[lug] OT: android elevation app accuracy

Fri Oct 4 22:25:25 MDT 2013

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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