Hi Chris This answer might be a bit late, but here is the way I did what you want to achieve: The SceneView of the API has the toScreen() function, which takes any 3D point on the map and returns that point's [x, y] pixel coordinates on the viewport (x is measured from the left edge of the screen and y from the top edge). So, whenever the camera changes, you can call toScreen() for every HTML marker element you have and update the marker's position on screen accordingly via CSS. If you want to test whether a marker is still on the screen, you can access the viewport's extends via the size property of the SceneView. Compare the marker's x and y coordinates to the viewport's size and decide whether the marker should still be displayed or not. I hope this helps.
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