Photogrammetry

[SteveO]

My first post here, so Hi. I have tried another method which i do trust and can certainly help to get as close as possible to the dimensions needed or at the very least put you in the right direction. If you have a basic dimension such as axle distance then you can do the following. first blow up the image to A4 size, then draw a line from the top left corner of the locomotive to the bottom right corner, then the bottom left corner to the top right, where the lines cross is the centre of the locomotive. from the centre draw a vertical line straight up, this forms a new box and so do the same process over again, in the end you end up with multiple boxes getting smaller and smaller. Now take the axle distance dimension and relate that to the the vertical lines of the boxes, that will give you the dimension of each box, from there you can calculate the positions of all, IE cab length etc, easier done than said.

I think I understand but can you post an example picture please? I'm stuck on the drawing the boxes bit as they'll all be the same size and not drawn with perspective.

 

[Renovater]

Post the photo you're trying to measure on here with any known dimensions so that i can get a better idea of what it's about.

 

[SteveO]

I don't have anything in particular in mind, just curiosity as to how this method works. When I get time I'll demonstrate how I do it in Adobe Illustrator.

 

[SteveO]

Interesting article on a couple levels:
http://www.bbc.co.uk/news/science-environment-26851336

 

[Bill Bedford]

But I'm thinking of trying to use it to sort out the dimensions of the Caledonian 498 Class locomotive which I'm starting to build. There is no official GA drawing available from any of the drawing archives, but there is a good range of pictures available.

The NRM has the following drawings:

7413 Full side elevation of 0-6-0 side tank engine '527' Class C.R
12938 G.A. of 0-6-0 tank engine 4' wheel '527' Class C.R. 1921