Clinometer Errors and Calibration

General discussions of measurement techniques and the results of testing of techniques and equipment.

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dbhguru
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Re: Clinometer Errors and Calibration

Post by dbhguru » Thu Jan 24, 2013 11:22 am

Ed, Karlheinz, et al.,

Please look at the third spreadsheet of the attached Excel workbook. Karl, this creates a simple format for trying different combinations of height, base, and angle error. The data in the light green cells can be over-typed with new data. However, the spreadsheet was designed around heights of 0,50,75, and 100 meters against a common baseline and common angle error. That convention should be maintained. Of course, the spreadsheet reinforces what you've shown, Karl.

Bob
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Karlheinz
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Re: Clinometer Errors and Calibration

Post by Karlheinz » Thu Jan 24, 2013 6:21 pm

Bob, Ed,
I am very pleased that you can confirm my calculation and that we have come to matching results.
What I have summarized in one formula that gives you, Bob, in manageable sub-steps in the Excel spreadsheet.

Karl

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Matt Markworth
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Re: Clinometer Errors and Calibration

Post by Matt Markworth » Sun Jan 31, 2016 2:36 pm

NTS,

I encourage anyone with a clinometer to run the test described by Ed in this thread: http://www.nativetreesociety.org/measur ... esting.htm.

Bob also created a really nice illustration with an accompanying formula, which appears earlier in this thread. I have included it here as well:
clinometer%20error2.GIF
I ran this test with my Suunto clinometer recently. I used two white poles (goal posts on two football fields that are next to each other) and blue painter's tape to mark the poles. The poles make it very easy to hold the clinometer steady. The two poles are 84.4 meters apart. Having poles at a far distance like this is helpful because it will be easier to uncover if the clinometer is reading high or if it's reading low. Although, you don't want the poles too far apart because then it becomes harder to see the target.

I placed blue tape at eye level on the first pole and shot to the second pole. Blue tape was placed on the second pole where the clinometer read 0 degrees. I went to the second pole and placed the clinometer next to the blue tape and shot back to the first pole and found the place on the pole that read 0 degrees. The 0 degrees reading corresponded with the blue tape, so my Suunto is dead level. Because it's a mechanical device with the weight of the wheel always pointing down, it should also be accurate at all angles. I think that testing an electronic clinometer in a similar manner is also a good idea, although errors in an electronic clinometer can vary depending on the steepness of the angle. In my case, comparing an electronic clinometer to the Suunto serves as a good test at various angles.

If you shoot back to the first pole and 0 degrees is somewhere different than the blue tape, then add a second piece of blue tape to the pole wherever the reading is 0 degrees. If the second piece of blue tape is below the first, then the clinometer reads high. If the second piece of blue tape is above the first, then it reads low. The error can be found by measuring the distance between the poles, the distance between the two tape marks on the first pole, and using Bob's formula.

Matt

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