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tracing building construction drawings

Jan 14, 2013 2:43 AM

i want to do some scanning of drawings of rubble masonry wall in section export it as a dwg file in autocad, and then work and modify in autocad .



However when i use the live trace command, the trace is wrongly done. for example there is a straight line having thickness 2 mm.


, illustrator traces it as a rectangle having a width 2 mm. what should i do so that a closed circle sketched on a paper scanned into illustrator is traced as a single circle by recognizing the centre of the sketched path rather than 2 concentric circles placed apart at a distance equal to the thickness of my real life graphite pencil .?

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    Jan 14, 2013 3:15 AM   in reply to arjun2

    as far as i know, you can't. what you described is the way live trace works. it has no way of distinguishing whether you want to end up with a single 'line' or a thin 'shape'

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    Jan 14, 2013 5:23 AM   in reply to arjun2

    In the LiveTrace Options dialog, turn on Strokes, turn off Fills, and set tolerances appropriately for your original.



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    Jan 14, 2013 6:10 AM   in reply to JETalmage

    wow, i've somehow managed to miss that all this time.

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    Jan 17, 2013 5:46 AM   in reply to arjun2

    You really should not even be resorting to autotracing for that image. It can be drawn properly in less time than it took to post the question; far less time than required to answer it correctly;  far, far less than the time wasted fiddling with autotrace settings for so simple an image.


    Autotracing is not a panacea, and certainly not a miracle. You don't get something for nothing.  'Garbage in / garbage out' very much applies. Illustrator's autotracing in particular includes no shape-recognition intelligence. It doesn't recognize what you intend to be "a corner" or "a circle" as such. Your result is too noisy because that image contains entirely too much noise. The autotrace routine is reading all that noise and trying to draw paths around (or through) it. That's all it does.


    An age-old common routine for reducing the noise in an image that is appropriate  for resorting to autotracing (which, again, yours isn't) is:


    1. Open the image in an image editing program.
    2. Blur it to reduce noise.
    3. Adjust curves or levels to maximize contrast and "re-harden up" edges.
    4. Save it.
    5. Autotrace it.


    The inherent trade-off is that the process of reducing noise also reduces detail, because neither a raster imaging program nor an autotrace routine really knows the difference. Basically, those "pre-processing" steps are what some of the settings in Illustrator's autotrace options dialog (blur, threshold) try to do--albeit comparitively crudely and with no direct visual feedback. You can futz around with the autotrace settings and still never get anything as clean as you need.


    Autotracing is grossly overused by those who really don't understand what vector-based drawing is all about, and/or are just too reluctant to buckle down and learn to use the drawing tools correctly. It should be used only as a last resort for the infrequent situations in which proper drawing method is impractical. Otherwise, it's just a gimmic; a cheap amateurish novelty; a kid's toy.


    If you're thinking "Yeah, but my architectural rendering is going to be much more complex than that! It's gonna have whole walls of hand-sketched stones, not just a single column!", then you need to be looking at properly drawn pattern fills, not autotracing.


    If you're thinking "Yeah, but I want to retain the hand-drawn stylistic appeal!", then you need to ask yourself why you feel it necessary for it to be vector-based in the first place.



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    Mar 21, 2013 10:32 PM   in reply to JETalmage


    Then again, there are ways to at least begin by tracing. The image took seconds to clean up (PhotoLine). Centerline trace in Vextractor (which can be vexing to use at times).


    Just playing devil's advocate, JET. However, I do agree that I would usually just go click click click.



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