Joe, list:
I had to figure-out how to count the digitized pixels (and assign a size to
them)
years ago with infrared thermal images. It wasn't very easy then (until the
software
authors started packaging-in the tools). Have you figured-out how to do it
with one
of the photography software packages? (I haven't used those much, myself.)
Between my first "cave-man" approach (laying square-grid mylar drafting media
on a
light table over the images, and counting squares-- like someone has already
mentioned)-- and the time I finally learned how to get pixel counts from the
digital
image files-- I discovered a neat old tool called a "polar planimeter". It's
kind of
a contraption to set-up-- but, once done-- you trace the outline of your
picture, and
the planimeter mechanically integrates the area within your trace, providing
you with
a fairly accurate result! I looked in my closet and found that I still had one
(under
a pile of slide-rules). It should be a piece-of-cake to get frontal area of a
car
from a good, square-on frontal photo (taken with a camera lens w/o much
spherical
abberation). I'd be glad to try it, if somebody can supply a good picture (and
one
accurate linear measurement, to establish the scale).
Russ Mack
Joe Amo wrote:
> I have also heard of taking a frontal picture
> digitizing it, then just add up the pixels
>
> Joe :)
>
> Ed Van Scoy wrote:
>
> > Your "method" is pretty much the same as the one suggested to me by
>"Flowbench";
> > he suggested scaling the car on graph paper. and as you mention, count the
> > squares.
> > Ed
> >
> > DrMayf wrote:
> >
> > > I still have to have some secrets, don't I? Actually, can't be derived by
> > > me, gotta measure it or find a good number. The Cd tables in the web site
> > > have an awful lot of them. SOme are bound to be close. When I get ready to
> > > do mine, I will find the lowest, widest, tallest points on the car and
>use a
> > > fixed stanchion to measure from. This will make a composit outline of the
> > > car, psuedo cross section, if you will. I'll scale that down and count the
> > > little squares inside the outline. Probably a lot harder to do than saying
> > > it. Now, I've been know to hang around Keith's trailer, so are you
> > > implying something or another here? And Dave is the one who watches the
> > > cooler...
> > >
> > > and yes Virginia, I doknow what slugs are....
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