Will,
Good points. Actually, I often do as you do on really large trees, i.e. shoot to the side of the trunk to capture radius as part of the spoke. Bob ----- Original Message ----- From: "Will Blozan" <[email protected]> To: [email protected] Sent: Friday, January 8, 2010 12:40:53 PM GMT -05:00 US/Canada Eastern Subject: RE: [ENTS] Back to James on crown spread Bob, Great overview. I would add a few comments to clarify. 1) Shooting to the same height on the trunk is essential if the tree has significant lean. 2) I have found the laser WILL hit and return from the side of the trunk perpendicular to the point of observation. This would eliminate adding in the radius of the trunk. Incidentally I always use the side spot when possible for the base shots during height measurements to have a useful horizontal offset for future calculations, if needed. 3) Measuring the crown on branches over obstacles (like water in Congaree) is a technique all ENTS measurers should master and employ. It is very useful and provides at the worst a not-less-than data point for that portion of the crown. 4) I think the “ENTS spoke method” should be used by all tree lists and would best represent the crown dimensions. Max spread and longest limb system extension would be separate items to record. Will F. Blozan President, Eastern Native Tree Society President, Appalachian Arborists, Inc. "No sympathy for apathy" From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Friday, January 08, 2010 11:01 AM To: [email protected] Subject: [ENTS] Back to James on crown spread James, Crown spread measurements are a challenge, more so than simple explanations and measurement diagrams would lead the beginner to believe. Measuring the crown spread of an in-forest tree is an obvious headache to anyone who has tried it a few times. Open-grown trees in a field or park with full access is another matter. In ENTS we often find ourselves measuring forest-grown trees in difficult terrain. The traditional way is to measure the longest and shortest spreads and average then average them. Lots of luck. An alternative is to fin what you think is the longest spread, measure it and then rotate 90 degrees and take another spread measurement and average the two. These are the to methods of measuring crown spread that are commonly described. But without spending a lot of time, how do you know you've found the longest and shortest spreads? And even if you have, do they capture the average spread well enough? For trees that lend themselves to circling around, the best way to determine average crown spread is to circle the tree and shoot to the trunk from points along the drip line. If you're on sloping ground, shoot to the trunk with your laser and clinometer and compute horizontal distance to the center of the trunk by the calculation H = D x cos(A) + R, where D is the laser-measured slope distance to a point on the trunk, A is the angle, R is the trunk radius, and H is the computed level distance or spoke length. If C is average crown spread, then the final formula is: C = 2 x [SUM(H+R)]/N where N is the number of readings. C is obviously just double the average of all the H spoke lengths taken to the center of the tree. Of course, if you are measuring in yards, of course you have to multiply the final result by 3 to convert to feet. If you had your laser on meters, the factor is 3.28084. Alternatively you can compute C as: C = 2 x [SUM(H)/N + R] as an algebraic simplification of the first formula. Whether you add R to each spoke or to the ending average length of the spokes, don't for that step. Since radius varies with height, best to shoot to the trunk at a predetermined height or spot on the trunk where you've taken the girth and calculated the associated radius. R = C/(2 * Pi). This is usually at 4.5 feet, but doesn't have to be for the crown spread determination. Visibility and access always have to be taken into consideration. All of us who measure trees know this, but the simplified tree diagrams never discuss actual field conditions and how to deal with obstacle that obscure visibility. The more radial shots you, get the better. Just circle around the trunk following what you think is the drip line - if you can. Use the clinometer to position yourself at the extreme edge of the limb. You need to insure the angle is 90 degrees. Where a tree hangs over a roof, you have to get increasingly inventive. If you stand at the trunk and look out to what appears to be the greatest extension of the limbs over a roof, you can use H = D x cos(A) + R to calculate the horizontal distance away of what you can see as a tip. Of course, this may not be the fartherest extension, but you have to measure what you can see. One final point worth discussing, are we attempting to measure the spread of the crown as defined by branches and limbs, as opposed to the absence thereof? For example, suppose in circling the tree following the drip line, you reach a point where there are no branches of any consequence protruding out from the trunk, just small foliage near the top. You are really in a gap between outstretched limbs. Would you take spoke measurement here? Moving a few feet left or right wold put you back under overhanging foliage. Should that be your choice? It is for me. I don't typically include in my determination of crown spread places where limbs are missing, where you could follow a gap between foliage/limbs right up to the trunk or nearly so. We don't usually address this technicality in our discussions. Crown volume is an ENTS calculation that we have attempted to perfect to better capture those marvelous live oaks of Larry's. But despite playing with formulas a lot, I've never been satisfied with the results. Ed has had some good ideas. Basically, we are attempting to measure a highly irregular, partially filled space. Not an easy thing to do even for the most cooperative of trees. Hope this helps. Bob ----- Original Message ----- From: "James Parton" <[email protected]> To: "ENTSTrees" <[email protected]> Sent: Tuesday, January 5, 2010 11:38:12 AM GMT -05:00 US/Canada Eastern Subject: [ENTS] Re: Laser History and Measuring Tree Spread. Bob, Thanks for the explanation. One thing is for sure, I enjoy measuring trees by this method when I am out. I think I have it pretty much down but still I need more practice at being proficient at it. I was going over what I learned at Congaree last year, doing tree spread. They are a couple of ways. Take two measurements, four spokes and average them. Say 15y by 20y. You would add them together and divide them by two to get the average. right? And then take the answer and times that by three to get it in feet. 15+20=35 divided by 2=17.5 x3 = 52.5 That is 52.5 ft average spread. I also seen in Congaree where multiple measurements are made by circling the tree making multiple measurements for improved accuracy. I looked up and read on how to measure max and average spread on the website but wanted to know whether I had the averaging number formula right. I never was a math wiz. ~laughing~! I find it awesome that ENTS and a few independents have influenced tree measuring so much that Nikon and others now produce rangefinders to cater to that need. As you stated, before us rangefinders were made primarily for sporting activities. Hunters still use them a lot, for example. I have to thank all ENTS but especially You, Larry Tucei, Will Blozan and Ed Frank for helping me learn this amazing method. I would encourage all non measuring ents to learn it. It really is fun! James Parton On Jan 5, 9:39 am, [email protected] wrote: > James, > > BVP was independently using the sine top sine bottom method first. There may have been others as well, but I'm unaware of who they would have been. Will Blozan and I developed sine top and sine bottom for ENTS. We later discovered that BVP and been using it for a long time. Colby Rucker later joined Will and me and became known for his use of long poles to get a better fix on the lower measurement. Colby was just great. I miss him a lot. We all do. > > BVP was the one who introduced Will and me to the Litespeed 400, a Bushnell laser. I got one and so did Will. Everything was uphill thereafter. The rest is history. > > In terms of the tree math, my strong suit has always been mathematics. I developed mathematical models in my work while in the Pentagon and have taught math and statistics at the college level. So, tackling the problem in a mathematical way conforms to my nature. I say this because it has always come as a surprise to people outside the world of forestry that such basic calculations as we use haven't been in practice for decades. I always explain that those calculations were not possible prior to the introduction of the laser rangefinder. As to the expertise of mensurationists, they know the math. It's elementary, but they don't spend the time decoding hard to measure trees in forest situations. It's rather like knowing some principles of animal tracking versus being out there doing it. It took me three separate trips to tie down that tuliptree in Montpelier. I'm within +/- 0.5 feet of the twig I was measuring, but the effort required speaks to the difference of pointing, shooting, and writing down some numbers versus getting it right. ENTS knows better how to do that than any other group in the East. Of that, I have no doubt. > > The Forestry 550 does measure tree height by our sine top, sine bottom method. The TruPulse does it also, but not by the built in height routine. It requires mores steps. BVP's Impulse Laser also does it right, but not by the built in routine. He also must use more steps. The OPTILOGIC appears to do it by the old tangent method. Pity. > > Before ENTS people were using laser rangefinders in sports and other endeavors, but judging by the feedback we have gotten, ENTS has been really the only show in town in terms of employing laser rangefinders in tree height measuring. There's no way of knowing who might have been out there in tree-land doing it on their own. They didn't come forward. > > The tangent-clinometer method was used before ENTS. It has been in use for decades. I suspect that early measurements of standing trees employed this method with some instrument being used to measure the vertical angle. The method of similar triangles would also have been used. Descriptions of equipment used and measuring methodology have been lost, if they were ever known. Thus, we get reports of astounding tree heights, but no way of verifying them. We'll never know what grew in centuries past. > > A laser by its self can be used as you describe. However, looking upward and trying to shoot exactly straight up (90 degrees) is harder than one might imagine. When you think you are looking straight up, it is often at an angle of 70 to 75 degrees. A short make shift plumb bob can be used to create a true vertical line. > > I think this covers everything. > > Bob > > > > ----- Original Message ----- > From: "James Parton" > To: "ENTSTrees" > Sent: Monday, January 4, 2010 10:47:21 PM GMT -05:00 US/Canada Eastern > Subject: [ENTS] Re: Suunto vs. iPhone > > Bob, > > ENTS came up with the Sine-Top Sine-Bottom method of measuring, right? > I also know that some others have used lasers to measure trees more > recently? Has ENTS inspired the use of laser rangefinders as tree > measuring tools so much to grab Nikon's attention to build a laser > specifically for measuring trees? And then there is those Tru-Pulse > lasers and the one that BVP uses. Was lasers being used of any > frequency before ENTS? I have always thought the tangent clinometer- > only method was in use before You and Will developed our highly > accurate method. I also know that a laser can be used by itself from > under the tree if the top can be found as in a decideous tree in > winter without the need of the clinometer. > > Fill me in on laser usage history. > > James Parton > > On Jan 3, 3:19 pm, [email protected] wrote: > > Carolyn, > > > The Nikon Forestry 550 does it all. It is also fairly pricey. You select the height mode, shoot the crown, shoot the base, and read the calculated height from the LED. No math. No fuss. No bother. > > > Bob > > > ----- Original Message ----- > > From: "Carolyn Summers" > > To: [email protected] > > Sent: Sunday, January 3, 2010 2:35:23 PM GMT -05:00 US/Canada Eastern > > Subject: Re: [ENTS] Suunto vs. iPhone > > > Are there any tree-height measuring devices that do the math for you? I > > never took trig. > > -- > > Carolyn Summers > > 63 Ferndale Drive > > Hastings-on-Hudson, NY 10706 > > 914-478-5712 > > > > From: Beth > > > Reply-To: > > > Date: Tue, 22 Dec 2009 15:57:09 -0800 (PST) > > > To: ENTSTrees > > > Subject: [ENTS] Suunto vs. iPhone > > > > A Small Comparison between Suunto and iPhone Clinometers > > > > Since some of us now have iPhones and have downloaded the > > > Clinometer application I thought that someone needs to compare the > > > iPhone to the Suunto clinometer. Today I took 14 measurements each > > > while sitting on my couch to a ceiling heating/AC vent. I then > > > measured my eye height, the ceiling height, and the distance from my > > > eyes to the tape measure hanging from the vent as a plumb bob. These > > > measurements were: ceiling height = 96², height of the eyes = 38², and > > > distance to the vent plum bob = 219². I used the measurements to > > > calculate the angle I was trying to measure with the Suunto and > > > iPhone. Before taking my measurements I calibrated my iPhone > > > clinometer according to the instructions. I also had the following > > > settings: Fast approximation-on, Beep on lock-on, wait for lock > > > accuracy of + 0.1o- all the way to the left (+ 0.1o), disable auto- > > > lock-off, and 3D glass effect-on. > > > > The first thing that I do in order to calculate the angle A was to > > > calculate the distance from my eye to the ceiling; 96²-38²= 58². > > > > Since Tan A = a/b, we can rearrange the equation to find A by dividing > > > both sides by Tan. Since 1/Tan =Arc Tan the equation is A = (a/b) Arc > > > Tan. Filling in this equation with the data we get A = (58/219) Arc > > > Tan or A = 14.8336707057. Taking signifiginte numbers in mind I am > > > going to say the angle is 14.8o. (Note: I calculated this after > > > gathering the data as not to influence the clinometer data) > > > > Now for the clinometer data: > > > Suunto iPhone Suunto iPhone > > > 15.5 15.2 14.5 15.4 > > > 15.0 14.9 15.0 15.2 > > > 15.0 15.1 14.5 15.2 > > > 15.0 14.1 14.5 15.1 > > > 15.0 15.0 14.5 15.7 > > > 15.0 15.2 15.0 15.5 > > > 14.5 15.1 14.5 15.2 > > > The means were 14.8 and 15.1 for the Suunto and iPhone respectively > > > with standard deviation of 0.31 and 0.35. > > > > The one thing I noticed in my raw data is with the Suunto my highest > > > and lowest angles were 15.5 and 14.5 whereas with the iPhone they were > > > 15.7 and 14.1. I can think of at least two reasons why. 1) I have > > > more experience with the Suunto than I have with the iPhone and 2) the > > > Suunto has a line to help repeatly ³hit² the same spot whereas the > > > iPhone you are just looking down one side of the phone. > > > > I also noticed after calculating the angle (14.8) the Suunto average > > > was closer than the iPhone¹s (14.8 vs. 15.1). Now is 0.3o difference > > > significant? Bob has more experience with the Suunto than I do and he > > > has stated in the past that can read it to the nearest 1Ž4 o. I myself > > > can only read it to the nearest 1Ž2o. Given this I believe that a > > > difference of 0.3o is. > > > > How can the iPhone be improved? If one would add a sighting device on > > > to the iPhone this could help ³hit² the same spot repeatly. Obviously > > > this can not be same one that is used in the Suunto¹s, looking through > > > it with an optical illusion. Maybe a tiny gun sighting built into the > > > volume and/or ringer buttons on the left side. I think someone > > > thought of this earlier. With the sight and practice I believe one > > > could the angle down to the nearest tenth of a degree. With the > > > Suunto one can only really estimate anything less than 1 degree. > > > Beth > > > > -- > > > Eastern Native Tree Societyhttp://www.nativetreesociety.org > > > Send email to [email protected] > > > Visit this group athttp://groups.google.com/group/entstrees?hl=en > > > To unsubscribe send email to [email protected] > > > -- > > Eastern Native Tree Societyhttp://www.nativetreesociety.org > > Send email to [email protected] > > Visit this group athttp://groups.google.com/group/entstrees?hl=en > > To unsubscribe send email to [email protected] Hide quoted text - > > > - Show quoted text - > > -- > Eastern Native Tree Societyhttp://www.nativetreesociety.org > Send email to [email protected] > Visit this group athttp://groups.google.com/group/entstrees?hl=en > To unsubscribe send email to [email protected] Hide quoted text - > > - Show quoted text - -- 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]
