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I have a paper print (blue print for you old guys) that are scaled drawings of wing ribs for a home built airplane. I would like to be able to scan them so I could CNC cut the forming blocks. Most of the software I see is for terrain mapping and architectural applications. I just want to take some digital pictures of a flat print and have a scalable closed line in CAD. Photogrammetry (sp?) is new to me and I am not sure what to make of the different descriptions. Can anyone help point me in the right direction?

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2 Answers 2

1) Get a good digital scan of your original. It's important that you get good contrast: good dark lines on a good white background. If that's not possible you may be able to clean it up in the next step.

2) Import that digital scan into CorelDraw (everything here can be done in Adobe Illustrator, too, but I don't know Illustrator and, anyway, CorelDraw is cheaper).

3) Your drawing is a "bitmap" in CorelDraw. If the lines aren't very dark or there is a lot of gray in the background, use the Image Adjustment Lab to clean it up. Select the bitmap, select bitmap->Image Adjustment Lab. The trick I use most is to turn the "Highlights" slider all the way to white and the "Shadows" slider all the way to dark and then turn the "Midtones" dark. Sometimes that's too much and you want to go to light with the midtones or even just tweak it a bit so play around but usually dark midtones will do OK. Click on OK. If you don't have a very good black and white document with clear lines, try the same thing again.

4) Now that you have an image with dark lines on a white background select Bitmap->quicktrace. It will appear to do nothing but the original image is now under an object which is probably what you want. Press alt-Enter to open the object properties window.

5) Select the pen (outline) tab and then select width:hairline. THen select bucket (fill) tab and click on the x. This will take the original image and show it as an outline.

6) If this is what you want then delete the original image and save this in a format you like. SVG is a good choice but PDF will sometimes work well. Some CAM machines are actually driven from CorelDraw in which case you're in good shape.

7) If this is NOT what you want then you'll have to play with it a bit. Other options include: a) If there is too much color or gray in the art, try changing the mode to black and white (bitmap->mode->black and whit and then select "Line Art". b) If there are too many lines try ungrouping your image (ctrl-U) and then selecting some of the lines you don't want and hitting delete. Be careful not to delete too much, of course. c) If the trace is just a hot mess you can try the "Centerline trace" and "outline trace" (bitmap->centerline trace and bitmap-outline trace) forms. They have a lot of options and you'll have to just try things and see what works for your particular image.

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We're using Corel Draw at work to drive a bench laser cutter (can cut and engrave plastics, wood, aluminum, glass etching...).

Corel Draw will allow you to create a vector image from a scan. This will allow you to scale your model and export to a CNC friendly format (DWG?).

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