Bob- I'd be interested in participating...I'm advocating it enough, that I want to be able to put up (a defense) rather than shutup (when challenged). To be able to say, well here's a professional paper on it done in the ENTS Journal, read it and make your own judgments, would be great.
Come January, I'll be making a 6 month long push to get Alaska's Big Tree program up and running, and such a document would be handy down the line! -Don Date: Tue, 8 Dec 2009 22:40:01 +0000 From: [email protected] To: [email protected] Subject: Re: [ENTS] Finishing up in the Trees of Peace Don, Ed, As my field measuring season winds down, I plan to devote lots of time to the calibration issue, manufacture claims, field accuracy, etc. Of course, I'll be looking for input/advice from all of you as I go. The instrument accuracy and precision study could grow into a paper or at least an article in the ENTS Bulletin. Bob ----- Original Message ----- From: "Don Bertolette" <[email protected]> To: [email protected] Sent: Tuesday, December 8, 2009 5:09:40 PM GMT -05:00 US/Canada Eastern Subject: Re: [ENTS] Finishing up in the Trees of Peace Ed- On just the equipment accuracy alone, I don't entirely agree...I think it would be appropriate to remove 'speculative' claims and replace them with replicable engineering level spec testing...eg, comparing laser rangefinders height measurements:1)across expected array of heights (15' to say 200') and 2)across those heights with an array of reflectance surfaces that can be anticipated in the range of surfaces encountered in the woods, especially including reflectors. This should be a professional peer reviewed journal level research paper. Then we could discuss the living 'breathing' nature of trees, and 'significant' digits, without so many unknowns. I do know that Bob has done some fairly extensive field studies on this, but stops short of being easily replicable. As it is now, our assumptions are not beyond question, which I assume is the desirable ENTS objective? Don Sent from Don's iPhone 3GS... On Dec 8, 2009, at 11:45 AM, "Edward Frank" <[email protected]> wrote: Don, The question here is the precision of the laser measurements, accuracy is something different. The lasers are much more precise than the manufacturers accuracy statements. The readings are repeatable to much less than 1/2 yard or 1 yard. They are repeatable to at least a couple of tenths of a foot. The factory calibration and standard usage of the instruments results in the decrease in accuracy. If used properly - measuring at the so called click-over point the accuracy is the same as the precision. The reading are repeatable and accurate to a tenth of a foot or at worse a couple tenths of a foot. To get this degree of accuracy the instrument needs to be calibrated and measurements taken at a specific portion of the range - at the click-over point - otherwise the 1/2 yard is true. Also the error is not translatable directly into height errors. The amount of error in the length of a reading from laser errors is multiplied by the sin of the angle of measurement. Thus at 45 degrees the error in height from laser error is only 07x the laser error. So in usage the error in heights will range from around 1 foot with no corrections at all, at angles les than 60 degrees or so to less than a tenth of a foot if everything is done right. With multiple measurements the average, excluding outliers, represents the most probable height and is should most likely be expressed to the nearest 1/10 of a foot. I would agree that expressing the 100th of a foot represent non-significant digits. Expressing heights to a tenth of a foot can be supported. Ed -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] _________________________________________________________________ Get gifts for them and cashback for you. Try Bing now. http://www.bing.com/shopping/search?q=xbox+games&scope=cashback&form=MSHYCB&publ=WLHMTAG&crea=TEXT_MSHYCB_Shopping_Giftsforthem_cashback_1x1 -- Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected]
