 3
Your reference will be shown as a blue ring-width curve and a black normalized curve based on the P2Yrs method (ref 1).

Your current measurements (not yet saved) or your current .pos file will be plotted on top of your reference curve as a green ring width curve and a red curve of normalized data, i.e. all curves are shown as in CDendro.

To synchronize the curves, click on the button to the right of the "Offset:-box" above the curves. Current correlation coefficient, T-value and overlap are then shown as text on top of that button.

At the bottom of the curve diagram you will find correlation coefficients plotted every 10th year and calculated from 20 years long successively overlapping segments.

To change the offset between your measurement curve and the reference (i.e. to shift your curve along the reference curve) either use the small "arrow-buttons" at the sides of the "Offset:-box" or use the arrow keys of your keyboard like in CDendro (then first click on the curve diagram to make it focused before pressing an arrow button). When you move the curves in relation to each other, all correlation values will be automatically updated.

If you click on the curve, the corresponding point within the upper picture will be "selected", i.e. made bold - see point 9 in the picture above. Correspondingly: If you select one of your points in the upper diagram, a vertical short green line will be drawn across the ring width curve at the corresponding position. The ring width of that point is shown in the textbox to the left of the "Offset:-box".

If your image has its youngest ring width to the left (instead of to the right as shown above) you may prefer to have your curves displayed correspondingly. In that case, click the "<--Times-->" button to make the curves plotted the other way.


Fig 4
If you click the "Show Selected" button and keep the mouse button down, circles will be shown around the selected point both within the image and on the curves. If you do this while either the point on the image or the point on the curve is not visible, the image or the curve will be moved so that you see the selected point.

If you click a point of the curves where the corresponding point on the image is not visible (or vice versa), the image will be automatically moved to make the point come within sight. If this mechanism of automatic image or curve shifting is felt too "pushy" it can be turned off by Settings/Other settings/Enable automatic image and curvescrolling.

Fig 5
Heavy detrend. When the oldest rings of a tree are wide and all the young rings are narrow, the younger end of the ring width curve might look almost flat. To compensate for this, you can check the "Heavy detrend" checkbox for the corresponding curve. Heavy detrend implies that a current ring width has been divided by a mean value of the 24 surrounding rings for that current ring. You can see the effect of this detrend operation by comparing the green curves of Fig 3 and Fig 4 above. In Fig 4 the green curve looks less flat in its young tail!

Making big change of offset by dating with "Y" command.
If you need to move your curve a big step along the reference, then use the menu command "More/Set Year (Y) of selected point or else of Ring 0" to position your curve. With a certain point selected you can then easily position that point at a suitable year number on the reference.

Please note: The selected point gets the year number! If there is no point selected, the outermost point gets the year number. I.e. if you by accident have point number 50 selected and enters the year number "2010" with the Y-command, then the outermost point of your series will be dated to "2060".


Hiding the curve diagram with Ctrl-Tab
If you are working with a small screen, the curve diagram might sometimes block your view. You can then easily turn off the curve diagram with the menu command "Enable ring width curve display (Ctrl-tab)". I.e. by just pressing Ctrl-tab you can turn off or turn on your curve diagram!
Reference:
1. P2Yrs, Proportion of last two years growth, see CDendro Settings Options.. and Settings Toolbox.. or Cybis Dendro Wiki on Normalization


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