How to measure a suite of photos taken from one sample?

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Lars-Ake
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How to measure a suite of photos taken from one sample?

Postby Lars-Ake » 21 May 2010, 21:07

There are two basic ways to do this with CooRecorder and CDendro:

1. Copy all the photos together - without any careful overlaping! - and measure from the big photo.
Where you have to "jump" to the next photo in the suite, use a "double-point", as described at
http://www.cybis.se/forfun/dendro/helpcoorecorder7/meacrack/index.htm
Drawback 1: This case requires that you have the same resolution on all your photos.
Drawback 2: The resulting image might become so big that CooRecorder cannot open it.

2. Measure each photo as a separate .pos file which you "synchronize" with CDendro and put all the .pos-files into a collection. From this you create a mean value ring width file for your whole sample.

This alternative allows you to have different resolution for different sections (photos) of the sample.

To help the synchronization, it is best to identify and mark some "synchronization points" which are visible on more than one picture. When such a point is measured in CooRecorder, I recommend you to attach a "Point-label" (e.g. a letter like "K") to the point. When you try to synchronize the .pos files in CDendro, these labels will be visible in the curve diagram so you can see that they are positioned at the same year to make the pos-files overlap correctly.

Colin Bergeron
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Re: How to measure a suite of photos taken from one sample?

Postby Colin Bergeron » 27 Nov 2010, 00:27

The second option works well for me especially that I do have some sections scanned to higher resolution. There are also minor drawbacks. For example, the point labels are lost when creating a mean value curve. Also, when you match the 2 parts and no ring overlap (stop measuring at one ring and start at the next one), it creates a zero ring in the normalized curve of the mean value. It disappears after you save the .wid file and reopen it. Would it be a better strategy to have some overlapping measured rings when matching the 2 parts of the same radius :?:
Colin

Lars-Ake
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Re: How to measure a suite of photos taken from one sample?

Postby Lars-Ake » 27 Nov 2010, 01:08

Colin Bergeron wrote:The second option works well for me especially that I do have some sections scanned to higher resolution. There are also minor drawbacks. For example, the point labels are lost when creating a mean value curve. Also, when you match the 2 parts and no ring overlap (stop measuring at one ring and start at the next one), it creates a zero ring in the normalized curve of the mean value. It disappears after you save the .wid file and reopen it. Would it be a better strategy to have some overlapping measured rings when matching the 2 parts of the same radius :?:


I see no reason why not to make the measurements overlap each other! I usually do it that way. Is there any drawback?

The other question, on lost labels from .pos-files when converting to a mean value curve:
That could be fixed by saving them in some new format for the .wid-files, but that does not solve the problem when putting the .wid-files into a collection.
These labels can indeed be exported from a collection into a tabular format text file but only if the collection is based on .pos-files!
To make ring-labels (point-labels) appear in .rwl or .fh files we have to start using special formatted comments that register this ring specific information.
In a future these problems might be solved with the DCCD xml-format - though 1. we do not yet have support for that in CooRecorder/CDendro
and 2. we probably nevertheless need a standardization of that xml data to take care of such labels.

The only quick solution to handle the case of several .pos-files for one radius is probably to extend the .wid-file format.
Though is this really such a requested solution that I should fix it?
Then, question is whether somebody has written another program that reads CDendro .wid-files and would be influenced by such a change?
/Lars-Åke

Colin Bergeron
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Re: How to measure a suite of photos taken from one sample?

Postby Colin Bergeron » 27 Nov 2010, 01:51

Overlapping measurements seems like the way to go, it does not create the zero ring in the normalized values as opposed to no overlapping measurement. I am trying to work out a way to keep my fire years labels together with the whole radius so it pops out next time I open to compare it to other radii.
Colin

Lars-Ake
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Re: How to measure a suite of photos taken from one sample?

Postby Lars-Ake » 06 Dec 2010, 23:33

Collecting and exporting CooRecorder point-labels
Some users add "pointLabels" when measuring in CooRecorder. Typical marks are for a fire scar or a sudden decrease of growth rate. Collections with such synchronized .pos-files can be saved in the .fil format of CDendro. The labels can be exported with the command "Write Coordinate LABELS in Tabular format" which might line up marks at certain year numbers.
Now, problem was with multi-radii samples where the labels of one stem were spread over more than one .pos-file.

With the new test/development version of CDendro (released for test today) you can first Create a Mean value sample out of the members of a "same stem collection" and save that file in the CDendro .wid format and then add it to the multi-stem collection.

All your pointLabels will go into the .wid-file together with the ring widths. If you open the .wid file in CDendro you will see your labels. Note that you have to use the Settings command and enable "Save ring width and point labels data as" to get this optional new write command visible in the Samples menu.


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