Whatzit?

[Roy]

A photogrammetrist?

[chuck]

Bingo!

[chuck]

Usually used with a stereoscope, The most unusual part is the parallax wedge in the middle. When viewed through the stereoscope, the wedge becomes a "ladder" and you can use that ladder to measure heights.

https://www.dendrotik.com/en/product/sokkia-pocket-stereoscope/

[chuck]

[rogruth]

Chuck,
I maybe the only one that doesn't know what a Michigan Parallax Wedge is used for and how to use it.
Maybe I shouldn't worry about it but now I need to know what it is for before I forget it.

[chuck]

Roger, It's a tool used by people that have to measure things on arial photographs. The specific tools allow you to make precise measurements of area (clue 1 is a "dot grid"), elevation (clue 2 is actually the "wedge"), angles (Clue 3, a very finely divided protractor) and lengths (clue 4 is a ruler).

These are usually used in conjunction with a stereo scope to look at adjacent arial photographs in simulated 3 D.

This is a more elaborate mirror unit



This is a folding/pocket unit like we used in class or I used at work at the Corps of Engineers



When you overlay the wedge on the photo's it takes on the appearance of a set of stairs. By adjusting the stairs location to an area of interest and knowing the scale of the photo's you can get the height of objects in the picture.

This is much faster than trying to take linear measurements of objects (or their shadows) and then trying to derive the height by using trigonometry. The scale could be determined by finding something of known size (e.g. tennis court, football field, interstate highway lane width, baseball diamond, corn rows (usually 30"), railroad track (4' 8 1/2").

Here is a pdf file with a slide show summary of the basic principals:

https://www.nrem.iastate.edu/class/assets/nrem345/Week6_ALL.pdf

[webenda]

Whatzit I am holding?

[MurphOnMillerAve]

Wayne, Pistil? Stamen ?

[rogruth]

Thanks, Chuck. That does help a lot.

Wayne,
You are holding something?
Oh. Now I see it.
It looks like a baby Cobra to me.

[MurphOnMillerAve]

Chuck, section of an amusement park ride, such as a roller-coaster?

[webenda]

NO.

[MurphOnMillerAve]

:D NO.

Oh, I get it - stinger part of a scorpion's tail? (...held over a red gondola.)

[webenda]

[img]red1.jpg[/img]

Looks like the Forth Bridge.

[webenda]

You remember when I posted the scorpion riding on a flat car?
Well, this was my first attempt--getting it to stay in a gondola.

[MurphOnMillerAve]

Are they cold-to-the-touch or the same as the surrounding air ?