Performance differences due to distance

[omar]

Thanks for putting together this Sandcastle example! I’m actually not seeing this performance different. I modified it slightly to display the FPS. On my laptop I’m seeing 30 FPS regardless of whether “near” or “far” is shown.

Can you tell me what FPS you’re seeing for each case? Or is the slow-down you’re referring to the initial start-up time to create these lines?

@samueladdison

Obviously these are huge numbers, and you might expect Javascript to run into issues there, but it’s odd that plotting a single point at that distance from the Earth is fine, but drawing a line is not.

I think the different in drawing that line vs drawing a very far away point is that a polyline is subdivided along its length (typically to accurately visualize a line that curves around the Earth). One thing to consider here is to set the arcType to “none” (see Global - Cesium Documentation), otherwise the granularity parameter controls this subdivision: PolylineGraphics - Cesium Documentation.

Let me know if this helps.

@samueladdison

The data comes from a NASA feed at https://sscweb.sci.gsfc.nasa.gov/ - it provides historical data going back decades, but also predictive data for a heap of satellites currently orbiting.

This is very cool - thanks for sharing this! The only dataset I was aware of current locations of satellites was the data from Celestrak (https://celestrak.com/) which provides it as TLEs, that I think requires using software like STK to convert those readings into paths that you can render in CesiumJS.