# Thread: The uber geek way of measuring your free-form pool volume

1. ## The uber geek way of measuring your free-form pool volume

I have a crazy pool designed in the mid seventies by someone that must have been under the influence of some of the finer methods of chemical enhancement. I was tired of not really knowing how many gallons it is.

Google Sketch-up is an excellent 3D drawing application that is fairly simple to use and has the ability to calculate the volume of most complex 3D shapes**.

Building the model requires accurate dimensions. So, using a long, straight board that is firmly affixed to the ground and runs the entire length of the pool, I marked off 1-foot intervals on this board, thus establishing a datum line as a measurement reference. At these1-foot intervals along the datum line, my lovely bride and I pulled the tape measure across the pool, taking 4 measurements to the nearest 0.25":

1) horizontal datum to near pool edge.
2) Horizontal datum to far pool edge
3) depth at 1' inside of pool at near edge
4) depth at 1' inside of pool at far edge.

So, the operation is take the 4 measurements, move over 1 foot, and take the measurements, and repeat until we have covered end-to-end the length of the pool and spa.

Then, take the measurements into sketch-up, and start building the model.

Here's the top-view:

Rotating toward the underside. You can see the various ledges and other features:

Back side. Here, you can clearly see each 1-foot measurement interval.

And finally, with all the facets created, you select all and group it as 1 entity. Then, select "Entity Info", and, voila -- your volume:

If it doesn't compute a volume, that means there is some disconnected facet -- a tear in the model. It's a bit particular, and takes practice to find these.

It's not perfect. The rounded corners in the transition from wall to floor are not modeled. But, it's a heck of a lot more accurate than the 20-30K gallons the pool inspector proffered when I asked him how big it was.

**It doesn't handle circular/spherical objects intersecting a plane.

2. ## Re: The uber geek way of measuring your free-form pool volum

Wow your pool makes me think of a chopped up trunkless version of the GOP logo

3. ## Re: The uber geek way of measuring your free-form pool volum

That is one mutant pool! Looks like the seaworld logo to me.

4. ## Re: The uber geek way of measuring your free-form pool volum

That's pretty awesome! Good thinking on the measurement method. I read of another TFP'er using Google Sketchup for this purpose, but I don't think they went to such great lengths to do so.

What's the purpose of the board, beyond serving as a an interval marker, or is that all?
I can see its other merits, so just curious as to your thoughts on its usefulness and purpose in practical application.

I'm slightly unsure as to your measuring steps though. On 1st read, I thought you were measuring parallel to and across the board. Then it dawned on me that you were measuring perpendicular to it. What I'm not positive on though is whether you measured from one side of the pool to the board, then again from the other side to the board, or if you measured all the way across? I think its the former, but there's a shadow of doubt and slight uncertainty looming.

Also, does your pool have a relatively uniform depth from edge to center across the measured points? Ie. No side slopped hopper, bowl, etc..?

Now you should see if you pass the chemical volume test detailed here: www.troublefreepool.com/a-chemical-way- ... 66473.html
That'd be awesome to see how close you are.

5. ## Re: The uber geek way of measuring your free-form pool volum

Yes, the horizontal measurements were taken perpendicular to the board. You don't really need a board, per se, but it makes a convenient place to hook the tape measure to. Yes, the bottom is quite flat -- no hopper. The radius of the wall/floor corner is generally less than 1', so, the point of measuring the depth 1' inside (or more, really) was to get to the flat bottom.

As to the shape of my mutant pool, well, like I said -- good drugs...

6. ## Re: The uber geek way of measuring your free-form pool volume

My pool was much simple, but my volume went from 18,000 to 14,000.

7. ## Re: The uber geek way of measuring your free-form pool volume

Cool. Glad to see someone else did the same trick.

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