3 Manageable Methods Used to Scale Photos

Online_Opener_2Photos are one of the most useful methods to select projects to build. You can find almost any project in books or online where a photo is all that you have to work with. In order to develop a plan, or simply get the size of a single component, you need to be able to work from an image. But that image is never the correct size. What do you do?

We recommend any of three techniques to get the somewhat correct dimensions of a piece of furniture – there’s always room for slight modifications – for a project build. (There are, of course, others methods available, but these are the three most often used around the 360 Woodworking shop.) One involves good old-fashion ratios, while the others use a 3-D drawing tool known as SketchUp Make (the free version). Of the two tech methods, one is straight up easy and the second is more detail oriented, and probably a bit more accurate.

Old School

Let’s begin by rolling back the clock to our high school, or junior high days. Unless you were a math major, you probably sat in class wondering what in the hell you would ever use ratios for in this lifetime – maybe you still think that today. The answer, by the way, is for sizing parts.

Ratios tell us the relationship of one thing when compared to another thing. If I have three baseballs and two are signed, then the relationship of signed balls to balls is 2/3. I find it easier to work with ratios as fractions.

(Fig. 1) A straight-on view such as with this Shaker blanket chest is perfect when scaling photographs.

Before we jump too far ahead, we have to have something with which to work – we need a photo. I’ll use a photo of a Shaker blanket chest I pulled from an auction site online. Plus, it’s always better to have the overall dimensions of the project you’re planning to build if you want to copy it exactly. (If you’re looking to build the piece to fit in a specific spot, then you can establish one of the critical measurements of length, width or depth.) (Fig. 1)

The information I gathered with the photo tells me that the overall width of this piece equals 42”, the height is 32” and it’s 20-1/2” deep. What I need to determine are the remaining parts such as drawer height, divider thickness and the size of the chest’s base. (Fig. 2)

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3 thoughts on “3 Manageable Methods Used to Scale Photos

  1. Thanks for the useful info. My computer can’t run the newest version of SketchUp so I’ll be going old school ( and I think calling it “Junior high” may be very old School ).
    For those that don’t want to convert to decimal. I have A calculator on my iPad called Fraction Plus- also available for the Android. It lets you input fractions directly. The results are also given as a decimal.

  2. Glenn;

    Thanks for this quick Sketchup tutorial it was very helpful. Some follow up reading (study) on scaling from a photograph may be found in Jeffrey Green’s book “American Furniture of the 18th Century”

    1. David,

      I think that Jeffrey P.Greene’s book is one of the best out there on period furniture. I have a copy that I use for shop purposes, a copy for reading at home and I have a signed copy that I picked up when I met him in person. Great book.

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