Dr. Dean Coble, professor of forest biometrics, and Jason Grogan, research associate, illustrate how to measure the height of a tree using a yardstick.
When the yardstick comes out, the hard hats go on. Thanks for keeping it safe, gentlemen.
killedbycoconuts
A perfect YouTube video! Useful and informative. No 3 minute introductory scene with spinning logos. No going off on tangents about the history of the yardstick. No electric guitar soundtrack that drowns everything out. No begging for the users to "click the subscribe button and the 'like' button as well".
TheDunestrider
If anyone is wondering what the geometry behind this is, you're basically making an isosceles (two sides the same length) triangle out of the 30" stick, the 30" line from your eye to the bottom of the stick, and the line from your eye to the top of the stick.
Lining the stick up with the tree creates a much larger but geometrically similar (same shape) triangle consisting of the tree, the line from your eye to the bottom of the tree, and the line from your eye to the top of the tree.
Since the two triangles are similar (same shape), the fact the length of the line from your eye to the bottom of your stick (30") is the same as the length of your stick (30") means the length of the line from your eye to the bottom of the tree (60') must be the same as the height of the tree (60').
As a side note, we can see that when he measures the length of the line from his eye to where he will be holding the bottom of his stick, he holds his arm slightly higher than when he is actually lining up the stick with the tree. The true length of the line from his eyes to the bottom of the stick is therefore likely slightly over 30", since holding it lower will make it farther from his eye. Consequently in the larger similar triangle we would expect the length of line from his eye to the bottom of the tree (60') to be slightly longer than the true height of the tree (56'), which turns out to be the case.
danmcgoogleaccount
Every day is a day for learning. Thank you very much!
CustomJ
Pretty nifty. I always just cut em down to see how tall they were
The_Cat_Authority
Super helpful and interesting geometric exercise. Also fun to tease you about wearing a helmet for this dangerous task!
frankposterello
Military method: take any straight object (pen, stick, tent stake, etc.) and hold it vertically at full arm extension as you did in the video. Position the top of your stick level with the top of the tree, and position your thumb level with the bottom. Then rotate your measuring object 90 degrees while still at full arm extension. Position your thumb against the tree and have a buddy pace out to the end of your measuring object. Your hight estimation will be as accurate as the pacer's pace count. If you use the measuring tape, it will be accurate within a couple of percent.
This is how pathfinders determine the correct amount of standoff from obstacles for the approach and departure ends of a helicopter landing zone or parachute drop zone.
Night_Monkey
This is why I love YouTube. very informative video, I will archive this in my brain until the day, who knows when, I can use it. Thank you.
tyarthas
This is EXACTLY the type and quality of video I was hoping to find!!! THANK YOU. My 10 yr old daughter and I had the discussion of how to determine tree(or other object) height from any given distance while while walking to school yesterday... and now we know the distance is key and more importantly... we don't need special tools. This is perfect. Well done...
matycee
You can do something similar with a speed square by placing the square on a level surface aligned to the base of the tree and then sighting down the 45° angle of the square aligning it to the tree top measure the distance from the tree to the square. This works because a 45° inclines run and rise match.
ReEvoluion
If one tilts their head back when siting the top of the tree, that introduces that 6 foot error. Site the top of the tree past the yardstick only moving your eyes and the estimate will be even closer. Great video, I needed this information!!
SMart
Excellent presentation and beautifully simple principle. Thanks for taking the time 👍
matter
We used this method as arborists to determine where a tree will land once felled, although we used pace counts, not the measuring tape. Does a very good job at preventing property damage/personal injury, so long as your notch cutting skills are on point!
mouthwash
Your explanation is the methodology of the billmore stick. I worked in coastal BC Canada where ground conditions are highly variable and trees up to 90 meters tall have been measured. 60 meter trees were not uncommon. Basic method we use to use was a simple sunto clinometer to measure the angle difference top to bottom in % instead of degrees x horizontal distance in meters. Worked well for variable distances necessary. Lasers were a real innovation for timber cruising in big timber.
xrayeyes
When we were kids we measured the shadow cast by the yard stick and the shadow cast by the tree and simply plugged it into a fractional equation, e.g. 36"/60" x/120' Other than the fuzzy tip of the shadow, it was pretty accurate. It was also a great way to motivate kids to learn math.
shnarklevonbarkle
Great video! You don’t need a yardstick, you can use any stick. You don’t need a tape either, just heel/toe steps and a knowledge of how big your shoes are. Try it!
DireWolfForge
For city trees, keep in mind that a standard telephone pole is 35 feet tall. Sometimes you can measure a tree against one.
bsqkkub
Excellent demonstration, super easy to follow and very neat method to complement the "rule of thumb" method for distances. Similar right isosceles triangles for the win!
AD-bxfm
Stand your yardstick or ruler on the ground pointing straight up. Measure the shadow of the stick. If the shadow is half the height of your stick - the shadow of the tree will be half the height of the tree. You just need to figure the ratio of a known object to the unknown object's height. The ratio will be the same.
OregonDARRYL
Man that is very informative..Its always good to learn things...I generally just go down to the local bar and complain about a tree I have to deal with...and after a while some retired ( loggers never retire) cutter will say let me come over and look at it... never costs more than a bottle of whiskey and drinks around the campfire.... cheap at twice the price..everybody is happy...I share the firewood with them and have all I need...
