Various Freestyle glitches, likely due to errors in edge detection #46278

New Issue

Kalcifer Kandari · 2015-09-26T22:33:29+02:00

Kalcifer Kandari commented

2015-09-26 22:33:29 +02:00

System Information
Mac OSX Yosemite 10.10.5 (14F27)
MacBook Pro (17-inch, Mid 2010)
Processor: 2.66 GHz Intel Core i7
Memory: 8 GB 1067 MHz DDR3
Graphics: NVIDIA GeForce GT 330M 512 MB

Blender Version
Broken: 2.75a (e27589e), 2.76 (e24ea81)

Short description of error
Examples file 26 September 2015 19:25:54 3.blend, render from file

Starting from the right in the example file/image (all examples use the 'Silhouette' Freestyle edge type):

(Object name: 'Cube') Happens when faces are exactly in line with the camera perspective (maybe something to do with two freestyle edges being in front/behind each other as the camera sees them). This is very difficult to avoid in busy scenes. (Does not need subdivision surface on the objects, or an orthogonal camera as in the example file).
(Object name: 'Cube.001') Happens when a thin object has a thick freestyle line. (In the example Freestyle lines have strange protrusions at the top and bottom of the object, and the lines on the side are not straight).
(Object names: 'Cube.002', and 'Cube.003') Happens when flat faces of two objects touch where at least one has Freestyle lines. One of the faces of one of the object can be larger than the other (for example, having a cube with a Freestyle silhouette land on a plane with gravity will also reproduce this). (In the example there are missing sections to the outlines of the cubes, the lines can also be dappled).

**System Information** Mac OSX Yosemite 10.10.5 (14F27) MacBook Pro (17-inch, Mid 2010) Processor: 2.66 GHz Intel Core i7 Memory: 8 GB 1067 MHz DDR3 Graphics: NVIDIA GeForce GT 330M 512 MB **Blender Version** Broken: 2.75a (e27589e), 2.76 (e24ea81) **Short description of error** Examples file [26 September 2015 19:25:54 3.blend](https://archive.blender.org/developer/F239670/26_September_2015_19_25_54_3.blend), render from file ![untitled.png](https://archive.blender.org/developer/F239668/untitled.png) Starting from the right in the example file/image (all examples use the 'Silhouette' Freestyle edge type): - (Object name: 'Cube') Happens when faces are exactly in line with the camera perspective (maybe something to do with two freestyle edges being in front/behind each other as the camera sees them). This is very difficult to avoid in busy scenes. (Does not need subdivision surface on the objects, or an orthogonal camera as in the example file). - (Object name: 'Cube.001') Happens when a thin object has a thick freestyle line. (In the example Freestyle lines have strange protrusions at the top and bottom of the object, and the lines on the side are not straight). - (Object names: 'Cube.002', and 'Cube.003') Happens when flat faces of two objects touch where at least one has Freestyle lines. One of the faces of one of the object can be larger than the other (for example, having a cube with a Freestyle silhouette land on a plane with gravity will also reproduce this). (In the example there are missing sections to the outlines of the cubes, the lines can also be dappled).

Kalcifer Kandari commented

2015-09-26 22:33:29 +02:00

Changed status to: 'Open'

Kalcifer Kandari commented

2015-09-26 22:33:29 +02:00

Added subscriber: @KalciferKandari

Bastien Montagne commented

2015-09-27 10:56:57 +02:00

Added subscriber: @mont29

Tamito Kajiyama was assigned by Bastien Montagne

2015-09-27 10:57:20 +02:00

Anna Celarek commented

2015-11-13 19:52:28 +01:00

Added subscriber: @AnnaCelarek

Tamito Kajiyama commented

2015-11-14 02:40:36 +01:00

You have chosen the Inside thickness position option in your 'test' line style. The first two cases as to objects 'Cube' and 'Cube.001' suffer from a technical limitation of the Inside thickness option.

Specifically, the Cube object (actually a cylinder) has many parallel edges along the height of the cylinder, and they are all perpendicular to the screen (image plane). These edges are feature edges classified as silhouette edges. The Inside option is applied only to silhouette lines and border lines by the way, because being inside and outside cannot be defined for other line types (e.g., crease lines and edge marks). Now the silhouette edges that are made of the edges perpendicular to the screen plane pose an issue: there are no left and right sides that are inside as to these silhouettes. This is a special case where the inside-ness cannot be defined even for silhouette (and border) lines. For now this case is not properly handled, so that's considered a bug.

Concerning the case with Cube.001, the Inside option seems to work as expected, and that is why you have thicker ends at the top and the bottom. What is happening there is schematized below in the attached figure. The red lines are silhouettes and gray areas are thick strokes positioned inside the silhouette lines. If you have chosen the Inside thickness position by purpose then this is what you are expected to get.

It is noted that the above-documented issues can be avoided by choosing the Center thickness position.

And last but not least, the third case with the other two cubes is a known limitation of Freestyle edge detection. It is prone to line visibility errors when special cases of mesh geometry occur in the input scene, including coplanar edges with respect to a plane and two edges that coincide partly or entirely. The Freestyle edge detection scheme needs improvements so as to address these special patterns on a case-by-case basis.

You have chosen the Inside thickness position option in your 'test' line style. The first two cases as to objects 'Cube' and 'Cube.001' suffer from a technical limitation of the Inside thickness option. Specifically, the Cube object (actually a cylinder) has many parallel edges along the height of the cylinder, and they are all perpendicular to the screen (image plane). These edges are feature edges classified as silhouette edges. The Inside option is applied only to silhouette lines and border lines by the way, because being inside and outside cannot be defined for other line types (e.g., crease lines and edge marks). Now the silhouette edges that are made of the edges perpendicular to the screen plane pose an issue: there are no left and right sides that are inside as to these silhouettes. This is a special case where the inside-ness cannot be defined even for silhouette (and border) lines. For now this case is not properly handled, so that's considered a bug. Concerning the case with Cube.001, the Inside option seems to work as expected, and that is why you have thicker ends at the top and the bottom. What is happening there is schematized below in the attached figure. The red lines are silhouettes and gray areas are thick strokes positioned inside the silhouette lines. If you have chosen the Inside thickness position by purpose then this is what you are expected to get. ![silhouette_inside_thickness.png](https://archive.blender.org/developer/F254372/silhouette_inside_thickness.png) It is noted that the above-documented issues can be avoided by choosing the Center thickness position. And last but not least, the third case with the other two cubes is a known limitation of Freestyle edge detection. It is prone to line visibility errors when special cases of mesh geometry occur in the input scene, including coplanar edges with respect to a plane and two edges that coincide partly or entirely. The Freestyle edge detection scheme needs improvements so as to address these special patterns on a case-by-case basis.

Tamito Kajiyama was unassigned by Dalai Felinto

2019-12-23 16:37:26 +01:00

Dalai Felinto commented

2019-12-23 16:37:26 +01:00

Added subscriber: @kjym3

Germano Cavalcante commented

2020-01-16 02:58:48 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-01-16 02:58:48 +01:00

Changed status from 'Confirmed' to: 'Archived'

Germano Cavalcante closed this issue

2020-01-16 02:58:48 +01:00

Germano Cavalcante self-assigned this 2020-01-16 02:58:48 +01:00

Germano Cavalcante commented

2020-01-16 02:58:48 +01:00

Multi-report (different issues in a single report) are not accepted as valid reports.
To properly track issues we need them to be reported separately.
So closing.

Multi-report (different issues in a single report) are not accepted as valid reports. To properly track issues we need them to be reported separately. So closing.

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Various Freestyle glitches, likely due to errors in edge detection #46278