Monday, September 23, 2019

Estimating Dimensions from Photos

I've had several requests to post the slides on estimating prototype dimensions on the blog. 
The following images are the slides from the presentation - I hope they are helpful:


Jack Dziadul said...

Thank you for posting the slides. I have heard that some software allows you to turn an angled photograph so that you can achieve a straight-on view of a wall. GIMP and Photoshop are options that I need to explore. The Sanborn map would be easier if available for the building in question.
Jack Dziadul
Sanford, NC

CVSNE said...

I didn't do slides on dealing with angled items in photos - the best solution is to start with a flat straight on view of course. Sometimes that isn't possible. The black and white image of the blacksmith shop is an example of this.

I didn't cover this in a slide, but did "audio" it during the clinic. (I'll defer to those who were at the clinic to judge how well I did explaining all this!)
I will often use Photoshop to straighten an image - usually I'm doing it to get a sign to place on the model, but you can do it with the entire building. Depending on the size of the building, and how far back the wall goes, the accuracy can vary quite a bit. In the case of the blacksmith shop you can get pretty close. If you have a large factory building, the results won't be as accurate.
The "poor man's" way to figure out the dimensions of something in the background or with a severe perspective is to count boards (or bricks). Again, using the blacksmith shop as an example, the clapboards measured out to 4" or so exposed - meaning 3 of them would equal 1 foot. Knowing that, it's a simple matter to zoom in on the image and count the number of clapboards at the back corner of the building.
There's better ways to get accurate measurements of a 3/4 view of a locomotive or freight car of course, but for a building this method is simple, straightforward, and produces workable measurements you can use to proceed to the mockup stage.
Hope this helps,