How to measure a tree radius so I can build a study model??


so i have to build a study model and having the PRECISE measurement of the tree radius is important.

I am completely clueless how I can go about doing this.


anybody can give me some serious tips?

Jul 6, 12 2:54 am

piece of string. tie it around the tree at the point you want to know the radius of. the total circumference is the length of string it takes to get around the tree. Then just rearrange this formula:

C/d = pi

where C is circumference, d is diameter (unknown) and pi is, well, pi.

the radius is half the diameter.

Jul 6, 12 4:15 am

I actually googled it and found the same result :)

Jul 6, 12 6:06 am

Why are you placing the designed object so close to the tree? Is it to model it supper accurately or are you worried about gaps and you want to cut the materials precisely up to the trunk?

I saw this done with disastrous effect for the deck and the tree.  A healthy tree can grow 1/8 to 3/8 inches in diameter each year and you can kill or injure the tree if you choke or girdle the trunk.  Trees also sway and need some room to move, depending on the soil and root structure the pivot point may be below grade.  But the situation I cite the deck was built and the first windstorm caused the tree to move and the decking to buckle, so the tree was tethered with cables, four years later the tree buckled the boards again, the trunk had grown, then a year later the tree was dead. Give the tree some room to move and have breakaway sections to accommodate trunk growth.  Also have your joist and beams out of the path the tree might take if it falls. Now if the tree is dead and is a structural column then disregard the comments above.


Over and OUT

Peter N

Jul 6, 12 11:44 am

Effective and environmentally friendly way to measure trees. 

Jul 6, 12 11:52 am

i need to make close/approximate measurements trees on a block because we're doing an art installation that will probably use the spaces between the trees, around the trees, etc.etc.etc.  

just having that will give us a better idea of how big our art installation can be. 

Jul 6, 12 1:22 pm

also can use a flat surface butted against the tree and 2 t-squares to get the diameter then just divide by 2.    -I---I-

figure it out!

Jul 6, 12 1:34 pm

If someone doesn't know how to measure a circumference and calculate a radious...ouch.

Instead of a string, you could also use a tailor's measuring tape.

Having said that, and since the question asked for a "PRECISE" measurement of a tree's radius, it might be worth noting that most trees are not precise circles in section.  When dealing with organic forms, you probably need to account for a bit of slack especially if the tree moves in the wind at all.

Good luck, yo!

Jul 6, 12 1:42 pm

A caliper is a tool that looks like a letter F that is used for that very thing!

Jul 6, 12 6:46 pm

so that guy up there is 'F'-ing that tree?

Jul 6, 12 7:09 pm

cut it down and 3d scan it uuuup!

yay technology. 

Jul 6, 12 7:50 pm

Measuring trees diameters is a little more complicated than making giant calipers from t-squares or applying simple geometry since most trees aren't really round...

Tree Diameters are measured at 'Breast Height' aka DBH aka 4.5' (1.37m) off the ground when there is just one trunk...

Typically a special tape measure is used, or a set of calibrated calipers out in the field. But then why do you need to be that precise for a model?

Jul 6, 12 10:01 pm

Barry that's a very helpful chart!  But some breast heights are higher than others.

Jul 6, 12 10:18 pm

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