[lug] OT: android elevation app accuracy

Thu Oct 3 08:22:45 MDT 2013

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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