Cyclic Artefacts if disableDepthTestDistance: 0 for billboards

CesiumJS
1

Hi,

I get cyclic artefacts if I set disableDepthTestDistance: 0 for billboards

Here is a sandcastle

image
image1228×600 99.7 KB

Tis occurs if I choose World Terrain as DTM.

Rüdiger

2

Hi @Ruediger_Brand,

thats normal, because the billboards are angled towards the camera and therefore getting partially overlayed by the terrain depending on its angle relative to the ground.

You should not define the disableDepthTestDistance as “zero”, use some positive number instead, as described in the documentation:
“Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain. When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.”

Best, Lennart

3

Hi @lennart.imberg,

I think that isn’t normal, but I don’t know if you understand me.

I draw this cyclic effects in the image

image
image1228×600 114 KB

Is this normal ?

Rüdiger

4

Hi @Ruediger_Brand,

I have drawn a little quick and dirty image to illustrate, what I meant above.
If you set disableDepthTestDistance: 0 it’s like that:

quick_and_dirty
quick_and_dirty737×413 2.1 KB

The billbords are partially under the terrain, depending on their angle towards the ground, because they all are aligned to the camera

If you set disableDepthTestDistance to a positive number, you can see them through the terrain/globe

5

Hi @lennart.imberg ,

i will try it

Thank you

6

@lennart.imberg

Hi Lennart one question:

disableDepthTestDistance : Number

Scene/Label.js 1040

Gets or sets the distance from the camera at which to disable the depth test to, for example, prevent clipping against terrain. When set to zero, the depth test is always applied. When set to Number.POSITIVE_INFINITY, the depth test is never applied.

I have set the value to 20000 - what does this mean, I thought bigger than 20000 the depth test is disabled, is this right ? I observed,that the depth test is NOT applied between 0 and 20000 distance ?

Rüdiger

7

HI @Ruediger_Brand,

sorry for the late response, I was on vacation for a while. Yes, your observation is correct. Thats why I set the distance to Number.POSITIVE_INFINITY in some cases. Be aware I did’nt dive in the related source code yet, so I can only tell you, that my obervations are the same.

Best, Lennart

8

@lennart.imberg

thank you