Estimating height

[+OK-Pogo Buddies]

I have been to two EarthCaches that ask me to submit the estimate height of the bluff etc as proof. I am lost as to how to do this with my gps, if I am at the posted coordinates (which is one of the proofs needed) and just looking at the cache from a distance. Can anyone help?

[+Rev Mike]

I have been to two EarthCaches that ask me to submit the estimate height of the bluff etc as proof. I am lost as to how to do this with my gps, if I am at the posted coordinates (which is one of the proofs needed) and just looking at the cache from a distance. Can anyone help?

 

Does not sound like you need to do anything with your GPS.

I would simply take the best guess that I could since that would be an estimate.

 

Could you perhaps reference the two listing you ask about?

 

- Rev Mike

[+OK-Pogo Buddies]

Does not sound like you need to do anything with your GPS.

I would simply take the best guess that I could since that would be an estimate.

 

Could you perhaps reference the two listing you ask about?

 

- Rev Mike

 

I am useless at estimating heights, so thought there must be some trick using the GPS to estimate.

 

Here are the two listings.

GC17NQD - Naramata Silt Bluff

GC17NQF - McIntryre Bluff

[+OK-Pogo Buddies]

-

Edited October 20, 2008 by vertek001

[+Rev Mike]

I am useless at estimating heights, so thought there must be some trick using the GPS to estimate.

 

Here are the two listings.

GC17NQD - Naramata Silt Bluff

GC17NQF - McIntryre Bluff

 

The only real trick to using the GPS that I know of is to note the elevation at both the top and the bottom and find the difference... but that is not what is asked for... just an estimate. Also now that I have seen the listings I can see that these are not features you want to climb for a reading and the owner even says not to. Just take a guess if the owner was looking for anything more then that would be noted. An estimate is all he asks for so - if it is something reasonable and the other requirements are completed that should be good.

 

But here is a trick NOT using the GPS - click on the map at the bottom of the page and then click on the topo tab in the top right corner. Compare the elevation you see on the map with the reading you were required to get at the bottom and that will be a very good estimate.

 

Hope that helps.

 

- Rev Mike

Edited October 20, 2008 by Rev Mike

[rogheff]

Find yourself a First Class Boy Scout and ask him how to estimate the height of that bluff.

[+Lostby7]

Find yourself a First Class Boy Scout and ask him how to estimate the height of that bluff.

Leave it to Roger to bring the Scouts into it.... I did a quick search on Scout techniques for measurement and found this:

Pencil Method: A simple method for measuring the height of trees and ordinary buildings is the Pencil Method. Standing some 25 yards or meters from the tree, with a pencil or stick held upright in the fully extended hand, first move the thumb up the stick until the exposed length covers, to your eye, the lower two yards or meters of the tree (the height of a man). Now move hand and pencil up in two yard or meter jumps till the top is reached. Multiply the jumps by six and add any odd yards or meters left at the top. To get the height of a building a rapid method is to calculate the height of a story, and multiply by the number of stories.

 

[+BilboB]

I have a similar requirement on one of my Earthcaches in Vermont. It asks you to estimate the size (length) of a sand dune. I know the answer already, but it is more for the cacher to at least try and determine the length, more than arriving at a specific answer.

[rogheff]

Find yourself a First Class Boy Scout and ask him how to estimate the height of that bluff.

Leave it to Roger to bring the Scouts into it.... I did a quick search on Scout techniques for measurement and found this:

Pencil Method: A simple method for measuring the height of trees and ordinary buildings is the Pencil Method. Standing some 25 yards or meters from the tree, with a pencil or stick held upright in the fully extended hand, first move the thumb up the stick until the exposed length covers, to your eye, the lower two yards or meters of the tree (the height of a man). Now move hand and pencil up in two yard or meter jumps till the top is reached. Multiply the jumps by six and add any odd yards or meters left at the top. To get the height of a building a rapid method is to calculate the height of a story, and multiply by the number of stories.

 

 

My favorite is the "old indian" method. It isn't terribly accurate, but it sure is fun to watch.

 

You stand with your back to the object you want to know the height thereof. You bend over until your head touches the ground. When the top of the object is at the point in your jeans where the seams meet (crotch) you are the correct distance from the object. You will have to move back and forth numerous times to get this distance correctly (and do the bend-over thing many times).

 

Now you simply pace off the number of steps from your current location to the object. 75 paces = 75' tall.

 

It's a lot of fun watching all these kids (and parents ) stooping over to plop their heads on the ground, getting dizzy and tumbling. In the end, they all love me for suggesting it

[+Renegade Knight]

I have been to two EarthCaches that ask me to submit the estimate height of the bluff etc as proof. I am lost as to how to do this with my gps, if I am at the posted coordinates (which is one of the proofs needed) and just looking at the cache from a distance. Can anyone help?

 

I cant' estimate height or distance. But I can guestimate. If the tree's are about 20' tall. How many tree's tall is the cliff? That I can do. Then if it's 10 trees tall that's 200 feet.

[XC_Tracker]

You could always use some simple Trigonometry. SOH CAH TOA!!!

[XC_Tracker]

You could always use some simple Trigonometry. SOH CAH TOA!!!

 

*Edit* Amazing, I click submit once, but it posts twice. Simply stunning.

Edited October 23, 2008 by XC_Tracker

[+danieloliveira]

Besides all the (valid) methods already proposed, I like to guesstimate by comparison.

The best comparison that I see is knowing that each floor of a building is approximately 3 metres high. Therefore a 5 level building will be 3x5 m=15 m. When you use methods like this you immediately limit overexageration.

[+ThatPoshGirl]

1. Get a protractor. It should have a hole where the 90 degree line crosses the straight line along the flat edge. If it doesn't you will need to add one.

 

2. Glue or tape a straw or some other type of tube along the straight edge.

 

3. Tie a piece of string to the protactor through the hole. If the string is the right thickness you can just pass the string through the hole and then tie a knot in the string to secure it. Tie a weight of some type, i.e. a fishing lure, to the other end of the string.

 

4. Measure the soles of your boots/shoes. For instance the sole on my hiking boot is exactly 11".

 

5. Stand at the base of the object you are estimating. Walk away from it and count your paces. How far you walk will depend on how tall the object is, just use your judgement. Multiply the number of paces by how many inches your soles are. So, if I walked 20 paces I would multiply 20x11 and know I am roughly 220 inches from the object. Write it down, d=220 (or whatever).

 

6. Now hold your protractor (makeshift clinometer) with the flat side up. Look through the straw or tube and sight the top of the object. Without moving your clintometer look at the markings and see where the string crosses (or have a friend do it for you if that is easier). Whatever number that is, subtract 90 from it. You now have an angle of elevation from your eyeline to the top of the object. Write it down, A=30 (orwhatever).

 

5. Do the math. Our good friend Sohcahtoa tells us that height from your eyeline to the top will be d*tan(A), in the above example 220*tan(30). (You did bring a scientific calculator with you, right?)

 

7. Almost done. Since this is the height from your eyeline up, you have to add in the height from the ground to your eyeline. Just add you own heigh minus 2 or 3 inches.

 

Done! So, again: d*tan(A)+(h-3)

 

Of course, this is only as accurate as the ground is level. If the terrain is relatively flat you will get a fairly accurate estimate. If the terrain is sloping your estimate could be off quite a bit. You can estimate the angle of the slope of the ground (still using your clinometer), but then it gets a little more complicated. And I really need to be able to draw a picture to explain that one.

 

If you forgot your scientific calculator you could always estimate the function with a taylor polynomial

[+Juicepig]

I am 2m tall - I just visualize myself stacked toe to head, and take measurements that way.

 

Pretty accurate if you are good at spacial orientation

[+OmegaLimit]

1. Get a protractor. It should have a hole where the 90 degree line crosses the straight line along the flat edge. If it doesn't you will need to add one.

 

2. Glue or tape a straw or some other type of tube along the straight edge.

 

3. Tie a piece of string to the protactor through the hole. If the string is the right thickness you can just pass the string through the hole and then tie a knot in the string to secure it. Tie a weight of some type, i.e. a fishing lure, to the other end of the string.

 

4. Measure the soles of your boots/shoes. For instance the sole on my hiking boot is exactly 11".

 

5. Stand at the base of the object you are estimating. Walk away from it and count your paces. How far you walk will depend on how tall the object is, just use your judgement. Multiply the number of paces by how many inches your soles are. So, if I walked 20 paces I would multiply 20x11 and know I am roughly 220 inches from the object. Write it down, d=220 (or whatever).

 

6. Now hold your protractor (makeshift clinometer) with the flat side up. Look through the straw or tube and sight the top of the object. Without moving your clintometer look at the markings and see where the string crosses (or have a friend do it for you if that is easier). Whatever number that is, subtract 90 from it. You now have an angle of elevation from your eyeline to the top of the object. Write it down, A=30 (orwhatever).

 

5. Do the math. Our good friend Sohcahtoa tells us that height from your eyeline to the top will be d*tan(A), in the above example 220*tan(30). (You did bring a scientific calculator with you, right?)

 

7. Almost done. Since this is the height from your eyeline up, you have to add in the height from the ground to your eyeline. Just add you own heigh minus 2 or 3 inches.

 

Done! So, again: d*tan(A)+(h-3)

 

Of course, this is only as accurate as the ground is level. If the terrain is relatively flat you will get a fairly accurate estimate. If the terrain is sloping your estimate could be off quite a bit. You can estimate the angle of the slope of the ground (still using your clinometer), but then it gets a little more complicated. And I really need to be able to draw a picture to explain that one.

 

If you forgot your scientific calculator you could always estimate the function with a taylor polynomial

 

I have a problem with step 3 in your algorithm. You are assuming that you can get to the base of the object that you are measuring.

 

I've been planning an EarthCache where you measure the elevation of a radio tower on the top of a hill from the bottom of the hill. You could never legally hike to the top of the tower to get a GPS reading of the elevation, but you can measure it from a nearby parking lot using a similar procedure to yours.

 

Then, one only has to take two measuremets and solve an ASA triangle. I would explain every step. But then again, when ever I hand out a math test, I always say, "I didn't intend to make this hard."

Edited December 22, 2008 by OmegaLimit

[+ThatPoshGirl]

 

I have a problem with step 3 in your algorithm. You are assuming that you can get to the base of the object that you are measuring.

 

I've been planning an EarthCache where you measure the elevation of a radio tower on the top of a hill from the bottom of the hill. You could never legally hike to the top of the tower to get a GPS reading of the elevation, but you can measure it from a nearby parking lot using a similar procedure to yours.

 

Then, one only has to take two measuremets and solve an ASA triangle. I would explain every step. But then again, when ever I hand out a math test, I always say, "I didn't intend to make this hard."

 

Certainly there are plenty of scenarios where things will not be so straight forward. I was just trying to give the basic concept. I figure people can work it out from there.

[+Indotguy]

I've estimated height of bluffs etc. as follows. I stand against the bluff at its base and either take a digital photo remotely or mark somehow where the top of my head falls on the bluff and then move away from the bluff and take a photo, making sure to get the entire height of the bluff in the frame. Back at the PC I open the photo file using "Paint" and draw a vertical line next to my figure in the photo. Since I know how tall I am, I can estimate the height of the bluff by copying and pasting the line, end to end, until I reach the top. A count of the number of vertical line segments from base to top multiplied by your height and you have a fairly accurate estimate.