harry k wrote in
:

On Oct 8, 9:19*am, bud-- wrote:
Mike Paulsen wrote:
SteveB wrote:
How do I figure the area of a pool from the perimeter? *It is a
kidn
ey
shaped (exaggerated) pool.

Steve

1. Measure the perimeter. Write it down on a scrap of paper. Throw
the paper away.

2. Find your pool on google earth or google maps satellite view.

3. Print it, being sure to include something in the print which is
easy to measure. (deck, section of fencing, etc.)

4. Weigh the print.

5. Carefully cut out the pool. Weigh the pool

6. Using the actual length of the easy to measure object, determine
the area represented by the entire print.

7. Fill in:

mass of pool cutout * * * * area of pool (unknown)
------------------- * *= * * --------------------
mass of entire print * * * *area of entire print

8. Do the math: (mass of pool) * (area of entire print) / (mass of
entire print) = (area of pool)

It is an exact answer.

Errm...wouldn't you have to allow for the weight of ink in various
areas?


My exact answer is pour 55 gallons of motor oil in the pool (perhaps
0W20
).

The oil, of course, floats. Measure the thickness of the oil layer.
Since you know the thickness and the volume, determining the area is
trivial.

--
bud--- Hide quoted text -


Nice. dunno about this: Drop good sized weight in, measure
difference in water level...

You mean like one of those 300lb K-Mart Babes?


Harry K

On Oct 9, 7:33*pm, Red Green wrote:
harry k wrote :





On Oct 8, 9:19*am, bud-- wrote:
Mike Paulsen wrote:
SteveB wrote:
How do I figure the area of a pool from the perimeter? *It is a
kidn
ey
shaped (exaggerated) pool.

Steve

1. Measure the perimeter. Write it down on a scrap of paper. Throw
the paper away.

2. Find your pool on google earth or google maps satellite view.

3. Print it, being sure to include something in the print which is
easy to measure. (deck, section of fencing, etc.)

4. Weigh the print.

5. Carefully cut out the pool. Weigh the pool

6. Using the actual length of the easy to measure object, determine
the area represented by the entire print.

7. Fill in:

mass of pool cutout * * * * area of pool (unknown)
------------------- * *= * * --------------------
mass of entire print * * * *area of entire print

8. Do the math: (mass of pool) * (area of entire print) / (mass of
entire print) = (area of pool)

It is an exact answer.

Errm...wouldn't you have to allow for the weight of ink in various
areas?

My exact answer is pour 55 gallons of motor oil in the pool (perhaps
0W20
).

The oil, of course, floats. Measure the thickness of the oil layer.
Since you know the thickness and the volume, determining the area is
trivial.

--
bud--- Hide quoted text -

Nice. *dunno about this: *Drop good sized weight in, measure
difference in water level...

You mean like one of those 300lb K-Mart Babes?





Harry K- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

Now how did you know about my GF?

Harry K

mike wrote:
On Oct 8, 2:25 pm, E Z Peaces wrote:
E Z Peaces wrote:
SteveB wrote:
How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.
Steve
The skimmer on my neighbors' pool has a throat 145mm high. If I put the
end of a white plastic ruler against the bottom of the throat, the ruler
looks bluish below the waterline and pinkish above. This makes it easy
to read the depth of water in in the throat with a precision greater
than 1 mm.
Now see what units your water meter measures. Wait until the water is
near the bottom of the skimmer throat. Write your depth in mm. Write
your meter reading.
Fill. Write your new depth and meter reading. See how much water was
used and convert to liters. Divide that by mm to get square meters
within 1%.
Ideally, choose a windless, overcast day when the water temperature is
near the dew point.- Hide quoted text -

- Show quoted text -

Just out of curiosity, have any of you ever seen a pool where there
are absolutely no ripples and the water level isn't heaving even a
little from some sort of hydraulic pendulum effect?

I checked again to day. The owner had cleaned leaves from the skimmer
basket, so there was more rippling from the return jets. It looked like
1mm peak-to-peak in the skimmer throat.

Measuring at the bottom peaks gave repeatable results, but it wouldn't
work to measure a change in level at the skimmer with the pump going.
Water velocity would affect the reading, and the velocity in the skimmer
throat would slow down as the level in the skimmer rose.

It looks as if I couldn't guarantee to calculate the area of the pool
within 1% this way. I don't even know how accurate a municipal water
meter is. However, it requires only two ruler readings and two meter
readings, and the results could be accurate to 1% or so.

Now suppose it's a rectangular pool 5 x 10 meters, and your tape
readings are 1% high because of sagging of the tape and rounded edges on
the pool. Your calculation will be 2% too high. If in addition the
corners of the pool are rounded, the calculation will be more than 2%
too high. Even for a simple rectangle, it might be more accurate to
calculate area by measuring a change in depth of 100mm or so.

harry k wrote in
:

On Oct 9, 7:33*pm, Red Green wrote:
harry k wrote
innews:5048965a-f0bb-4444-bd5f-dd
:





On Oct 8, 9:19*am, bud-- wrote:
Mike Paulsen wrote:
SteveB wrote:
How do I figure the area of a pool from the perimeter? *It is a
kidn
ey
shaped (exaggerated) pool.

Steve

1. Measure the perimeter. Write it down on a scrap of paper.
Throw the paper away.

2. Find your pool on google earth or google maps satellite view.

3. Print it, being sure to include something in the print which
is easy to measure. (deck, section of fencing, etc.)

4. Weigh the print.

5. Carefully cut out the pool. Weigh the pool

6. Using the actual length of the easy to measure object,
determine the area represented by the entire print.

7. Fill in:

mass of pool cutout * * * * area of pool (unknown)
------------------- * *= * * --------------------
mass of entire print * * * *area of entire print

8. Do the math: (mass of pool) * (area of entire print) / (mass
of entire print) = (area of pool)

It is an exact answer.

Errm...wouldn't you have to allow for the weight of ink in various
areas?

My exact answer is pour 55 gallons of motor oil in the pool
(perhaps 0W20
).

The oil, of course, floats. Measure the thickness of the oil
layer. Since you know the thickness and the volume, determining
the area is trivial.

--
bud--- Hide quoted text -

Nice. *dunno about this: *Drop good sized weight in, measure
difference in water level...

You mean like one of those 300lb K-Mart Babes?





Harry K- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -

Now how did you know about my GF?

Harry K


Well, don't forget our rubbers...and a bag of flour.

"SteveB" wrote in message
...

"John H. Holliday" wrote in message
...
"SteveB" wrote in message
...
How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.

Steve

2 ways --

1. If you have a good GPS unit, create a GPS track around the pool. The
GPS will have the algorithms to calculate the area.

2. Drain the pool. Determine the average depth. Calibrate the rate of
fill (time a garden hose to fill a measured container - 1 gal, 5 gal, or
something similar. Refill the pool, timing the refill. The timing tells
you how many gallons or how many cu. ft, depending on how you calibrated it.
Now you know the volume and can work back to the area.

Actually, I like the "draw it out on a piece of graph paper and count the
squares" method.

"JimR" wrote in message
...

"SteveB" wrote in message
...

"John H. Holliday" wrote in message
...
"SteveB" wrote in message
...
How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.

Steve

2 ways --

1. If you have a good GPS unit, create a GPS track around the pool. The
GPS will have the algorithms to calculate the area.

2. Drain the pool. Determine the average depth. Calibrate the rate of
fill (time a garden hose to fill a measured container - 1 gal, 5 gal, or
something similar. Refill the pool, timing the refill. The timing tells
you how many gallons or how many cu. ft, depending on how you calibrated
it. Now you know the volume and can work back to the area.

Actually, I like the "draw it out on a piece of graph paper and count the
squares" method.

A GPS that will count that short a distance, and calculate an area as small
as 500 square feet? I want one!

Steve

On Sun, 11 Oct 2009 16:06:09 -0600, "SteveB"
wrote:

A GPS that will count that short a distance, and calculate an area as small
as 500 square feet? I want one!

Steve

It may be pedestrian model. Best suited for city slickers. These can
help navigate short distances and home in shorter distances.

(Doug Miller) writes:
In article , bud-- wrote:
Mike Paulsen wrote:
Here's another: Measure the pH of the pool water. Add a known amount of acid,
and measure the pH again. Compute the volume of water from the difference in
pH readings.

Well the pool presumably have additives which may act as buffers so
not so easy unless you know the exact chemical composition of the pool
"water".

SteveB wrote:
How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.

Steve



Kidney shaped. Do you just *want* people to pee in the pool? (the power
of suggestion)


Bob

In article ,
blueman wrote:

Circle has area: pi * r^2

The old joke. Country yokel's son goes off to college.

Back at xmas vacation. "Well, son, what'd they teach you at college?"

"Pi r^2"

"Sure am wasting my money sending you off -- everyone with any
sense knows that pie are square!"


Has anyone NOT heard that one?


David

In article ,
David Combs wrote:
In article ,
blueman wrote:

Circle has area: pi * r^2

The old joke. Country yokel's son goes off to college.

Back at xmas vacation. "Well, son, what'd they teach you at college?"

"Pi r^2"

"Sure am wasting my money sending you off -- everyone with any
sense knows that pie are square!"
^^^^^^ round

Only I could screw that one up! :-)

David

In article ,
blueman wrote:
Metspitzer writes:

On Wed, 7 Oct 2009 13:10:18 -0600, "SteveB"
wrote:

How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.

Steve

0.45 x (A+B) x length x average depth x 7.5 = volume (in gallons) of
kidney or irregular-shaped pool
http://www.1paramount.com/poolcare/formulas.php
Google is your friend

The OP asked for AREA not volume in gallons.
Also your formula at best is some vague type of approximation since
there is no standard kidney-shape and certainly irregular-shaped is
even less well-defined. Although since the site doesn't define what A
and B are, the formula will by definition be true for some values of A
and B


Learned this once (and yes, it has a name that I don't remember):

For symmetrical even if then leaned over -- something like that,
sphere, cone, etc:

Volume = area of top + 4 * area of middle (cross section, I guess) +
area of bottom, all divided by 6.


David

In article ,
HeyBub wrote:
MikeB wrote:
On Oct 7, 3:04 pm, "HeyBub" wrote:
SteveB wrote:
How do I figure the area of a pool from the perimeter? It is a
kidney shaped (exaggerated) pool.

You can't. That's what Integral Calculus is for.

So what is the formula then, or how would one use integral calculus to
derive the area of the pool?

First you write the equation for the curve as a function of x: f(x) =
equation.

Wrong. It isn't a "function" -- for every x, there's TWO y's.

Maybe somehow bisect the top of the pool, symmetrically. Or not symettrically.

NOW you have TWO SEPARATE curves, each doable (unless it's *really* weirdly
shaped, parallel nooks and crannies(sp?)) via a y = f(x).

Integrating, you'll get two areas, to add together.



Area = the integral [from 0 to max x] f(x)dx. Turning the crank gives the
answer.
http://hyperphysics.phy-astr.gsu.edu.../integ.html#c3



An alternative is the Monte Carlo method.

Surround the curve with a box. Generate random points that will land inside
the box. Determine whether each generated point is inside the curve or
outside. If 62% of the random points lie within the curve, the area of the
curve is 62% of the area of the box. Obviously precision grows as a function
of the sheer number of points.


Long time ago, before computers, they had these mechanical complicated-linkage
based things ("planeaometer"? something like that?), at the end of which
was a tracing-needle or a pencil, etc, and when you traced around the curve,
somehow you could read the area off some dial.

Fancy stuff out there before (digital) computers.

They had tide-predictors that emulated the fourier series that
worked for that particular point (30 miles up the coast it might
be very different series).

Of course (well, maybe not "of course") the Norden bombsight was
totally (I think) mechanical, via gears, cams, linkages, etc (I guess --
I think it's still classified).


David

In article ,
Jon Danniken wrote:
SteveB wrote:
How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.

You can estimate the area by overlaying the circumference of a couple of
circles, figuring the area of each, then adding those areas together. Take
the remaining area not covered by your circles, and estimate that area,
adding it to the previous area to obtain your final rough estimate.

Jon



Circles, triangles, etc. Maybe just triangles.

That's what they've been doing since the beginning
of computer graphics, for "filling" closed curves
with colors, say.

Stupidly, I forget the generic term for computing a set
of triangles to, to some approximation, "fill" an area.

And to figure an approaching-optimum set of triangles,
ie the FEWEST number of them (differently sized, of course)
to fill an area. Triangles REALLY easy to compute, so easy
that long ago they designed chips to do it "in hardware",
REALLY quickly.

A picture might contain a jillion triangles, so doing them
fast is important. Especially if you're doing it "in real time",
ie like in an animation.

Not that I've ever done any of this stuff, nor even
taken a class in it. But I am a mamber of ACM "SigGraph",
and once a year get this heavy book of the yearly "proceedings" --
man, you have to be a physicist to do some of that stuff,
and you want to see applications of REALLY hairy math,'
and REALLY clever algorithms, you'll see them there.


Again, not that I actually understand it all, but I can at
least read *parts* of *most* (well, many) of the included
"papers". Nifty stuff indeed!

Oh, there's a newsgroup that's related: comp.graphics.algorithms,
where I sometimes ask (my usual stupid) questions.




David

In article ,
harry k wrote:

I like it. Could use a string, stretch it carefully around the pool
edge, measure length, solve for diameter of circle, solve for area.

Harry K

How about one of those pencil-like things with a wheel on the end,
and you wheel it around the perimeter (on the photo), and
read off the perimeter directly. (Plus converting some units.)


David

On Nov 1, 9:48*pm, (David Combs) wrote:
In article ,David Combs wrote:
In article ,
blueman wrote:

Circle has area: pi * r^2

The old joke. *Country yokel's son goes off to college.

Back at xmas vacation. *"Well, son, what'd they teach you at college?"

"Pi r^2"

"Sure am wasting my money sending you off -- everyone with any
sense knows that pie are square!"

* * * * * * * * * * * * * ^^^^^^ * round

Only I could screw that one up! *:-)

David

You _almost_ got it. Pi R Square...No pi are not square, cake are
square, pi are round.

Harry K

David Combs wrote:
In article ,
David Combs wrote:

In article ,
blueman wrote:


Circle has area: pi * r^2

The old joke. Country yokel's son goes off to college.

Back at xmas vacation. "Well, son, what'd they teach you at college?"

"Pi r^2"

"Sure am wasting my money sending you off -- everyone with any
sense knows that pie are square!"

^^^^^^ round

Only I could screw that one up! :-)

David




Lim time!

Said a rather dense yokel named Pete,
"Mathematics has fair got me beat.
I thought a square root,
Is some sort of fruit,
And Pi is a nice thing to eat."

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.

On Mon, 2 Nov 2009 05:48:15 +0000 (UTC), (David
Combs) wrote:

In article ,
David Combs wrote:
In article ,
blueman wrote:

Circle has area: pi * r^2

The old joke. Country yokel's son goes off to college.

Back at xmas vacation. "Well, son, what'd they teach you at college?"

"Pi r^2"

"Sure am wasting my money sending you off -- everyone with any
sense knows that pie are square!"
^^^^^^ round

Only I could screw that one up! :-)

David


Cornbread are square :-)

(David Combs) writes:
In article ,
blueman wrote:
Metspitzer writes:

On Wed, 7 Oct 2009 13:10:18 -0600, "SteveB"
wrote:

How do I figure the area of a pool from the perimeter? It is a kidney
shaped (exaggerated) pool.

Steve

0.45 x (A+B) x length x average depth x 7.5 = volume (in gallons) of
kidney or irregular-shaped pool
http://www.1paramount.com/poolcare/formulas.php
Google is your friend

The OP asked for AREA not volume in gallons.
Also your formula at best is some vague type of approximation since
there is no standard kidney-shape and certainly irregular-shaped is
even less well-defined. Although since the site doesn't define what A
and B are, the formula will by definition be true for some values of A
and B


Learned this once (and yes, it has a name that I don't remember):

For symmetrical even if then leaned over -- something like that,
sphere, cone, etc:

Volume = area of top + 4 * area of middle (cross section, I guess) +
area of bottom, all divided by 6.



Your formula is certainly in general FALSE since volume is
3-dimensional and grows to first order as the cube of some notion of
"radius" while your formula is just a weighted sum of 3
cross-sections.

Volume is volume.
Area is area.
Irregular shapes don't in general have nice formulas and require
numerical approximation/integration.