Est. 1998 — 27 years of woodworking knowledge
Software Advice Needed
Bill Tindall, E.TN
>I took a photo to an engineer and he loaded it into a CAD program ($$$$) along with the height of the piece and in minutes he produced dimensions of all the critical parts as well as a 1:1 scale print of the curved apron and foot.
Is there something I can buy for less than $$$$ that will do these tasks?
Paper and a #2 pencil
Stephen Shepherd in the State of Deseret
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been there, done that
Bill Tindall, E.TN
>I found printing a 1:1 molding profile from a photograph with a few key strokes a better use of my shop time.
20th Century
Warren in Lancaster, Pa
>I can see the value of discovering major dimensions from a photograph. I think that if you use software to give you a molding profile you will get a nice late 20th century feel to the piece.
Re: Software Advice Needed
paul womack
>If the photo is "face on" this is quite easy; you just use known information to scale the whole diagram.
If the item is curved, so the photo is from an angle, the maths starts to get interesting.
The whole topic is called "photogrammetry"
BugBear
Re: Software Advice Needed
Bob Lang
>Hi Bill,
Nearly any CAD program will let you do this. The procedure is to import the photo, and then scale it to a known dimension. As was mentioned, the closer you are in the photo to a straight on view the better, but a point of view from the camera that is close to what you would see in an isometric drawing also works.
I would recommend Google SketchUp because it's free, relatively easy to learn and pretty useful. There is a function in SketchUp that will let you build a virtual model of a photo, but I think that's probably more than you want to do. There are also several free 2D CAD programs that ought to serve your needs just as well.
The way I go about it is to tackle finding the dimensions one axis at a time. Usually I know overall dimensions, so I will start by scaling the photo to the known height. Then I look for a point in the photo with the most intersections and establish what I call a measuring line. Because of the perspective in the photo the scale will be different on the measuring line than at other points.
After establishing the vertical measurements I work on width and depth. Again, there are a few tricks for dealing with the perspective issues. Take the top overhang on a chest of drawers for example. You know in real life that it will be equal on both sides, but it won't be the same when you measure off the photo. In this case, averaging the parts will get you pretty close. If you know the overall length of the top for example, you can measure the two legs and get an average size for each leg.
The more you know about furniture and likely sizes the better off you'll be. You can follow this same process manually directly from the photo with a set of dividers and a steel rule. You need to figure out a scale for each axis (photo size/real life size). That ratio will then tell you what you need to know. Since this is the hand tool forum, there is a slide rule like device called a proportional scale that will help you here, otherwise a calculator will be a big help. I use one that will calculate in fractions.
Hope this helps,
Bob Lang
equivalence to tracing
Bill Tindall, E.TN
>If the photo is done right (see Bob's explanation) the sizing to 1:1 with the aid of the computer software will be equivalent to tracing the actual piece. While many museums will allow a photograph to be taken, it is unlikely that a tracing can be made.
The person that did the scaling for me this weekend is Fred Stanley, 2006 SAPFM Cartouch winner for excellence in reproduction furniture. I would like to be able to do what he did, but be able to use affordable software. Fred did not seem at all bothered that this software enabled him to spend more time making stuff and less time at the drawing board.
Re: And a ruler *grin*
Marv
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Re: equivalence to tracing
Warren in Lancaster, Pa
>I am not eager to comment on Fred's work as I have only seen photographs. However I think that molding shapes made from photographs or drawings or tracings must be tempered by a feel for style and a familiarity with the original work. I also think that drawing them out helps with this process.
I have worked on projects where a fine drawing of moldings was made by an architect familiar with the historic style. The drawings were scanned and the molding cutters were made by the computer. The drawing looked good, but the resulting moldings looked like 20th Century stuff. The differences were subtle, hard to quantify. Perhaps the software is too eager to interpret every curve as an arc of a circle.
Not so easy, as I feared
Bill Tindall, E.TN
>I searched some inexpensive CAD software and reached a conclusion on a product that seemed most suited. Before purchase I asked if it would do the tasks I outlined. I received a reply that it would not import pictures. I have learned to be wary of software. In many cases what it should do doesn't meet what it can do or can do easily.
It seems to me there is a great market opportunity here.
Re: Not so easy, as I feared
Pam Niedermayer - Austin, TX
>To consumer affordable software, a photo is nothing but piles of pixels. Oh, it can do some edge detection without too much trouble, fix up edges (Photoshop), etc.; but it's unlikely to recognize forms such as furniture as such all on its own. At a minimum you'd have to trace the outlines. Having spent many hours with Photoshop tracing shapes, this is a joyless activity.
I strongly recommend you get a software ruler and measure and extrapolate 'til the cows come home.
Pam