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<p>Hi</p>
<p>Been figuring out how to do this for a while - my solution-</p>
<p>rule - I used 30cm (aka 1 foot), calculator, known length of arm
- in my case .6m, OSM map to measure distance from target.<br>
</p>
<p>With hand holding rule vertically measure the target height
against the rule for rule height, this is the key measurement,
note the measurement point. From the map measure the distance from
the measuring point to the target<br>
</p>
<p>With this information and using proportions (which is what a
tangent is) - <br>
</p>
<p>target height = (rule height in metres * distance from measuring
point to target) / length of arm in metres.</p>
<p>Using this technique I have this morning measured known height of
of a local landmark, and the unknown height of a building. The
known height of 50m measured 8cm at a range of 375m. The unknown
height of the building with 5 floors was calculated to be 20.7
metres which would on the face of it be realistic (from 3cm and
414m). (Botany Bay mill in Chorley).<br>
</p>
<p>TonyS999<br>
</p>
<div class="moz-cite-prefix">On 19/03/2019 09:30, Brian Prangle
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAECtZzC6kxfvE=xYp1PrxXA-GiKjBKryxrW--_-5zJO_O2TKMA@mail.gmail.com">
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<div dir="auto">There are also theodolite apps for smartphones</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, 19 Mar 2019, 00:17 Rob
Nickerson, <<a href="mailto:rob.j.nickerson@gmail.com"
moz-do-not-send="true">rob.j.nickerson@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="auto">For building heights why not try using a laser
measure? Those with a Pythagoras Measurement mode should
automate the calculations for you.
<div dir="auto"><br>
</div>
<div dir="auto">Price has fallen a lot over the years. Seems
like even a basic £30 device is sufficient.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Best regards,</div>
<div dir="auto">Rob</div>
</div>
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