Model Forum / General / Railroads / January 2005

Scott,
   When building from a picture find something that you can fairly well
determine the height and width of like a door, window, laps on siding,
bricks or something next to the building. From that you can estimate
everything else. Draw your structure with basic details like windows and
doors on some card stock or heavy paper. Cut it out to make a mock up and
see if it looks right. If it looks right then its about as close to accurate
as you can get without actual dimensions.  Bruce

You can use the standard artist's perspective alignment system.

1. find the horizon in the photograph. (preferably on an enlarged photocopy :^)
Draw this line in.
2. hopefully your subject will have recognisable vertical and horizontal lines.
Check that the vertical lines are vertical to the page and at right angles to
the horizon line.
If the verticals are not at right angles to the horizon then you have a double
correction to make to the scale drawing.
3. Extend the identifiable horizontal lines out to the horizon line. For a
rectangular building or piece of rolling stock these lines should intersect the
horizon at two points, one to the left and one to the right of the center. If
not, then you've almost certainly done or got something wrong.
4. Now pick something that you know the size of. (eg a door)
Measure the picture dimension - you now have a ratio prototype/photo. You can
measure up the line of the door to calculate the height of the wall. (provided
the vertical lines are parallel)
5. Finding a length that recedes towards the horizon is more difficult.
An entirely rectangular wall is about the only way to calculate this, but if it
doesn't exist, you can construct one on your paper through those extended lines.
You will know the front corner height, the door and wall height (near the
middle), and the rear corner height. These may well be your perspective
construction lines rather than the object itself.
6. If your maths isn't university geometry level then you can divide the length
of the wall into rectangles in proportion to the height. (the ratio of height to
length has to remain constant for straight lines :-)

If a photograph of (say) a tall building is taken from street foot path level,
the vertical lines will  converge towards the top. Then you have a more complex
mathematical problem!

Regards,
Greg.P.

Out of curiousity, can you post a photo? I want to build a scratchbuild
a yard tower too -- something similar to the one in Bakersfield, CA,
shown on page 9 of Trackside Scenes You Can Model.

Cheers,

Colin

Depending on how tall the structure is, I saw this web site where a
person was doing just what you want to do.

He fabricated a 40 foot long pole that was collapsible.
When fully extended, he painted marks at 1 foot intervals on this pole.
He then had a friend stand next to the full size structure that he
wanted to model.  The guy stood with the pole alongside the building and
was photographed.  The result was a series of photographs of the
building with the graduated pole next to it.
He then used these photos to accurately build his model to perfect
scale.  He know exactly how many feet long or tall each surface was that
he wanted to build.

I'm sure the site is still around but I don't have time to look for it.

Google is your friend.

What I do when I'm working from photos is import the photo into Visio.  I
set the scale of the page to 1:87 (or whatever scale is appropriate to fit
on a page).  Then I resize the photo on the page until some known dimensions
(like doors) are the right size.  Then I place the photo on it's own layer
in the drawing and lock that layer, and "trace" the photo, drawing it to
make my plans on another layer.

Some of these drawings were done from photos as described above:

http://www.modelrailroadingmag.com/html/TracksidPenn2.htm

jeff