# Thread: finding area of something

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1. ## finding area of something

ok i couldnt think of where else to go so can some one here help me find the area of this white area in the picture. or on any odd shape like this with no set number of sides
http://www.angelfire.com/nd2/kylekon...18FM64test.jpg

2. Do you know spline theory?!?

Theorectically, the only way of figuring that out is through an approximation. Break it up into smaller pieces that you can easily find the area of (like squares, triangles, or other polygons) and get them as close as possible to the actual shape. With that picture you supplied, it's not going to be easy.

However, this might be worth a try:
Is this is a physical object you have access to? If there's some depth to it, and it's a consistant shape (same cross section all the way down) you could try filling it will liquid. Measure the amount of liquid to fill it, divide by the length and the result should be the area. Just have to watch out for units and conversertions...

g/l

3. actaully, i guess it is a physical object but it is a terminal that has had a picture take of the cross section. the camera that took the picture is a special camera and magnifies the object that is in the picture is about this size.

this is in Inches jst so you know
Height .038"
Width .058"

and i have to write a vb program that will find the area of alot of these cross sections. it must be possible cause they have found a program that they could buy that would do this but they dont want to fork out \$50,000 . the area doesnt have to be perfect the only reason they want the area is so they can see if the wires lost 25% of of the area they had before be terminated. so i was hoping there would be a good way i could do this will calculation that VB could handle.

i will look into that spline theory and see if i can use that thanks copper.

edit: i believe that photo is magnified 46 times. but not exactly sure.

4. \$spacer_open \$spacer_close
5. Ahh, the actual difficulty in your problem rears it's ugly head.

/methinks this may be beyond what a VB program can handle. I'd guess that you'd need the computing power of Maple(my personal fav - Yeah Canada!) or Matlab. BTW, you're still looking at a few thousand bucks for these programs...

And in case I haven't already crushed your spirits, here's a taste of what spline theory is about:
Cubic Spline Interpolation

This approach will approximate your curve with a spline function, from which some high-powered math can solve for such things as area.

Maybe something simpler in VB will give a close enough approximation.

Let us know how you get on with it!

6. well that kind of sucks. im sure there has be to a way to find the area. i will let you know what i come up with. thank copper

7. n/p - just wish I had a better answer for you.

If I think of anything else, I'll let you know...

8. davidoff to the rescue!

I've done quite a bit of work in image analysis and so on and know of just the solution you're looking for. If you can get some way to calibrate the image (e.g. get the guy taking the picture to include a ruler in the shot), then you can use a program called tnimage to determine the area you're searching for. It takes a bit of learning, but I've used it in doing things like laser beam profiling, analysis of diffraction patterns, etc. Check out the following link:

http://entropy.brni-jhu.org/tnimage.html

Again, this is a complicated bit of software, so think before you decide to commit to using it.

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