1. Still the smoothed corners(Should do something in tracing)
2. Swirling(Use salient directions or explicitly point out the situation?)
3. The choice of stopping points for a line; The long strokes are not always the best choice(see the Lena result). Small stokes prefers in some detailed regions or textures. Long strokes are good for the silhouettes of an object.
Two different hysteresis for threshold did control the length. Are there any easy or automatic way to choose the best parameters for different cases. By the way, this idea is used by Kang's paper.
(Should summary some rules based on perceptions or drawing techniques.)
4. How to get crossed lines?(Should have a better representation for vector field? )
5. Not good for keeping small details.Cannot show gentle structures.
Some problems might be addressed by using a particle tracing method instead of streamline tracing. What I mean is that you have a moving particle in he vector field, and at each timestep it experiences a force according to the present vector field (direction+magnitude). It also slows down (friction). If it has a high mass, it will not be affected by the vector field very much. If it has a mass close to zero, it will follow the vector field exactly (current case). We can get different styles by changing mass locally, adding more forces, this sort of thing.
ReplyDeleteThis won't help with small details, but a manual salience map may be needed for the general case anyway.
Particles can cross. If you want a hatching effect, decide when you release a particle whether it should follow the vector field or travel perpendicular to the vector field. (This works in the case of streamlines too.) But even with regular vector field, with massy particles their paths will cross.
It is extremely hard to read the blue text. Try to avoid using color for emphasis.