Dashed ground primitive polylines

1. A concise
explanation of the problem you’re experiencing.

We are using
GroundPolylinePrimitives and scene.groundPrimitves to render underground
utility lines on the surface. Works
great however when we view lines horizontally from the side we see dashed

2. A minimal code
example. If you’ve found a bug, this helps us reproduce and repair it.

var undergroundPolyline = new Cesium.GeometryInstance({
geometry: new Cesium.GroundPolylineGeometry({
positions: underground,
width: 3.0
attributes: {
color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.LIGHTBLUE)
}); undergroundGeometry.add(new Cesium.GroundPolylinePrimitive({
geometryInstances: undergroundPolyline,
appearance: new Cesium.PolylineColorAppearance()

3. Context. Why do you
need to do this? We might know a better way to accomplish your goal.

We were displaying
underground utilities lines a few feet off the surface but would get tunneling occasionally
on hilly areas. The groundPrimitives
work great to solve this issue. Plus
they just look better.

4. The Cesium version
you’re using, your operating system and browser.

Cesium 1.48, which we
use within mainly Chrome on MAC High Sierra 10.13.6

Looks like this is actually an open problem in polyline rendering. I found this paper that Cesium maintainers published about it:


I don’t think it’s been implemented in CesiumJS. In the mean time, a quick fix is just making the line thick enough to avoid those artifacts at most views.

Thanks Omar, making it thicker helps some, although the behavior is still very noticeable.