Jeff, This is not a calculation for tree height but is a calculation for trunk length. It could be used to measure extents of branch lengths from tree trunk to branch tip.
It's application to tree height is in confirmation only. If one is measuring a nearly vertical tree where the top is not offset from the base, then this calculation is nearly equal to the height calculated by the sine method. If the tree height and trunk length differ significantly and the crown is expected to be over the base, then there is measurement error in the data set. It could be that another branch caused an unexpected short laser reading to the trunk or more likely to the crown. The law of cosines calculation will confirm this, but possibly not obvious enough for practical usage. Instead of confirming the validity of the data point measurements with the law of cosines, use the sum of cosines to get the actual horizontal offset to the points. Then, one can intuitively decide if the calculated horizontal offset is comparable to what appears to be seen on site and then decide if the measurements need to be thrown out and remeasured. Paul J. ----- Original Message ----- From: "Jeffs Email" <[email protected]> To: <[email protected]> Sent: Sunday, February 08, 2009 8:00 PM Subject: [ENTS] Re: Bank of solved problems > > Bob, > > Learned something new there. I can see how Paul Jost applies this to > determining tree height with this. I carried the decimal answer I had > out to the third digit and ended up with 40.87 which matches up with > the supplied answer. Assuming you stayed 'within the plane' of a limb, > this could also be applied to limb length as well could it not? It > would rely on your rangefinder being able to resolve only the target > you want, but could be done, correct? > > This was my solution: > For lack of characters on my phone, well substitute ^ for square and > sqrt for square root. > > 65^ + 70^ - 2(65 x 70)cos35 > 4225 + 4900 - 7454.283 = 1670.717 > sqrt1670.717 = 40.87 > > Jeff > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
