Height-Related Sinking and Shifting of polyline

[ApodemusSylvaticus]

Hello everyone,

I'm currently developing a component that displays a visibility sector using a polyline, and I've encountered several issues that I'd like to fix:

1. Height-Related Sinking and Shifting
   When creating the polyline, we need to specify a height to prevent the line from sinking below ground level. However, it’s not entirely clear what determines this height. Furthermore, adding height causes a noticeable offset from the initial point when viewed up close (see the attached video). How can we address this so that there’s no sinking below ground and no apparent shift at close range?

2.Line Thickness Variation
Sometimes the polyline appears thinner, and this seems to depend on a variety of factors (e.g., height, sector angle, line thickness). Is there a known way to keep the line thickness consistent regardless of these parameters?

3.Visible Sector Length Change
Changing the height also alters the visible length of the sector. Is there a recommended approach to eliminate or reduce this effect(effect is subtle but still unpleasant)?

4.Approach Validity
Finally, is the current approach for solving this problem the right one, or should I consider a different solution or technique altogether?

Any insights or suggestions on how to resolve these issues would be greatly appreciated. Thank you in advance for your help!
Example repo: https://github.com/ApodemusSylvaticus/openglobus-example
https://github.com/user-attachments/assets/01ccb8e2-9d53-46d1-a1a5-37584bf1f905

[pavletto]

Hello, @ApodemusSylvaticus

1. To prevent the polyline from sinking into the ground, there is a property called clampToGround. If I remember correctly, I haven’t passed it along yet, but I’ll try to do so soon. However, sinking can still happen because it depends on how many points your polyline has. If it’s drawn very straight over a terrain, it will still go underground. Regarding the shift: that’s nothing more than perspective distortion—if you trace a ray from the point at a given height down to the ground where your billboard is located, you’ll find they coincide.

2. Concerning line thickness, it appears to be a bug in the core, and we’ll think about how to fix it. The issue is that if the line thickness exceeds the distance between the first two points on the arc (in your case), it tends to narrow. You can solve this in your specific case by increasing the arc step to, for example, one degree. Alternatively, you can split the overall polyline into several parts, so that at turns the lines won’t thin out.

3. I’m sorry, but I didn’t understand what you meant.

4. As an alternative, I can suggest using a geoobject. In our projects, we used it specifically for displaying camera view angles. If you don’t need 3D, you can follow the suggestions mentioned above.