David would you please send me a copy of your program,thanks Brock Beckstedt of Norfolk,Va e-mail ([email protected])

Brock -

I'll send it. This link should work as well.

http://spreadsheets.google.com/ccc?key=pTsmT0ICovja1M2IWABmVEA&gmrcpt

thanks for your reply if you are ever up here in hampton roads look me up 10=4 over and out,Brock

Brock -

Have you tried the tool? Did it work OK for you?

Dave

Hi,

Can you send me a copy of the tool.

[email protected]

Thanks

Pete -

A copy is on the way via email.

Semper Fi,
Dave

Hi there.
That tool seems very useful.
Please, would you send me a copy to

[email protected]

Thanks for your kind answer.
Cheers.
Pablo

Pablo -

The file is in the way now via email.

Semper Fi,
Dave

Intriguing. I've never seen this thread before but your program sounds interesting. As for the question posed above, well, if you don't mind thoughts of a guy who uses wooden mallets and pliers as the tools to "fix" the tools of his trade, namely weapons, here goes...

Let's take your photo as an example. We'll just do the cab since it is not quite in line with the trailer. It could just as easily be a building.

Draw lines across known parallel lines using whichever program you wish. Extend them to a vanishing point. (off screen for this purpose, but it's there)



Now draw diagonals connecting the corners. This gives you the exact center. If you know the measurement from the front to the rear, you now know where the halfway point is, and obviously its measurement.



Now do the same thing again...



This gives you yet another known reference point. You can do this for the front half, and between any two new points you generate. Now here's the kicker: You don't need that many.

You now have a set of known measurements -- the original one which is the lenght of the cab, and those you generated. Let's call those your "X" values.

Now enlarge the photo as much as you can on your screen. The larger you can get it, the more precise you can be. Measure the actual distance on the screen from your first line (representing the front of the truck) to all of your other known points. Use milimeters, inches, whatever. I have a useful metal ruler divided into tenths of an inch. Assign each of these measurements a "Y" value. Make sure each one corresponds to an "X."

Now create an X-Y Co-ordinate plane (remember arguing with your dad that you'd never need this crap because all you needed to know was how to pull a trigger, catch a ball, turn a wrench, whatever...?) on your computer.

Now, the X axis will be in whatever unit of measure you measured the truck with. The Y axis will be whatever you chose -- it does not matter. Graph your X and Y values. It will NOT be linear, but probably look like a half parabola.

How does this help you? All you've done is create a graph!

Okay, choose an item on the truck, building, whatever the case is. Measure it ON YOUR SCREEN. Go to your graph, plot that value, and you'll have your corresponding actual measurement.

There are guys a lot smarter than I who can probably turn this into a program of some sort, but there you go.

Rob -

Outstanding!!! That is the kind of conceptual lead I have been looking for! Thank you.

I have been seriously contemplating going back to high school trig classes at my advanced age........it looks like I may be spared that pleasure!

With your permission, I'll try to work your concept into the Excel tool. It may take a while.....my real boss has me repainting a bedroom at this time.

Semper Fi,
Dave

You have my permission.

Jus' tryin' to hook a brother up. (or cousin, as they case may be for a Marine)

We Marines have always known that we were Uncle Sam's illegitimate offspring

Thanks again for saving me from having to choose between re-learning trig or poking myself in the eye with a sharp stick.

Dave

For anyone else reading, I just want to add that you can turn the whole process ninety degrees, using the top of the cab as a reference line, and known height. Then you can calculate the height of any features on the cab as well.