CesiumGS / CesiumGS/cesium

KML GroundOverlay Georeferencing in 3D View at High Latitudes

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#12,943 4 comments 0 reactions 0 assignees View on GitHub
category - kml needs triage type - bug
Dominant language
JavaScript
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Description

### What happened?

When testing KML's [GroundOverlay](https://developers.google.com/kml/documentation/kmlreference#groundoverlay), georeferencing does not align correctly in 3D views at higher latitudes. Google Earth also uses a 3D view, but it renders the overlay as expected.

The reproduction steps demonstrate comparing Cesium 3D view vs. Cesium 2D view vs. Google Earth 3D view.

### Reproduction steps

[GroundOverlay-Examples.zip](https://github.com/user-attachments/files/22802778/GroundOverlay-Examples.zip)

1. Download the above `GroundOverlay-Examples.zip` and unzip.
2. Load an attached KMZ file (`GroundOverlay.kmz` or `GroundOverlay-RedOnly`).
3. If loading `GroundOverlay.kmz`, disable the blue layer. (Does not apply if loading `GroundOverlay-RedOnly`.)
4. For "Imagery", select "Bing Map Aerial" or any other imagery that clearly shows North America.
5. Ensure that it is in "3D" mode.
6. Zoom in near the coast of New York City and observe how the red layer does *not* line up with the coastline.


Image

7. Change to "2D" mode.
8. Zoom in near the coast of New York City and observe how the red layer now lines up well with the coastline.


Image

(Optional)
1. Load Google Earth and load the attached KMZ file(s).
2. Zoom in near the coast of New York City and observe how the red layer does line up well with the coastline, despite being in a 3D view.


Image

### Sandcastle example

https://sandcastle.cesium.com/#c=bY+xTsMwEEB/5ZQplSJbrDSNkFqJpVUHKqYsrnMpFhc7ss9pA+LfiRsQCOrtnt+zztrZwDAYPKOHFVg8wxqDiZ14vrK8zvR1XjvLylj0dbZY1ra2cyPwwmib/Cua4car08a7fmcuxhbwPumsCZXf24TvoVUUsEi4pfHgvjH7mChMR0rQpLr+4B69i7b5aT4Wy6zIysAjYTXLAA+m651niJ5yISRj15NiDPIY9Suy0CGkrZNayt9p2ZgBTLO68c20QAjTTRuJnswb1llVysn/l5JTjbGn/YCe1Ji0l7tqO0MhRCmn8XbJztFR+T8vfwI

### Environment

Browser: Microsoft Edge
CesiumJS Version: 1.134.0
Operating System: Windows 11

Contributor guide

Open the contributing guide

Research direction

Start with the linked Sandcastle example and the attached GroundOverlay KMZ files, then compare the 3D and 2D rendering paths near New York City at high latitude. Done means the GroundOverlay aligns with the coastline in Cesium's 3D view as it already does in 2D and Google Earth.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript
Domain
computer-graphics
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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