Photo measuring

General discussions of measurement techniques and the results of testing of techniques and equipment.

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#1)  Photo measuring

Postby dbhguru » Wed Jan 10, 2018 10:51 am

Ents,

  Don Bertolette and I are working on an appendix to the American Forests tree-measuring guidelines that will deal with taking measurements from photographs. We have a little of this in the current guidelines, but want to go further. The attachment shows where we are now. Any ideas, suggestions would be appreciated. Current tests have all been done with my iPhone 6+. I'll soon perform some tests with my Cannon digital camera, but I'm a real novice with digital cameras. I don't even know the questions to ask. Still, the results to date with the iPhone camera have been extremely impressive. I'm usually within +/- an inch of the actual target size, often within half an inch. The attachment  explains how the photographic analysis is performed.

Bob
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Oblique Photo Measurements 9.xlsx
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Robert T. Leverett
Co-founder and Executive Director
Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
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#2)  Re: Photo measuring

Postby Larry Tucei » Wed Jan 10, 2018 11:43 am

Hi Bob-   This is some cool stuff and I know how much work you guys must have put in on this. I've used the Trupulse 360 for Dia. on a few trees on Missing Line function with great results.  Larry
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#3)  Re: Photo measuring

Postby dbhguru » Sun Jan 14, 2018 4:43 pm

Ents,

   I'm ready to draft an Appendix to the AF guidelines on photo measuring. I've conducted many tests, and with one testing session gone astray, continue getting excellent results. The attachment brings it all together. The big question is whether or not the photo method can play a useful role in measuring tree dimensions for at least some. It was partially conceived to provide certifiers with an offsite tool to check on the dimensions reported for nominations. However, to be of real value, the photo method has to be carried out according to the instructions in the attachment. No shortcuts.

Bob
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Oblique Photo Measurements 11.xlsx
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Robert T. Leverett
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#4)  Re: Photo measuring

Postby Don » Sun Jan 14, 2018 7:34 pm

Bob-
Just a quick comment to add...Ents members have heard us call for improved photo documentation. Bob's addition to the Appendix here is another reason to capture useful photos (in the case of nominations/certifications they are essential) with at least a full frontal view when possible, and enough photos of the base (to capture bark features around the trunk) and foliage/botanical characteristics to aid in the species identification.  Especially when revisits require significant commitments.
Or can't be reached at different times of the year.
-Don
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#5)  Re: Photo measuring

Postby Joe » Mon Jan 15, 2018 12:09 pm

I'm curious about this- as a guy who doesn't measure trees as y'all do- I measure trees for forestry purposes so my measurements are crude by comparison. I'm just wondering why bother measuring trees with a camera when you all do it so well with better tools?
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#6)  Re: Photo measuring

Postby Don » Mon Jan 15, 2018 4:43 pm

Joe-
I'm not sure I could imagine a scenario where you would want access to a stand, but didn't have landowner approval. But were that the case, and you were able to photograph a tree of interest, you could certainly obtain a fair amount of information about that tree, remotely. And easily within the constraints of your accuracy needs.
The uses are many, including the ability to estimate diameter, model volume...
-Don
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#7)  Re: Photo measuring

Postby dbhguru » Mon Jan 15, 2018 9:06 pm

Joe,

  Part of what drives our desire to measure trees through photographic images is to check on the dimensions submitted by nominators of champion trees. We require photographs of nominated trees, and a good thing too. Through good photos, we can identify suspect trees, and that literally can save us, because there are far too many national nominations for Cadre members to go out and re-measure every suspect. The next step is determining how far we can take photo measuring. As you see, we're presently exploring the answer.

  Here is another reason to have photo measuring as one of our tools. We like to model big trees for volume. If the modeler has a reticle-based monocular and a good hypsometer, then we have the mathematical models to accept the measurements. But not everyone has a monocular, nor plans to purchase one. Can they substitute photo modeling? The answer is probably. We're working on it.

   Do we need to push the envelope so far? Yes, if we're serious about our craft, and we are. This said, some big tree hunters long for the days when they could measure trees using Kentucky windage and game the system by submitting multi-stem clumps as single trees. Don is going to take the lead on a third appendix to address where we draw the line and then promote the concept of functional circumference.

Bob
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#8)  Re: Photo measuring

Postby Joe » Tue Jan 16, 2018 9:52 am

Bob, I just took a look at your spreadsheet. Wow! Pretty impressive. Especially the error analysis! There aren't going to be many people who have the slightest clue what you did there. I started off college as a math major but there were other things more interesting going on back then, right after "the summer of love 1967". But I still really love math.

It seems that this work is about measuring verticle sections of trees. But will it work with diameters of trees? And, what is the purpose of measuring short verticle sections of trees?

By the way, I'm now fascinated with the latest digital video cameras that can film 360 degrees. I suggest they may be useful to both field foresters and big/old tree measurers- not sure how, that's what I'm working on now- trying to figure out what to do with them.
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#9)  Re: Photo measuring

Postby Larry Tucei » Tue Jan 16, 2018 3:05 pm

Bob, Don-  Last week I was looking at the AF Champion tree listing and noticed many have no photograph. Is the next listing going to be updated and these removed until a photo is presented? I was on there to see the new Southern Magnolia in Delta NF guess what no photo- imagine that. I'm going to talk with Todd Matthews our state tree coordinator get the location, go verify the measurements and also get some photos.  Larry
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#10)  Re: Photo measuring

Postby Don » Tue Jan 16, 2018 4:45 pm

Larry-
Rest assured that Bob and I are on the issue of champions without photos.  There are a number of scenarios that explain this, but ultimately, they should all have photos (one full frontal, four quadrant-ed images circling the bottom 8').
It may well be that if it's a national champion, that the state coordinator has a photo.  That is the path that I frequently have had to take, in champion certification. Let us know of your progress!
-don
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View my Alaska Big Tree List Webpage at:
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