Steve, No there isn't any difference in the accuracy of the clinometer at any angle. You just need to see the top of the tree. Generally being back enough so that the angle is close to 45 or so is generally better for seeing the true top. Steeper angles mean you are more likely to be at a point where the true top may be hidden by outward jutting branches. The farther you get away then the more the error in reading the clinometer accurately affects the accuracy of the measurement. The clinometer is mechanical, so if say it were off by 0.2 degrees high, it would read high 0.2 degrees at all angles. By shooting both the top and the bottom angle with the clinometer any intrinsic errors in the calibration of the clinometer will tend to offset between the top and bottom angles - not completely but close.
45 degrees is just a ball park suggestion. You need to find the top of the tree so you must shoot from wherever it gives you a good line of sight. Sometimes it will be steeper, sometimes a shallower angle. In general the key is to explore the top with the laser rangefinder scanning for the highest point. At the the same angle or within a couple of degrees, the greatest distance with the rangefinder - the higher the top. Typically what appears to be the top at first glance is not really the highest point. Scan around and find the highest combination of distance and angle. It may be a obscure branch back into the apparent top mass of canopy that is the actual highest point. Remember the branch at the greatest distance at or close to the steepest angle is the tallest top. Ed Join me in the Eastern Native Tree Society at http://www.nativetreesociety.org and in the Primal Forests - Ancient Trees Community at: http://primalforests.ning.com/ ----- Original Message ----- From: Steve Galehouse To: [email protected] Sent: Monday, October 06, 2008 10:54 PM Subject: [ENTS] Re: Measurement methodology question Bob, ENTS- Thanks, I borrowed one of my kids' calculators, and now know how to plug in the SINE function---SIN(degrees)value x laser distance--right? top and base. Is there any difference in accuracy regarding slope? Is taking a higher clinometer degree reading more accurate than a lower one? Steve On Sat, Oct 4, 2008 at 8:33 AM, <[EMAIL PROTECTED]> wrote: Steve, Unforntunately not. The slope scale IS the tangent value x 100 and its use assumes a level baseline. You have to use the laser distance to the actual target and the degrees to that target with the formula: distance x sine of angle. Bob -------------- Original message -------------- From: Steve G <[EMAIL PROTECTED]> > > ENTS > > I've just acquired a clinometer with both degree and percent scales. I > understand the sine method of measuring with clinometer and laser > rangefinder(at least I think I understand). Can I simplify an accurate > measurement by taking rangefinder distance times % slope of > clinometer, without translating a degree reading to a sine value? > Intuitively it seems it should get to get to the same figure from > different directions.--is this correct? > > Steve > --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org You are subscribed to the Google Groups "ENTSTrees" group. To post to this group, send email to [email protected] To unsubscribe send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/entstrees?hl=en -~----------~----~----~----~------~----~------~--~---
