# Scratchbuilding from a picture

Discussion in 'Getting Started' started by Nomad, Oct 4, 2007.

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Hello everyone
I have a picture of a building I might try to build. Any idea how I would figure out the dimensions of the building in ho scale?

Loren
2. ### sumpter250multiscale modelbuilder

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The best way to find dimension, is to have at least one known measurement. Doors,today, are typically 80" tall.
Unless you have a lot of space, or the building is small to start with, you'll have to selectively compress, so actual dimension isn't as critical as overall proportion.
3. ### Dave R.Member

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The important thing is to have a flat view (of course, now you need two pic's one of front and one of the side) If your pic is on an angle you'll have to deal with diminishing scale, ie vanishing point, but since there are few compound curve on buildings, its doable.
As Sumpter wrote, you need a known; if a prototypical door is 80 inch's (2033 mm, working in metric much easier) divide that number by
87 (thats H0, 160? if it's "N"). That's 23.4mm. Now measure the door on your picture (you can buy a nice set of digital calipers for around \$15) divide the 23.4 by that number, you'll get a new number, let's call it 8.8, If you multiply any measurement on your FLAT picture by 8.8 it will give you H0 scale. Better yet, take it to "ginkos" and have the picture enlarged 8.8 times (that's 880%). If the pic is larger than the scale, reverse the process from "divide the 234 by that number". If the picture is at an angle, draw a strait vertical line along the door-edge (or any know prototypical measurement, like a window) in the pic that you are measuring. From the measurements you take along that line(s) you can calculate the height of the components, but the lengths will have to be estimated. It's actually a lot of fun when you get the hang of it, I plan to put my house on my layout. Maybe someone can further clarify my explanation. Sorry if it seems convoluted.
Good luck,
Dave
4. ### Dave R.Member

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Sorry, thought I should mention, if you use vertical lines drawn on an angled picture you'll need to recalculate scale for each line. You should be frugal with the lines.
Dave
5. ### ezdaysOut AZ way

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As the rest has said, you need at least one dimension to work from. I took some pictures of a chapel I wanted to build and paced off the width so I could calculate the rest. The structure was still too big for my layout at 1:160 scale, so I made a couple of paper mock-ups at different scales to get it to look right. I settled on 1:212, but used my calculations so that I got the proportions correct. I did the same with a grain elevator a while back. Once I found the height, the rest was easy to scale. I found most of the pictures and the necessary dimension on the Net. Again, I scaled that down to 1:260, otherwise it would look overpowering on my layout.

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Thanks for responding, guys. What I am wondering, does it matter what scale the picture is? Or does the picture have to be scalled? Right now the door in the picture measures about 1 5/8" tall.
I do have straight on front and side views, and I am not worried about exact dimensions. As Sumpter wrote, I will need to build it to fit my layout.

Loren
7. ### sumpter250multiscale modelbuilder

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Scale is nothing more than a reduction ratio. the door, in your photo measures 1-5/8", 0r 1.625". this represents an 80" door, so....80 divided by 1.625, = 49.23. your door is almost 1/48, or almost O scale.
Now, if you want, you can measure everything on the vertical line of the door, multiply by 49.23, and get the actual size in inches. For example, half the height of the door is .8125". multiply that by 49.23, and you get 39.999375" (40") which is half of 80".
Using an HO scale rule, you measure off the actual number of feet, and/or inches, and that is the HO scale size of the object.
If you do not have a scale rule, and have to use real inches, measure the size in the photo, and multiply by .5658708 to get the actual size in inches of the scale part. 1.625" X .5658708 = .91954", so the door would be .91954" to be an 80" door in HO scale ( WARNING! the .5658708 only applies to the one specific photo, at one specific vertical, and is the ratio of the actual inches, 80 divided by 87(ho scale),.91954, and the actual inches of the photo 1.625" (1-5/8")---.91954 divided by 1.625 = .5658707) as the actual inches of the photo decreases, the multiplier will increase eg. if the photo height measures .8125 (13/16ths), .91954 divide by .8125 = 1.1317415. anything on that vertical would have to be multiplied by the new figure of 1.1317415). HO scale is 1/87.1, 1/87 works just fine...87 X .91954 =79.99998"(back to the 80" door).

Another trick, fasten the photo to a large enough piece of paper, lay a straightedge along the base of the building, and extend the line to the vanishing point (where the lines of perspective meet), then do the same for the top of the wall, to actually set the vanishing point. A line, then drawn from the vanishing point, along the top of the door, will be an 80" height line, on any vertical that intersects it, measured from the base line.
A vertical line along the "tall" edge of the door, can be subdivided into feet and inches, determined by the height of the photo door. The height of any point on any vertical line can then be determined by selecting the desired point, laying the straightedge from that point to the vanishing point, and noting where the straightedge crosses the known vertical of the edge of the door.
Horizontal line measurement gets tricky. One of the lines of perspective that you need to draw, is one that is perpendicular to the vertical.
Let's take a window. You can measure the vertical height fairly accurately, but the horizontal measure is constantly shortening. What usually does not change is the ratio of height to width (as the width is decreasing, so also is the height, by the same amount. So, measure the width, on the line perpendicular to the vertical (you may have to extend verticals below the base line depending on the photo's perspective). Determine how many times that width, goes into the height. If the window measures .5" H on the photo, and the width on the horizontal is .25", then the window is half the width of the height or, 21-3/4" X 43-1/2".
For every horizontal measurement, you will have to draw to verticals, measure the line segment perpendicular to the verticals, and determine its ratio to the vertical, to get the actual feet and inches distance between the verticals.
Confused?? One of the magazines RMC, MR, RMJ, etc. had the mathematics used to determine measurements on perspective photos.

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9. ### Dave R.Member

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Sumpter is right you're pictures are almost 1/48, nice bit of luck.
Take the pictures to "Kinkos" (wherever, maybe you can do it on your own computer) and have your pictures reduced by 55% for "H0" or 300% for "N". Get several copies so you can cut them up and paste them to your building material. This saves a lot of measuring but be careful to keep things square. Compare your work to a manufactured scale building, see if they "seem" compatible.
You can buy manufactured scale windows and door etc.
Dave
10. ### 60103Pooh Bah

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There are a few other dimensions that you can look for. Bricks are a standard size, so you can count rows of bricks and columns of bricks to get a reasonable estimate (this can also help you check your door size). If you measured the width of the planks in the wood siding, you can estimate from that. You have to watch out for "scale" brick paper/plastic sheet as a lot of these are for some other scale (even if labelled HO).

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Thank you all for the help and advice. I have a program called IrfanView and started messing with the scale of the pictures. The door now measures 82 inches in the picture. That should be close enough to scale for me to measure the rest of the building. Thanks again.

Loren
12. ### rlundy90Member

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For the drawings I entered in the model contest I used my digital camera to take pictures of the original from different distances. I then printed them out on the poorest quality. I found one on which the door measured out at 7" on the scale rule. I used that picture to take my measurements from. That way there is no calculations to do. the drawings worked out great. Ron

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Thanks Ron, but it is a picture I found here.

Loren

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