Grease Pencil: Better render Anti-Aliasing #85619

New Issue

Clément Foucault · 2021-02-14T01:46:17+01:00

Clément Foucault commented

2021-02-14 01:46:17 +01:00

Motivations:

Thin lines are correctly rendered using grease pencil with the currently implemented post process Anti-Aliasing. This is done by making sure the line width is not less than 1.3 and by modulating its opacity.
However, there is cases where this is not enough. For instance really dense drawings with small lines with little to no curvature still tends to flicker a lot.
Another case is when the gpencil strokes intersects the scene geometry. This makes the line less thick to the post process which makes it too small.

Proposed solution:

We propose to implement a Temporal AntiAliasing solution. It is robust and will match Cycles & EEVEE's film filtering if using the same filtering function. This only adds one temporary buffer (low VRAM usage compared to rendering at higher resolution) and is completely self contained (works with transparency and don't interfere with other features).

I propose to only implement this for final rendering since it might introduce flickering that might be annoying while drawing.

However this wouldn't solve the issue of gpencil strokes intersecting geometry.
For this I propose to erode or reproject the render's depth to match the render sample of the new AA scheme. This should fix the second problem completely.

Technical details:

Implementation just need to be ported from Workbench which has a lighter form of TAA than EEVEE. Also D10414 can be of great help to reduce render/convergence time.
Depth buffer modification can be implemented after new AA is in.

## Motivations: Thin lines are correctly rendered using grease pencil with the currently implemented post process Anti-Aliasing. This is done by making sure the line width is not less than 1.3 and by modulating its opacity. However, there is cases where this is not enough. For instance really dense drawings with small lines with little to no curvature still tends to flicker a lot. Another case is when the gpencil strokes intersects the scene geometry. This makes the line less thick to the post process which makes it too small. ## Proposed solution: We propose to implement a Temporal AntiAliasing solution. It is robust and will match Cycles & EEVEE's film filtering if using the same filtering function. This only adds one temporary buffer (low VRAM usage compared to rendering at higher resolution) and is completely self contained (works with transparency and don't interfere with other features). I propose to only implement this for final rendering since it might introduce flickering that might be annoying while drawing. However this wouldn't solve the issue of gpencil strokes intersecting geometry. For this I propose to erode or reproject the render's depth to match the render sample of the new AA scheme. This should fix the second problem completely. ## Technical details: - Implementation just need to be ported from Workbench which has a lighter form of TAA than EEVEE. Also [D10414](https://archive.blender.org/developer/D10414) can be of great help to reduce render/convergence time. - Depth buffer modification can be implemented after new AA is in.

Clément Foucault commented

2021-02-14 01:46:17 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'