Pocket Rangefinder
 

"Zach @ Ze Dev"
. It allows you to measure the distance to far-away
objects by comparing an image on the Pocket PC held at arm's length to
the actual distant object. When parameters such as screen height and
arm length are entered, I've found the measured distance to be quite
accurate -- typically within 5%. Metric and US Customary units are
supported.

I've got two pocket rangefinders. One on the end of each arm.

My little finger subtends 1 degree when held at arm's length. My fist
subtends 5. My spread hand subtends 15.

Anyone can calibrate their hands to create an approximate rangefinder. Start
with the assumption that 1/60 is one degree (actually 1/57.9, but who's
quibbling in this approximate world). I hold my hand a convenient 30inches
away (my hand is that far from my eye if I stand a certain way). Anything
that's half an inch across subtends a degree. Easy.

I started with a ruler, then a bit of wood with wires sticking up, then
realised I was re-inventing an old fashioned sector stick. So I added
lightness and created simplicity by checking out my finger dimensions and
getting rid of the encumbrances. Lo and behold - all my crew have these
lightweight simple sextants.

Very useful for defining well camouflaged objects relative to some easily
identified feature. Like pointing out partially obscured leading marks.

For range finding you can either do the mental arithmetic (1/60 again,
knowing the height or breadth) or create a little general table. Which I
guess is what your software does.
--
Jim B, Yacht RAPAZ,
Summers in the Med, winters in UK
jim[dot]baerselman[at]ntlworld[dot]com