On 06/25/2007 05:23:01 PM, bulia byak wrote:
On 6/24/07, bulia byak <buliabyak@...400...> wrote:
On 6/23/07, Tom Lechner <lechner@...1707...> wrote:
http://www.iro.umontreal.ca/~ostrom/publications/pdf/SIGGRAPH99_FacialEngrav...
Looks like my enthusiasm was premature. After reading the entire paper, I see that the most difficult part - separating the image into areas and choosing the shape and direction of engraving lines - is still done entirely manually in this approach.....
Can potrace or some such tracer be used to trace out regions that break along a certain kind of differing contrast? In the head sculpture in the paper, the face is a broad area with a gradual change of contrast, which borders things like the nose, hair and background. The borders between these things are much more abrupt changes in contrast. I wonder if there's some way to distinguish regions based on the amount of "tangle" inside (hair versus forehead, for instance)? Group according to certain threshholds of standard deviation of contrast per area?
Whenever I do lots of line work I tend to align lines along contours of darkness, or a little diagonally from it in roundish shapes like people, and perpendicular to contours for blocky areas that should really stand out. Lines on opposite sides of a border between regions might be perpendicular, which emphasizes foreground versus background. This sort of general rule could be used to help define line directions within regions.
My ideal engraving tool would be half automatic and half manual. Regions and general directions for lines could be found automatically, then these guides could then be tinkered with by the artist, who finally decides when to actually turn the guides into engraving lines. Computers can play chess pretty well, but they still don't know much about aesthetics! That Strokes Maker program, which looks kind of neat: http://www.vectools.com/en/StrokesMaker1.aspx seems to let you define a single type of path to mimic. This would at least be comparatively easy to implement: Select a path for a mask, select another path to mimic, and press the "engrave" button.
So anyway, Tom ----------- http://www.tomlechner.com http://www.laidout.org