Tracing

[John T]

Hi Art,
This may be totally off the mark for things that you do and I only bring it up because of your celtic knot.  So if I'm out of line just ignore me.

I can produce line drawings, or scan them from hundreds of sources but when I try to get a scalable (dxf) from them I run into trouble, (the tracing piece of Aspire gives two lines for each line of the drawing).  What I want to do is a "centreline" tracing of the drawing so that I can import it into something like Aspire or Vectric and manipulate the drawing from there.  My internet searches suggest Corel Draw which I don't have or Inkscape which I also don't have and isn't available for Mac.  Anyway is a "centreline" trace program that difficult?  It seems to me in my ignorance that it ought to be simple compared with what you did for the celtic knot - I still can't get over that one!

John

[ArtF]

John:

  Yes, thats a typical question. Tracing is  a very difficult thing so most
programs do it differently. The reason the knots button is slightly to the right on
its bar is because theres a hidden button you cant press for image tracing. Im still
working on my own implementation of that. I wont release it till Im happy with it ( which
could be never. :-)  ), but I understand what your looking for.
  Problem with tracing is its very heuristic in nature, so every programmed trys to add
a bit of intelligence to it, which rarely works for everyone. We'll see how I make
out over time. :)

Art

[bosr]

Most of the tracing algorithms seem to use a series of very small lines which leave a nightmarishly difficult to cleanup jaggedy outline.

OR you end up with an extreme loss of detail.

By adding the ability to select a portion of the generated outline and having options to smooth(average), interpolate or whatever so that the selection is smoothed(jaggies removed)... THAT would make the results infinitely easier to work with.

Hope this makes sense.

Randy

[ArtF]

Randy:

  The problem has always been that as you please one person who requires tracing, you piss off another. The lines you consider important, another user wants gone. The problem is one of of being too human in nature, photos to scan come in too many flavours..make sit very difficult. There are
a LOT of theories on how best to do it.

Art

[bosr]

Hence the different flavors of edge detection.

What I'm saying is to allow the user the ability to manipulate the result of the tracing routine after the fact.  This is where they all fall short.

Randy

[Mooselake]

John:  There is an Inkscape Mac installer here, along with directions to install something called Quartz.  Been a long time since I've done anything with a Mac, and the only one I have is in pieces, so I can't try it myself.  Inkscape mac got over a million google hits, so somebody must use it.  I've used Inkscape on both Linux and Windows, although not well in either environment.

Inkscape is a big complex editor, and the tracing routine has a number of options, there's probably something in there that'll let you do what.  Finding it amongst all the drop shadows and vector shading might be a challenge.

There's a quick bitmap tracing tutorial here, although it's pretty light.  A bit of googling should find some more info it it looks worth your time.  There's a big Inkscape user community and lots of online help and tutorials - some of them even useful.

Kirk

[John T]

Thanks Kirk
I had tried the inkscape route in the past but was less than excited about it - time has past and maybe I should try again.

John