Beth
Outstanding! Actually, Don Bertolette has developed a sighting
device for the iPhone clinometer.
Bob
Sent from my iPhone
On Dec 22, 2009, at 6:57 PM, Beth <[email protected]> wrote:
> A Small Comparison between Suunto and iPhone Clinometers
>
> Since some of us now have iPhones and have downloaded the
> Clinometer application I thought that someone needs to compare the
> iPhone to the Suunto clinometer. Today I took 14 measurements each
> while sitting on my couch to a ceiling heating/AC vent. I then
> measured my eye height, the ceiling height, and the distance from my
> eyes to the tape measure hanging from the vent as a plumb bob. These
> measurements were: ceiling height = 96”, height of the eyes =
> 38”, and
> distance to the vent plum bob = 219”. I used the measurements to
> calculate the angle I was trying to measure with the Suunto and
> iPhone. Before taking my measurements I calibrated my iPhone
> clinometer according to the instructions. I also had the following
> settings: Fast approximation-on, Beep on lock-on, wait for lock
> accuracy of + 0.1o- all the way to the left (+ 0.1o), disable auto-
> lock-off, and 3D glass effect-on.
>
> The first thing that I do in order to calculate the angle A was to
> calculate the distance from my eye to the ceiling; 96”-38”= 58”.
>
> Since Tan A = a/b, we can rearrange the equation to find A by dividing
> both sides by Tan. Since 1/Tan =Arc Tan the equation is A = (a/b) Arc
> Tan. Filling in this equation with the data we get A = (58/219) Arc
> Tan or A = 14.8336707057. Taking signifiginte numbers in mind I am
> going to say the angle is 14.8o. (Note: I calculated this after
> gathering the data as not to influence the clinometer data)
>
> Now for the clinometer data:
> Suunto iPhone Suunto iPhone
> 15.5 15.2 14.5 15.4
> 15.0 14.9 15.0 15.2
> 15.0 15.1 14.5 15.2
> 15.0 14.1 14.5 15.1
> 15.0 15.0 14.5 15.7
> 15.0 15.2 15.0 15.5
> 14.5 15.1 14.5 15.2
> The means were 14.8 and 15.1 for the Suunto and iPhone respectively
> with standard deviation of 0.31 and 0.35.
>
> The one thing I noticed in my raw data is with the Suunto my highest
> and lowest angles were 15.5 and 14.5 whereas with the iPhone they were
> 15.7 and 14.1. I can think of at least two reasons why. 1) I have
> more experience with the Suunto than I have with the iPhone and 2) the
> Suunto has a line to help repeatly “hit” the same spot whereas the
> iPhone you are just looking down one side of the phone.
>
> I also noticed after calculating the angle (14.8) the Suunto average
> was closer than the iPhone’s (14.8 vs. 15.1). Now is 0.3o differen
> ce
> significant? Bob has more experience with the Suunto than I do and he
> has stated in the past that can read it to the nearest ¼ o. I myself
> can only read it to the nearest ½o. Given this I believe that a
> difference of 0.3o is.
>
> How can the iPhone be improved? If one would add a sighting device on
> to the iPhone this could help “hit” the same spot repeatly.
> Obviously
> this can not be same one that is used in the Suunto’s, looking throu
> gh
> it with an optical illusion. Maybe a tiny gun sighting built into the
> volume and/or ringer buttons on the left side. I think someone
> thought of this earlier. With the sight and practice I believe one
> could the angle down to the nearest tenth of a degree. With the
> Suunto one can only really estimate anything less than 1 degree.
> Beth
>
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