JUDGING TREE HEIGHT WITH GEOMETRY

[HART]

YEARS AGO I READ METHOD OF DETERMINING HEIGHT OF TREE. SEEMS LIKE YOU STOOD AT BASE OF TRUNK, MEASURED UP , LIKE SIX FT. MAYBE THEN BACKED OFF WITH MEASURING STICK UNTIL LENGTH OF STICK EQUALED .... SOMETHING... BUT THERE MY MEMORY FAILS.. HEY, IT WAS 65 YRS. AGO SO DON'T LAUGH! I KNOW BIG DOG, GEO. WILLER, RUDY, AND COUPLE OTHERS CAN DESCRIBE IT SO EVEN I CAN UNDERSTAND. THANKS,

[George Willer]

Hart,

Come on over and we'll practice on some of my trees.

Basically you have to know the distance of a reference point and the angle at that point between the line of sight to the base of the tree and the line of sight to the top of the tree. From that information many of us can calculate the height. There are several methods. Most of them assume fairly level terrain.

A stick could be set up at an intermediate point at a known distance to set up a proportionate triangle.

My memory is fresh... it's only been maybe 60 years since whenever we did that in math class.

I no longer have a transit to make it easy.

[Rudi]

Hart:

I am not great on theorems.. but.. my favourite one is Pythagorean Theory. This is one I have always used in laying out squares.. and a 25 pack of Cdn smokes was perfect to remind me of the theory.

A squared plus B squared = C squared or in the case of smokes 3x3 plus 4x4 = 5x5 or 25

You can measure the height of a tree the same way. I Googled - "Triangulation to determine tree height" . and found this Measuring Tree Heights

Hope this helps.

[Bigdog]

Take a stick, make a mark on the trunk of the tree at the end of the stick. Cut the tree off with a chainsaw and it will be exactly the same height as the stick................

[Don McCombs]

Hart,

I think what you are describing is the Biltmore Stick. Check this link.
http://www.tree-tech.com/reports/biltmore_stick.xhtml

[Bob McCarty]

Rudi, Can I borrow your clinometer for the weekend? In Boy Scouts, we would have a Scout of known height (5" was pretty common back then)stand in front of the tree. You'd then hold a stick at arms length vertically with the top end even with the top of the tree and slide your finger until it was even with the base. You'd then take a finger from the other hand, mark the top of the scout, slide the stick down, mark the top of the head again and again until you ran out of stick. Then multiply 5' by the number of slides you did. Not as accurate as these other methods, but no calculator needed.

Bob

[spiveyman]

If you want to kick it up a notch, you could try making a proportion. you guys correct me if i'm wrong, but theoretically you could drive a stake in the ground, measure it, its shadow and the trees shadow, then figure out the height of the tree, represented below as "x" . set it up just like below, then 'cross multiply' the top left number with the bottom right, then the top right number with the bottom left. you set them equal to each other and then you have a basic algebra problem. i used a few common whole numbers for simplicity's sake. Give it a try if you have nothing better to do!

[grumpy]

The math is killing my small brain. You would need 2 measurements to do the math and if ya had that you would already know the heigth.We took a stick and eyeballed the tree from far enough away that you could get the whole tree length on the stick then flipped it 90 degrees from the base of the tree and found the end of the mark and measured the length on the ground. Know what I mean?? Hope so. It's fairly accurate too. Grump

[spiveyman]

o but grumpy, that'd be too simple!! why not have some fun with it? lol

[cowboy]

Or you can use my polish method. Usually I imagine a 45% angle to the top of th etree and thats usually where it lands. Or if the space is tight. Asuming the ground is flat. Put a speed square on a level get it level and to looking up the 45% side line it up to the top of the tree. Look down it from it to the ground and thats where it will hit. If you mesure from there back to the tree thats how tall it is.

Billy

[Bigschuss]

What doesn't kill you makes you stronger.

When I stopped lifting weights...that didn't kill me. So, does that mean that not lifting weights only makes me stronger?

In my Biology class I teach my students how to do this. We make home made clinometers using a small plastic protractor. If you measure the distance from the tree you are trying to estimate, and then record the angle between the viewer and the top of the tree with the clinometer, you will have all you need to estimate the tree's height.

The formula is:
[distance from tree] [tangent of the angle] + [height of the person recording the angle] = tree height

[spiveyman]

When I stopped lifting weights...that didn't kill me. So, does that mean that not lifting weights only makes me stronger?

hmm....looks to me to from your math that maybe you had free time to work on mathematics and become mentally stronger?? u got me cornered there ....

[John *.?-!.* cub owner]

You guys make things way to complicated. Have someone of known height stand at the base of the tree ( a 6 footer works great). Stand back a few yards and say, yup , it is about 5 times as high.

[Jim Becker]

In my Biology class I teach my students how to do this. We make home made clinometers using a small plastic protractor. If you measure the distance from the tree you are trying to estimate, and then record the angle between the viewer and the top of the tree with the clinometer, you will have all you need to estimate the tree's height.

The formula is:
[distance from tree] [tangent of the angle] + [height of the person recording the angle] = tree height

OK, next question, how to do it without the clinometer/protractor? Here is a hint, it will be easier next week.

[John *.?-!.* cub owner]

OK, next question, how to do it without the clinometer/protractor? Here is a hint, it will be easier next week.

cut it down, but then you will be measuring ho long it is, not how tall.