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measuring tree height

Posted by tenacre Z5 SW MI (My Page) on
Tue, Jul 22, 14 at 21:45

Other than measuring shadow, are there other ways that don't require expensive equipment?

I'm talking about trees 30 to 50 feet tall.


Follow-Up Postings:

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RE: measuring tree height

  • Posted by whaas 5a SE WI (My Page) on
    Tue, Jul 22, 14 at 22:04

Take a picture of the tree with an object/person of a known height (a round number) and you can estimate the height. Similar concept with that pre-measured hash in the bottom right hand corner of a map.


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RE: measuring tree height

> Posted by whaas 5a SE WI (My Page) on
> Tue, Jul 22, 14 at 22:04

> Take a picture of the tree with an object/person of a known height (a round number)
> and you can estimate the height. Similar concept with that pre-measured hash
> in the bottom right hand corner of a map.

That's the way I had been doing it, then realized there's a substantial error due to the angle from the top of the tree to the camera.

Anyone know how to correct for that? I'd like to get an accuracy within 1 foot for the height.


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RE: measuring tree height

Here is something you can try.... see link for instructions.

Here is a link that might be useful: Measuring Tree Height Video


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RE: measuring tree height

There are folks on here who can give you the best methods, but I have never been able to use there methods. Good luck to you, it is likely that someone will easily be able to use the methods others have for many years. There is a tool used by some a "Clinometer" if I spelled it right. But I haven't been able to use that myself. I have never been good at Math. Science was something I did a bit better at, though. I hope someone can say "ok" "you step back x amount of ft from the trunk" and then' it is so many ft up the trunk equals a height of "?" But really any help on determinating tree height is welcome. There is a method using a 12" ruler, but I would hope somebody has come up with something better. The best method is someone going to the top and dropping a rope. I hope you find someone that is willing to do the measuring job right.


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RE: measuring tree height

I have quite a few trees around the 25 to 30 metres height (up to 100 feet). One came down in a cyclone and I measured it on the ground at just over 26 metres. Made me curious about exactly how high the other were. So I checked around for cheap clinometers but it appears the words "cheap" and "clinometer" don't go together. So I made my own.

Used a camera tripod as the base and a long thin cardboard tube. From my schoolboy knowledge of algebra I knew that the only technical bit that was needed was a 45 degree angle. You fix the tube to the tripod at 45 degrees and move the whole lot to the point where the top of the tree appears in the tube. A piece of string is run out from the tube to the ground (at the same angle as the tube - 45 degrees). Then, the distance from where the string touches the ground to the tree is the distance to the top of the tree.

No need for advanced algebra.


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RE: measuring tree height

> Posted by tropicbreezent
> Wed, Jul 23, 14 at 0:56
> Used a camera tripod as the base...
> You fix the tube to the tripod at 45 degrees...

The largest source of error for this technique is making sure the tube is precisely at 45 degrees from horizontal.

One degree of error puts you off by a yard for a 100 foot tree.

This post was edited by tenacre on Wed, Jul 23, 14 at 7:47


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RE: measuring tree height

and the ground has to be level;

I use the triangle thing to approximate. I wouldn't trust to 1', but for rough height estimates it works great.


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RE: measuring tree height

why is precision of such importance???

a common garden spade is 6 foot.. measure yours ... place it against trunk ... keeping backing up until the whole tree fits in the view finder .. snap pic.. use shovel as 'known' scale when comparing on computer screen ..

close enough in my world ...

beyond that version of winging it ...

if you insist on more precision .. see link ... you will need a measuring tape.. and a protractor .. if you know two angles.. 90 degrees and 45... and the distance from the trunk ... you should be able to figure out the other two sides ... i think its a function of a multiple of one.. based on the second drawing .. 1 - 1 - square root of two ... if you dont have that space... then use a 60 degree angle.. etc... are you starting to see why the shovel is looking easier.. and easier... lol

or.. the final option ... wet thumb ... look at tree.. raise thumb to eye level ... and simply declare the tree 45 feet.. and be done with it... state it affirmatively.. aloud.. if anyone is watching ... and if they question your wisdom.. begin to bore them to death with geometry ... until they change the subject ... lol ....

ken

Here is a link that might be useful: link


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RE: measuring tree height

I lay on the ground at the base of the tree and with a broom (weight on bottom of broom will help you later) I get the top of the tree level to the top of the broom stick and then the base of the tree I hold my thumb on the broom handle where that is.

Then I walk away in a straight line, always holding my thumb on the broom handle and when I reach a distance where when the broom handle is "plumb/perpendicular" to the ground and the tree is exactly between my my thumb and the top of the handle I put a temp stake in the ground and using a tape measure I record the distance back to the trunk of the tree.

That's the height.

Dax


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RE: measuring tree height

> Posted by ken_adrian MI z5
> Wed, Jul 23, 14 at 9:07
> why is precision of such importance???

Some people prefer white flowers, other people prefer red.

Some people are interested in tree height, other people don't care.

Vive la difference


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RE: measuring tree height

> Posted by gardener365 IL 5b
> Wed, Jul 23, 14 at 9:47

> I lay on the ground at the base of the tree and with a broom
> (weight on bottom of broom will help you later) I get the top of
> the tree level to the top of the broom stick and then the base
> of the tree I hold my thumb on the broom handle where that is....

I'm having trouble picturing the procedure you described. For example, what do you mean by "I get the top of the tree level to the top of the broom stick" ?


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RE: measuring tree height

> Posted by ken_adrian MI z5
> Wed, Jul 23, 14 at 9:07

> if you insist on more precision .. see link ... you will need a
> measuring tape.. and a protractor .. if you know two angles.. 90
> degrees and 45... and the distance from the trunk ... you should
> be able to figure out the other two sides ...

Thanks Ken.

Trying to measure angles with a protractor won't give the accuracy I'm looking for.

I know how to use a transit, but I don't have one. I'm going to keep an eye on Craigslist and see if I can pick one up.

In the meanwhile, here's how I've been doing the measurements:

Step1

Pick a spot at least 3 times the estimated height away from the tree where I have a clear view of the top of the tree and a clear view of at least 3 feet at the trunk of the tree.

Step2

Put two horizontal strips of white tape at least 3 ft apart on the trunk.

Step3

Measure X = distance from top edge of top tape to bottom edge of bottom tape

Measure Y = distance from bottom edge of bottom tape to the ground

Step4

Go back to the spot selected in Step1 and take a picture of the tree (top to bottom)

Step5

Download the pic to a computer and open it with Gimp (http://www.gimp.org).

Step6

Using Gimp's "measure" tool,

Measure Xp = number of pixels of distance X

Measure Zp = number of pixels from bottom edge of bottom tape to top of tree

Step7

Compute tree height H = (Zp/Xp)*X + Y


Problem with this method: The elevation angle from the camera to the top of the tree distorts the measurement. This can be significant.

This can be mitigated by standing as far away from the tree as possible, and using a camera with a high optical zoom.

It may also be possible to correct for the angle distortion by measuring the distance from the camera to the tree and using a little trig.


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RE: measuring tree height

Hey 10: it's exactly what I said. When you lay near the trunk you eyeball from any spot (move around until you are able to get the broom stick in a position where you can see the top of the tree is level with the top of the broom handle and where you are able to see the base of the tree (ground level) all within one "look."

You're going to see the angle is 45-degrees. It's natural. I was taught this method from the author of 'Native Trees for North American Landscapes'. It does not matter if you're two feet from the trunk or three or four or one, etc-. As soon as the tree is between "a certain distance on the broom handle" you start walking in a straight line, away.

Dax


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RE: measuring tree height

Hey Dax,

I'm sure that your description is perfectly clear to someone who is already familiar with the method.

Would you be so kind as to post a sketch, or a link to a site with an illustration?

Thank you.


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RE: measuring tree height

  • Posted by whaas 5a SE WI (My Page) on
    Wed, Jul 23, 14 at 11:41

Nothing here will work to your precise requirements. You will need to literally measure it or used advanced equipment.

I'm just assuming this based on your comment that if you have a 100' tree and you estimate 97' that that isn't good enough.

You want within 12". How do you select perfectly the peak shoot and account for wind??


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RE: measuring tree height

My friend always said: "you will be within (feet) of preciseness"

I've remeasured the same tree starting over again and was always within a few feet of my original measurement. Two times, three times, four times... within feet.

Dax

 photo MeasuringTreeHeight001.jpg


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RE: measuring tree height

> Posted by whaas 5a SE WI
> Wed, Jul 23, 14 at 11:41
> Nothing here will work to your precise requirements.

Possibly, but I'm not yet convinced that's true. I think the camera method may be quite accurate if done with great care, and the results adjusted appropriately for focal length, vertical centering of the picture, and distance of the camera from the tree.

I'm researching the proper way to make the adjustments. I'll post some pix and calculations if I ever get it figured out.

Wind is not a problem; just pick a day when there's no wind. Identifying the top shoot is surprisingly easy with a good lens and the right lighting conditions.


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RE: measuring tree height

Where anyone lays on the ground and "sights" their tree on the broomstick is where the distance should be measured to (not all the way to the trunk.) I hadn't done it for a while and realized I wrote a tiny error there.

You see in my picture the person head is a few feet away from the tree, draw a vertical line there right at the intersection of the dottled line "V" and put a stake in the ground and then walk away as far as necessary, put another stake in the ground, measure between the two stakes, and, that's your height.

This whaas is what a person does if a tree in question may be a state champion and if it appears it could/is, then someone with more professional equipment is brought in. I don't doubt a tree author, a close friend, and a man who has studied trees all his lifetime and is in his 60's. Yo! lol, and you know him to boot, lol...

Take care,

Dax


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RE: measuring tree height

OK, here's a report on what I've found.

I have a maple in an area with fairly horizontal ground and lots of clearance all around. I selected that for my test tree.

Method1: camera

I used the camera method as I described in detail in an earlier post in this thread.

Here's the raw data:

X = 68.5 cm
Y = 23 cm

Xp = 97 pixels
Zp = 1482 pixels

Here's the calculation:

H = (Zp/Xp)*X + Y = (1482/97)*68.5 + 23 = 1069.6 cm = 35.1 feet


Method2: shadow

St = length of tree shadow = 73.2 feet

Ss = length of stick shadow = 11.67 feet

S = stick length = 5.97 feet

T = height of tree = (St/Ss)*S = (73.2/11.67)*5.97 = 37.4 feet


Method3: 45 degree sight & level (see picture below)

37.8 feet

You can see how different the camera method measurement is.

This post was edited by tenacre on Wed, Jul 30, 14 at 11:33


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RE: measuring tree height

  • Posted by whaas 5a SE WI (My Page) on
    Wed, Jul 23, 14 at 20:07

Now get that tape measure and climb the tree and see what you get, lol


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RE: measuring tree height

I'm way past my tree-climbing years. Can't risk breaking bones any more. It took me two years to recover from my broken ankle in 1990.

Besides, among the hundreds of trees that I tend, this is one of my top three favorites. I wouldn't want to damage it in any way by climbing.

When/if I find a reasonably-priced transit I will re-measure the tree by measuring the elevation angle (alpha) to the top of the tree, the declination angle (beta) to the base of the tree, and the distance (d) from the tree.


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RE: measuring tree height

  • Posted by whaas 5a SE WI (My Page) on
    Wed, Jul 23, 14 at 21:33

None the less good post for others to reference in the future.

I'm one to admire a tree for its habit and texture and don't think too much of the height.

Now only if we can get some traffic on that pruning post.


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RE: measuring tree height

There is an old Shingle oak which I have wanted to enter in the Champion tree program, but I cannot measure it in "tallness" it may not be wide enough. Here is a pic of my dad near the trunk:  photo DSC00029.jpg It is pretty big as far as the trunk, but the height is hard to determine.


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RE: measuring tree height

poaky.. you are older than i thought .. lol ..

you said ... Champion tree program

i would be surprised.. that they could not give you guidance.. or send over some highly interested peep who can do it ...

have you ever contacted them???

ken


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RE: measuring tree height

> but the height is hard to determine.

Why? It looks to be in a fairly level area with lots of clearance.

.


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RE: measuring tree height

  • Posted by beng z6 western MD (My Page) on
    Sun, Jul 27, 14 at 9:27

Tie a highly-visible tape around a trunk a measured distance from the ground. The higher the better. Take a pic of the whole tree and view the pic in a scaled image viewer (even primitive Microsoft Paint has that). Use proportion against the known tape-height to figure the height. Not perfect because of a small perspective error, but quick & easy.


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RE: measuring tree height

Beng's method will work.

If you back off quite a ways, and if possible shoot from a ladder, the error will be less.

If you REALLY need accuracy within the range you stated, hire a surveyor.


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RE: measuring tree height

The camera perspective error can be significant; 10% or even more if you're too close to the tree.

Moving further away reduces the error significantly.

Raising the camera as high as possible (but not more than half the height of the tree) will reduce the error as well.

This post was edited by tenacre on Wed, Jul 30, 14 at 11:22


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RE: measuring tree height

I'd like to hear what you come up with using a broomstick for my own curiosity.

Regards,

Dax


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RE: measuring tree height

> I'd like to hear what you come up with using a broomstick
> for my own curiosity.

I would be happy to oblige, but I'm sorry to admit that I still do not understand the procedure, despite your graciousness in drawing that sketch for me.

The part I don't understand is the laying on the ground part. When the person is on the ground, what is the orientation of the broomstick with respect to the tree, and with respect to the person?

.


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RE: measuring tree height

Moving further away from the tree and raising the height of the camera reduces the error significantly.

This post was edited by tenacre on Wed, Jul 30, 14 at 11:28


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RE: measuring tree height

Here's a way with only a tape measure and a known-height object.

Take a stick. Use a ten foot piece of pvc pipe for example. This is an arbitrary height.

Lay down on the ground a hundred feet away. This is an arbitrary distance.

Have Uncle Harry walk between the tree and your head, holding that stick straight up and down, until the top of the stick, the tree top, and your poor eyeball all line up.

Have Uncle Harry stop. Measure from your eyeball to the stick base. Measure from your eyeball to the tree base.

The rest is basic proportional math. A mirror on the ground can substitute for sticking your eyeball on the ground.


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RE: measuring tree height

You have to lay anywhere so you are able to view the tree from the base to the top on the broomstick (top of broomstick = top of tree). You eyeball the top of the tree and the base on the broomstick. It's simply eyeballing... then where you were laying and where the broomstick was, right there place a stake in the ground. If you don't want to hold your thumb/finger-thumb on the broomstick for the base measurement, draw a line there instead with a marker. Walk away in a straight line from where you were laying and continue to look between the marks until the tree is visable between the top of the broomstick and the mark you made with a marker. Holding the broomstick with your arm completely extended and so it balances itself plumb and at eye level (your eye is basically in the "middle range" between your marks) ......when your arm is extended as to put the tree in view between your 'marks' at that distance away.....directly beneath the plumb broom - that's where you stick another stake in the ground and begin measuring between those stakes: Distance = Height.

Dax


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RE: measuring tree height

What's 'proportional' mean Grubby? You had me just fine until you said proportional. Add a mirror to substitute for an eyeball and you blew me away into Einstein zone!

Dax


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RE: measuring tree height

Moving further away from the tree and raising the height of the camera helps to reduce the error.

This post was edited by tenacre on Wed, Jul 30, 14 at 11:25


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RE: measuring tree height

Most builders and tradesmen have laser measurers, if you borrowed one and measured the distance from the ground to the top, (at night where you can see the red spot), you would have an instant hypotenuse - basic trigonometry will then give you the height of the tree.

A Leica Disto D2 retails around £120, they are really useful if you do a lot of measuring.


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RE: measuring tree height

When the person is on the ground, what is the orientation of the broomstick? Is it vertical or horizontal?

And how far is it supposed to be from the person's eye?

.


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RE: measuring tree height

It's at an angle about 45, but don't concentrate on a perfect 45 etc. Hold the broom with your arm extended and tilt the broom and your head back until the top becomes in view while you may still see the base of the tree.

Dax


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RE: measuring tree height

My apologies; I just can't conjure a mental image of how this broomstick method is supposed to be performed.

It's probably just me; but I need either a video (not gonna happen) or a description using the language of mathematics.

Could someone else who is familiar with the method please take a crack at explaining it?

I speak the language of mathematics... please use words like coplanar, parallel, perpendicular, acute angle, right angle, etc etc.

Or even better yet, simply give an example of the coordinates of the top and bottom of the broomstick, and of the person's eye (while he/she is laying on the ground) in an XYZ Cartesian coordinate system where the XY plane is the ground and the Z axis is vertically upward, and the tree's base is at the origin.

Thank you!


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RE: measuring tree height

OK, I tried the PVC pole method to measure my test tree.

Pole height 10'0.5"
mirror to pole 17'10"
mirror to tree 64'8"

tree height = 10'0.5"/17'10" * 64'8" = 36.4'

...just a tad shorter than the other 3 methods described earlier.

It was a bit windy which made it a bit difficult to keep the pole perfectly balanced vertically, and to line up with the top sprouts of the tree. I may try again on a calmer day.


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RE: measuring tree height

Erased: my comments were too much.

Dax

This post was edited by gardener365 on Thu, Jul 31, 14 at 18:34


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RE: measuring tree height

> lay on the ground
> with your arm extended a few feet away from the base of the tree

If there's someone reading who understands Dax's broomstick method, would you please take a try at explaining it in a different way? Thank you.


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RE: measuring tree height

Ken, I am 43 yrs old. I got the term BIG TREE PROGRAM from online, searching several states databases to see several oaks pics at maturity, so likely some states use older terms than others. To anyone reading this, I haven't contacted anyone from Pa Big trees. It seems like most of the peeps who measure most of these trees are in the eastern half of the state. The few champs in my area, I haven't been able to find. I have no GPS. I am within feet of them, by the directions on the Pa big trees site, but can't find them. My friend has a GPS in her car, I'll have to wait until she isn't busy, and pester her. I think that the shovel, or object of known height from a distance as to include the whole tree is the best method for me. I am a learn by experience person, not by reading directions, I never had algebra in school. If I can see a phone number for the 2 trees closest to me in the Pa big trees program, I'll call, but I think there wasn't one, or I would have before.


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RE: measuring tree height

> Posted by tropicbreezent
> Wed, Jul 23, 14 at 0:56
> A piece of string is run out from the tube to the ground
> (at the same angle as the tube - 45 degrees).

I like this method.

I found it easier (and more accurate) to just look through the straw (I used a straw instead of a cardboard tube) in the opposite direction, to locate the point on the ground.

Pro: Only one person required.

Con: Moving and re-leveling the tripod is tedious if done with care sufficient to get a good reading. For some tree shapes, may not be possible to see top sprouts at 45 degree angle.


> Posted by grubby_me Tucson AZ 9
> Sun, Jul 27, 14 at 20:06
> Use a ten foot piece of pvc pipe...
> A mirror on the ground can substitute for sticking your eyeball on the ground.

I like this method a lot.

Pro: It's very quick and easy. Can measure over a range of distances.

Con: Requires a helper to hold the pipe.

This comes in very handy:


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RE: measuring tree height

  • Posted by SC77 6b (My Page) on
    Wed, Jul 30, 14 at 20:14

This might be dumb...but, why not get a helium balloon or two, attach long string, let rise to the height of tree an then mark the string...bring ballon down, measure string...rise & repeat. Only problem is wind or dense forest canopy


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RE: measuring tree height

> SC77 6b Wed, Jul 30, 14 at 20:14 wrote:
> ...helium balloon...

Now that's thinking outside the box. Clever.

And yes, it would have to be a *very* calm day. Zero wind.

.


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RE: measuring tree height

  • Posted by whaas 5a SE WI (My Page) on
    Wed, Jul 30, 14 at 20:30

SC77 idea is the winner...how straight forward and easy is that?

Just have to have patience!


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RE: measuring tree height

In geometry class, the teacher taught how to find the height of a tree or any vertical pole from the shadow.
It is basic geometry but I forgot how to do it.
Are there any math teachers on the forum?


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RE: measuring tree height

> lucky123 7 Wed, Jul 30, 14 at 20:38 wrote:
> ...how to find the height of a tree from the shadow

Read my earlier post in this thread dated Wed, Jul 23, 14 at 19:33. Method2.


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RE: measuring tree height

SC77, you are a friggin genius. The ultimate dummies way to measure tree height. I will try it. The Dollar tree has $1.00 helium balloons. I am pretty sure they are $1.00 anyway. You are a genius for this simple method.


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RE: measuring tree height

Glue two drinking straws to a piece of cardboard at a 45 degree angle with their ends about 2 inches or so apart.

Hold the cardboard up to your eye so that you can see through each straw just by moving your eye up and down without moving the cardboard.

Walk toward the tree until you can see the top and bottom of the tree through the top and bottom straws, respectively.

Pace off the distance "d" from the tree. "h" is the height of your eye above the ground (your height minus 4 or 5 inches).

Punch those values for "h" and "d" into the scientific calculator app on your smart phone. That's the height of the tree.

Note that the limit of the expression as "h" approaches zero is simply "d", so if you want to lay on the ground and look through the straws you can avoid the calculator in case you're allergic to them.

This post was edited by tenacre on Thu, Aug 7, 14 at 9:52


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RE: measuring tree height

I keep forgeting to go to the Dollar tree, but I am going to try the helium ballon method. I will need some rope or sisal twine from Dollar tree also.


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RE: measuring tree height

I know nothing about trees. I have a sunroom that total Sun all day. I would like to plant a tree that has a lot of shade. However I don't know what to buy. Can someone suggest a tree that gives shade.


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RE: measuring tree height

.
Hi Mrainey. You posted in the wrong thread. This thread is about measuring tree height.

Try creating a new thread for your question. If you need help, try reading the posting FAQ. If you still can't figure it out, come back here and ask, and I'll try to walk you through it.


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RE: measuring tree height

Mrainy, I want one of those. I would love to grow plants in the winter. Houseplants of course, but I want one, gotta play the lottery more often.


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