Does anybody know of a simple program that will take bitmap line drawings and turn them into closed shape vectors? I’d like to allow 3rd graders to design CAD files (with crap accuracy but it won’t matter) by drawing cross sections, scanning them, and lofting them together in the computer.
At worst I can write an ultra simple line of best fit program in python, but that would be slow and clunky and couldn’t handle serious concavities.
Why don’t you have them draw with vector graphics to begin with?
That’s an alternative if I can’t figure this out. TBH I’m not sure how capable with a computer 3rd graders are now.
You need Photoshop really. It is a simple process but you’ll need the right software. Here’s a tutorial vid I made that will help: http://www.youtube.com/watch?v=LN6Y3uQGCsc
@Matt_Hale that would be Illustrator which is needed, not Photoshop. Probably out of reach for a 3rd grade budget.
Does Inkscape or Gimp have a similar functionality?
Inkscape can produce and edit vector graphics, and is FOSS. Gimp doesn’t have any vector editing or export capability.
Maybe you could describe what you plan doing more in depth?
Maybe this will help? 3Dtin seems interesting http://blog.makezine.com/2013/03/28/free-alternatives-to-tinkercad/
Inkscape has it. Trace Bitmap in the path menu. and it is free. It is not near as good as illustrators, but it works
@Steve_Kelly1 What I read is have the kids draw stuff on graph paper, then vectorize a scan of that drawing so it can be extruded into a 3d shape for 3d printing.
Hi @Mike_Creuzer . To do it effectively, I find that using both Photoshop and Illustrator is the best solution for me.
You can try Vector Magic
http://vectormagic.com/home
the have a free limited online version.
Note: I only tested the payed version so i don’t know how good the free online version is.
Alright guys thanks for all the input. I’ll look into Inkscape when i get home. I’ve got CS3, but i don’t know if it will have this functionality.
Also, the plan is to have them draw multiple cross sections and use the loft function common in many CAD programs to create a 3d object from them.
It may prove to be easier to just show them 123d design, but I’m going to have a few kids try both and see which works better for them.
3rd graders? Don’t go for Illustrator or Photoshop! Have instead a look at free tools like http://www.3dtin.com or http://www.publishyourdesign.com/modeler. In July we will (probably) be using 3dtin for a modelling project with 4 graders.
Try photo2mesh, this will convert bitmaps to 3d STL files, not quite what you looking for
inkscape > trace bitmap is my advice too.
I just spoke with the teacher I’ll be working with. He actually thinks something like 123d will be easier for them to understand because they can work it out on their own with trial and error rather than trying to understand when I say “Draw cross sections of your object”
You might try asking the guys at doodle3d as they have an app that does just that.
mmm i like to add some info here, i have done some dabbling 
check out my blog – here --> http://3roomlabs.blogspot.sg/2013/03/018-more-refinements-from-kicad-to.html — and here --> http://3roomlabs.blogspot.sg/2013/03/022-further-experiments-with-magic.html
… the above were more of a finding a way to vectorize drawings, and dump them into Gcode. maybe it can give you some ideas.
Try bmp2cnc, this program converts bmp images to g-code