[lug] OT: android elevation app accuracy

Sat Oct 5 07:32:53 MDT 2013

Very cool!
I'll probably have to wait to long to buy such a thing at home depot, though....

On Fri, Oct 4, 2013 at 10:25 PM, Aaron Martin <cucheshire at gmail.com> wrote:
> This solution for measuring heights probably relied on linux in some way:
>
> Measuring Height by Connecting Clocks
>
> http://www.sciencedaily.com/releases/2013/10/131002103036.htm
>
>
>
> On Thu, Oct 3, 2013 at 9:22 AM, Davide Del Vento
> <davide.del.vento at gmail.com> wrote:
>>
>> Carl,
>> This is very kind of you. I'd like to try it. That sounds much easier
>> to use than a couple of buckets and garden hoses on their own. I can
>> certainly use the hose for extension if needed.
>>
>> Are you going to the next BLUG meeting? I'm not gonna use it before
>> then (otherwise I'll have to switch the subject of my flash talk from
>> email to leveling :-)
>> If you are not planning to go, I can go to your place and pick it up
>> (sometimes after the BLUG meeting)
>>
>> For making it Linux related, we may use the mic, detect the beep,
>> create a text file from that and use grep/sed/awk to find the actual
>> elevation... Or something like that...
>>
>> Thanks,
>> Davide
>>
>>
>> On Mon, Sep 30, 2013 at 5:52 PM, Carl Wagner <carl.wagner1 at gmail.com>
>> wrote:
>> > Davide,
>> >
>> > I am with John on this.  A water level with a helper or a
>> > transit/builders
>> > level could probably get you to 1/4" (abound 6 mm) or possibly better .
>> > How far apart are the corners?   I have a one person water level that I
>> > could loan you (it beeps when the water level on the remote end is at
>> > the
>> > same height as the sensor).    I think the hose is 50' long and it can
>> > be
>> > extended with a garden hose but you would need to buy the hose adapters
>> > from
>> > a place like Home Despot or McGuckin's (I "think" it is 3/8" clear
>> > plastic
>> > tubing so you would need a male hose to 3/8" barbed and a female hose to
>> > 3/8" barbed. Plastic adapters would work fine and are cheap.).  As
>> > others
>> > have said, make sure you get all the larger bubbles out.
>> >
>> > http://www.physicsforums.com/showthread.php?t=182965
>> >
>> > I am coming up with a blank on how to make this Linux related though.
>> > ;-)
>> >
>> > Carl
>> >
>> >
>> >
>> >
>> > On 09/30/2013 11:33 AM, John Hernandez wrote:
>> >>
>> >> Davide, use a string level or water level to establish a level
>> >> reference line.  Corners and other limitations may require you to
>> >> establish new points of reference as you proceed, but it shouldn't
>> >> take more than 15 minutes to go around the whole house with a helper.
>> >> An easy way to measure deltas is to create a story pole with a scrap
>> >> of lumber.
>> >>
>> >> It's also good idea to double check bubble or laser levels using the
>> >> water & tubing method described in other posts.
>> >>
>> >> On Mon, Sep 30, 2013 at 9:03 AM, Davide Del Vento
>> >> <davide.del.vento at gmail.com> wrote:
>> >>>
>> >>> Thanks for all these suggested (which of course I knew already, being
>> >>> a physicist by training.
>> >>>
>> >>> They are all very unpractical for what I need to do, because the
>> >>> corners are opposite and not in sight, the gutter is not level (and
>> >>> has a large "gap") and there is lots of additional small tricky
>> >>> details. The only feasible technique would be the bucket with the
>> >>> hose, but by no means easy or quick.
>> >>>
>> >>> Regarding the joke, that was probably true in the old times, but now
>> >>> things are different. Air pressure is about 84kPa at our altitude and
>> >>> here there is a differential of about 1kPa every 100m (330 ft).
>> >>>
>> >>> A barometer such as this http://www.omega.com/pptst/HHP360.html claims
>> >>> to be able to measure 0.015% or 0.01kPa or 1m (3ft) of ABSOLUTE
>> >>> pressure. So it can certainly measure the height of a building even if
>> >>> it's not as tall as a skyscraper! It can't go down to inches as
>> >>> absolute pressure, but maybe it can go there for relative one, which
>> >>> is what I need. However it's too expensive to try (or even spending
>> >>> time reading its specs to understand).
>> >>>
>> >>> According to http://what-if.xkcd.com/64/ an Android device is able to
>> >>> measure the pressure difference between head and feet of a person, so
>> >>> that's why I asked here in the first place: maybe it can measure an
>> >>> inch. Has anybody tried?
>> >>>
>> >>> Thanks!
>> >>> Davide
>> >>>
>> >>> On Sun, Sep 29, 2013 at 4:48 PM, Bear Giles <bgiles at coyotesong.com>
>> >>> wrote:
>> >>>>
>> >>>> Actually I just remembered a second approach. If you can run a hose
>> >>>> between
>> >>>> two buckets of water you can use it as a level. You'll need to make
>> >>>> sure
>> >>>> that the hose is completely full so the water can freely flow between
>> >>>> the
>> >>>> buckets but other than that it's a matter of putting the buckets on
>> >>>> each
>> >>>> corner of the building and figuring out a way to measure the height
>> >>>> of
>> >>>> the
>> >>>> water to what you're trying to check.
>> >>>>
>> >>>>
>> >>>> On Sun, Sep 29, 2013 at 4:40 PM, Bear Giles <bgiles at coyotesong.com>
>> >>>> wrote:
>> >>>>>
>> >>>>> This reminds me of the old physics major joke about how you
>> >>>>> determine
>> >>>>> the
>> >>>>> height of a skyscraper with a barometer.
>> >>>>>
>> >>>>> A: find the building super and tell him you have a neat barometer
>> >>>>> for
>> >>>>> him
>> >>>>> if he tells you the height of the building.
>> >>>>>
>> >>>>> You'll need a level. A barometer isn't going to cut it, not even
>> >>>>> remotely.
>> >>>>>
>> >>>>>
>> >>>>> On Sun, Sep 29, 2013 at 4:35 PM, Jed S. Baer <blug at jbaer.cotse.net>
>> >>>>> wrote:
>> >>>>>>
>> >>>>>> On Sun, 29 Sep 2013 16:28:03 -0600
>> >>>>>> Jed S. Baer wrote:
>> >>>>>>
>> >>>>>>>> i.e. how much slope there is, if any,
>> >>>>>>>> between these two corners
>> >>>>>>>
>> >>>>>>> I think your best bet will be to use a string level. Or, a 4 foot
>> >>>>>>> or
>> >>>>>>> longer beam level, working along your gutter.
>> >>>>>>
>> >>>>>> Or,
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>> http://www.homedepot.com/p/Johnson-Hand-Held-Sight-Level-80-5556/202911589
>> >>>>>>
>> >>>>>>
>> >>>>>> http://www.homedepot.com/p/Johnson-Torpedo-Laser-Level-40-0915/202258085
>> >>>>>>
>> >>>>>> Might be you know someone who has a laser level already?
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>> >>>>
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