External Baseline Method

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

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#1)  External Baseline Method

Postby dbhguru » Sat Sep 17, 2011 11:48 am

NTS,

   The attached Excel spreadsheet may soon make the rounds within DCR's Bureau of Forestry now that I've connected with the Chief Management Forester for the State. He and I hit it off well on a walk in MTSF on Sept 9th, and like our buddy WNTS president Don Bertolette, Bill Hill has a surveying background. So, he isn't intimidated by the trigonometry. Things are definitely looking up for the acceptance of NTS and its tree measurements within the departments of DCR. We've always had supporters in DCR like Northern Berkshire District Manager Tim Zelazo, but I think our reach will be extended considerably among the rank and file. I've promised Bill to work up data on rates of carbon sequestration in the Mohawk pine stands. Lots of work and careful measuring, but that's what I'd be doing anyway.

   Please note that in the spreadsheet, I made a comparison between heights obtained from straight shots with the TruPulse 360 versus the Extended Baseline Method (EBM). Difference average only 0.5 feet. EBM is here to stay. It works where direct access to the trunk is a problem and/or hitting the target with the laser is a problem because of intervening clutter.

   When the weather turns cold and snowy, I'll return to the Triangle Method and other esoteric measuring challenges, conferring with WNTS Vice President Michael Taylor.

Bob
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: External Baseline Method

Postby edfrank » Mon Sep 26, 2011 10:53 pm

Neat stuff Bob.  Keep up the research and post even if you get few replies.
"I love science and it pains me to think that so many are terrified of the subject or feel that choosing science means you cannot also choose compassion, or the arts, or be awe by nature. Science is not meant to cure us of mystery, but to reinvent and revigorate it." by Robert M. Sapolsky
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#3)  Re: External Baseline Method

Postby dbhguru » Mon Oct 10, 2011 3:57 pm

NTS,

   Several days ago, I performed another test of EBM. The first baseline was 31.9 feet in length and the target was 73 feet above eye level from the closer end of the baseline. The TP360 gave a height of 73.0 feet. The EBM yielded 72.8. A second test used a baseline 37.9 feet in length for a target of 70.5 feet above eye level at the nearer end of the baseline. EBM yielded 71.5 feet for a 1.0 foot difference. The average of the two is a 0.5-foot difference, which is exactly what my long term average is. EBM works! That said, it is not exactly a breeze to employ. Its value is limited to certain situations, but it is a stand-in for the laser-based sine-sine method when the measurer can't get reliable laser returns.

  After the conference and rendezvous, I'll complete a spreadsheet which will allow one to investigate height errors from any combination of angle and baseline distance errors. It has to be done via a program or spreadsheet. The formulas involved are far too cumbersome to be applied with a simple calculator.

  EBM is not for a measurer who just wants to get into the ball park. EBM is for folks who need to breathe the rarified air accompanying the achievement of higher levels of accuracy, but who don't possess a laser rangefinder. A clinometer, tape measure, and two tripods or equivalents are needed. A plumb bob is useful to align the baseline and the target. The following diagram shows the method with formula. I have the formula programmed into my iPhone 4. Piece of cake - well, a heck of a big piece.

               
                       
Picture 2.jpg
                                       
               


Bob
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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#4)  Re: External Baseline Method

Postby Larry Tucei » Wed Oct 12, 2011 8:47 am

Bob,  Really cool formulas. I can see where they would really help the measurer when you can't see the top of the tree or on a slope etc. I remember BVT measuring with a Tru-Pluse at Congaree and Biltmore. I wish I could afford one- maybe someday they will be less expensive. I never tire of all your fabulous formulas.   Bob the Formula/White Pine/Writer/ Guru!    You da man!  Larry
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#5)  Re: External Baseline Method

Postby dbhguru » Wed Oct 26, 2011 9:49 pm

NTS,

   Attached is the latest and greatest tangent-based method workbook. If anyone wants to discuss the method and the error analysis, please let me know.

Bob
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#6)  Re: External Baseline Method

Postby Larry Tucei » Wed Oct 26, 2011 9:58 pm

Bob,  Impressive Formulas.  I wish I could use excel 1/4 as well as you do. Most of the forumlas you come up with are amazing and I bet time consuming. I understand them but have no Idea how to do the math with them. Good thing you plug it all in.  Larry
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#7)  Re: External Baseline Method

Postby dbhguru » Thu Oct 27, 2011 9:37 am

Larry,

    Unfortunately, I'm not good at catching my own errors. Fortunately, Michael Taylor is, and going through the process now, proofing. I'll no doubt have another version of the workbook in a few days. Soon we'll be able to reduce the EBM process to a few easy to follow rules and the spreadsheet to do all the calculations.

    Michael believes that if we have the right equipment, EBM can out perform the Impulse Laser 200LR. That's saying a lot. However, Michael excels at designing inexpensive equipment that out performs the big stuff. So far he has a pretty good track record, and that offers hope. There's not much chance that many people will be able to afford a TruPulse 360. Using that instrument on a tripod, I can get accuracy to 0.1 degrees for angle measure. However, using an instrument Michael sent me, I can get accuracy to at least 1/60th of a degree, and with some statistics, close to 1/100th of a degree. Now, that is accuracy.

Bob
Robert T. Leverett
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Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
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#8)  Re: External Baseline Method

Postby dbhguru » Tue Nov 01, 2011 8:57 pm

NTS,

  The latest version of EBM is attached. Don, Michael, and I would appreciate any feedback any of you would be willing to give. At this point, I'm solely responsible for the mess. Please don't blame them. My objective is to take tangent based techniques to the limits. I start with the basic method and move on from there. I'm sure the graphics could be better. Don't worry about the math unless you want to wade through it. Otherwise, Michael will do the proofing of the equations.

  Assuming you see merit in this project, where should we take it? Thanks in advance for any feedback.

Bob
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#9)  Re: External Baseline Method

Postby Joe » Wed Nov 02, 2011 7:23 am

I'd be shocked if any DCR person EVER meaures any tree with your advanced methods, Bob. Though, it's probably not important that they do- only that they know such methods exist and then they'll be careful publishing the usual poor numbers.
Joe
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#10)  Re: External Baseline Method

Postby dbhguru » Wed Nov 02, 2011 1:29 pm

Joe,

    Inroads are there to be made, partly through the efforts of research foresters like Dr. Don Bragg who commands respect. However, other avenues are opening up to education. Tomorrow, Michael Taylor and I will consult with Laser Technologies Inc. on uses of and potential improvements to the TruPulse 360 (and probably the TruPulse 200 as well). I've done a lot of practical field testing of both instruments and can speak to what they do well and not so well. Michael is full of ideas on how to improve the TP 360. It will be an interesting first meeting. Hopefully, other meetings will follow.

    The TruPulse 360 was designed mainly for the forestry community. I don't feel qualified to speak to purely forestry uses, however, I can think of improvements that would benefit other fields such as ecology and maybe geology. I'd have to be careful on the latter, though. I'd want to first consult with big Ed. One improvement I plan to discuss tomorrow is a routine to compute the area of a polygon. The internal missing line routine of the TP 360 would provide the basis for area computations projected onto either horizontal or vertical plane.

    Lots to think about.

Bob
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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