Point Path Overlap Troubles

CesiumJS
1

Hello,

I’m currently working on creating a constellation of satellites that

display both their ground track and their orbital path.

Something that’s been causing me trouble is how it chooses to overlap these lines sometimes. When I’m in 3D mode (seeing the whole globe), there’s no trouble. The orbital path is in LEO, so naturally, the line is on top of the one shown along the Earth’s surface. However, when I switch to 2D, it seems to reformat the z-axis, if you will. I see the ground track line takes priority as it appears above the orbit line. Normally, this wouldn’t be so troublesome since they’re technically the same line, but since my orbit track updates in an inertial frame, it will shift and be covered up, which is frustrating.

Both the ground track (blue) and orbital path (red) are path elements that follow a point. The images show what I’m confused about a bit better.

cesium
cesium2862×1324 498 KB

Hopefully, there’s an easy fix or some type of knowledge on how 2D mode reformats things that can help.

Thank you.

2

Hi Caleb_Arbreton,

Welcome to the Cesium community. We are excited to see you building with our products.

Are you using CesiumJS to create this or another viewer? If it is CesiumJS, are you able to provide a Cesium Sandcastle that illustrates the issue? That will help the community better assist you and provide recommendations.

3

Hi Mark,

I’m not sure how to implement the sandcastle but I can take a look at it. Is there a learning resource for building one out there?

Thanks

4

Okay, I believe this should work. Normally I make a large .json file in the .czml format to interface with the .html front end. I was able to paste one of the .jsons in and I can see the situation.
Link to Sandcastle

Hopefully that helps,

Thanks

5

Thanks for providing that Sandcastle. I took a look at it and didn’t see the blue gray line that was in your images. Should that be visible in your Sandcastle?

Since you are using Cesium JS and this question is focused on dispalying data and Cesium JS and not loading data from Cesium ion, I’m going to move this topic to the Cesium JS group. That will help get in front of more people who may be able to provide feedback.

6

Sounds good.
I can see the blue gray ground track when I propagate the satellite forwards in time.

7

I’m still stuck on this problem if anyone has ideas out there.

8

Perhaps you want this path overlap

[{

"id": "Satellite/Sat1/ECI",

"path": {

    "leadTime": 0   //first

}

},{

"id": "Satellite/Sat1/ECEF_footprint",

“path”: {

  "show": true,

  "leadTime": 0.0,

  "trailTime": 6660.0,

  "width": 2.0,

  "material": {

    "solidColor": {

      "color": {"rgba": \[0.0,255.0,255.0,255.0\]}   //  second

    }

  } 

}

}]

9

This solved my problem. I didn’t know that Cesium renders its paths not fully based on height. If both the satellite footprint and the satellite’s path are translucent, or both are solid, then it compares their heights. Though if one is translucent, it draws it above the other.
Thank you Fav1 for the sandbox!