Hatching styles for popuped models

Randomly directions

The hatching direction is based on the ETF and the density is based on the shaded image.

Stippling styles for popuped models

Experiences: It seems the spiral mask can do more precise control over the density in the space, but slower. The direction of the spiral mask has not much influence on the effects.
Randomly control the direction of the spiral mask.

Clockwise direction

Anti-clockwise direction

The rendered popuped model is merged from the original image and the lighted model by multiplication.

The popuped model after smoothing and doing process to the hair

(a)

(b)
The order of placement is based on the intensity of the rendered popuped model. The space of each stipple is based on the intensity.(a) and (b) have different lighting conditions.

NPR effects for popuped models

Heightening(line style)

Ugly lines from the ETF and the gradients

Based on the ETF
Based on gradients

The first heightening effects based on pixels not lines

Experiences: Whitening for the highlights is only enhancement for effects. The key information still depends on the good shading.

Some watercolor-like effects when creating heightening

Choose different diffusion for different areas

The next step is to control the initial condition and the boundary condition and to use different functions or different diffusion to model the surface.

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How to deal with narrow areas?

The original image
3000 iterations, 120 seconds
2000 iterations
After 500 iterations(32 seconds), pixels with height values between 0.1 to 0.000001 are shown in red. It means the narrow areas around the hair have a lot almost-zero heights.
500 iterations
100 iterations

A better result

Not good for small regions.

Heightening with white lines on brown paper

The original image

Darker pixels are from ETF and white lines are drawn manually to show the effects. It seems the quality of white lines play an important role to show the constrast.

(Heightening: the term used for highlights applied to a drawing with white chalk or white/tinted bodycolour.)

Better long streamline

One way to make the short streamline longer

When tracing the ETF, if it stops at some pixel and let it find which pixel is valid as replacement. It gets some jagged long streamline. After poping it up by dilation, it has kind of smoothing. But it is still messy!