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    Re: Estimating height of eye
    From: Brad Morris
    Date: 2013 Apr 10, 11:25 -0400

    Hi Marcel

    There is an app in the Android market called "Precision GPS Pro".  The cost is US$0.99 

    It claims a 1 meter elevation accuracy after averaging, although they do not indicate how long an average you require to achieve that.

    The free version of this app does not do elevation averaging.

    I have not tried this app.

    Brad

    On Apr 9, 2013 6:21 AM, "Marcel Tschudin" <marcel.e.tschudin---.com> wrote:

    In my sunset observations the guesstimates for the HoE of probably not
    better than +/- 20% are indeed a weak point. But how weak? The dip is
    proportional to the square root of the HoE which means that the
    estimated dip error is only half of the estimated HoE error. For the
    average HoE of 3.5m the "normal" dip is 3.3 moa and a 10% error of it
    therefore +/- 0.33 moa. This corresponds in the photo to slightly more
    than one pixel which is 18 seconds of arc.
    
    Frank, you mentioned estimating HoE within about +/-5%. I'm wondering
    whether you would also be able to attain such an accuracy by climbing
    over the rocks as shown in my photo:
    https://mail-attachment.googleusercontent.com/attachment/u/0/?ui=2&ik=b33d2c81ba&view=att&th=13ddab531282f2e7&attid=0.1&disp=inline&realattid=f_hf5h7cfp0&safe=1&zw&saduie=AG9B_P-DvbGAuAxTxtruQd29-avq&sadet=1365502394438&sads=w4N-7jPt0vbdfN6eZHKSEaR8vQ0
    For my average of 3.5 m this would correspond to less than 20 cm or
    what might be more familiar to you to about half a foot.
    
    In order to verify my guesstimates I do indeed consider to perform
    some additional measurements. I'm wondering how good I could measure
    it using GPS and also the Russian version of it. I have no experience
    in using these systems. I understand that I would have to measure both
    levels, eye and sea level and then take the difference. Is there an
    Android application which I could load on my Samsung pad allowing to
    collect measurements over a longer time period which then calculates a
    mean altitude and its standard deviation? What are the sort of result
    one could obtain this way?
    
    Marcel
    

    View and reply to this message: http://fer3.com/arc/m2.aspx?i=123477

       
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