Stippling from FS and Ostromoukhov's methods

FS:

OS:

Grid-based method to fix up the mosaic

1. Find the particle trails for each grid we specify. 

2. Store the particles.

3. After the process, deal with the stored particles and build a network.

Similar result from the dense lines as previous blog, but the coarse one is still not good. But this one may refuse very long strange line, which is what we try to do. But if we take a closer look at it, there are some artifacts from the grid.

A video for halftoning

It turns out the effects is not good for halftoning video due to no coherence between frames. It's like a noise video and cannot see the advantage of our method.

Drawing from particle trails

A simple particle system is used to follow the field.It's good for fork-like corner. But it still is a question for stopping and the setup for mass needs for testing. Maximum length is high. All are based on smooth field.

Maximum is low.

Maximum length is low.

Maximum length  is high.

Triangulation

Triangulation based on those found tracing lines.

My aim is to find a segmentation based on those tracing lines.Also I am trying to find critical points based on Greene's bisection method. But right now it seems not working.

Modified fields

Problems for which directions should be picked?

Some testing

Maximum length = 20, Density control after finding a line by refusing putting a seed in the neighbourhood

Bigger images

Without length control

Bilateral smoothing by the directional differences

Manage the order

Only showing the first level and the third level.
This image is obtained by first choose edges as first level. At the first level, only control the density. The next level is dark area, which is not well-represented now. The last level is the light area.

Put white dots on black background when it is an uniform dark area

around 40000 black dots and around 36000 white dots

This demo uses over 54000 black dots(saving 20000 dots) and around 3000 white dots.
Put white dots on chosen uniform dark area. It did work better for showing dark area. But the library for showing vector graphics I chosen only supports changing the whole background color not partially. So there might be a problem for showing vector graphics.

The white uniform area shows where the modified area is.

First try for displaying patterns(maybe useless maybe not)

#define DEF_MAXIMUM_COST_SPREAD 6000

#define DEF_MINIMUM_LENGTH_DENTRITE 0

#define DEF_WEIGHT_GRADIENT 20

Not well-defined for shapes and well-defined for sizes

It is possible to show patterns, but the quality of the patterns is questionable. And did not see many advantages over the texture-mapping way. But still interesting for me.

Digital facial engraving

http://www.iro.umontreal.ca/~ostrom/publications/abstracts.html
Victor Ostromoukhov. Digital Facial Engraving, In Proceedings of SIGGRAPH'99, in Computer Graphics Proceedings, Annual Conference Series, pp. 417-424, 1999.

Gouraud shading lines