Why does geoscatter run slowly with additional points overlayed?

I am using App Designer R2023a to build a GUI that uses geoscatter & colormap to plot 1hz data in realtime from a mobile lab. Using hold("on") each new point is overlayed on the map, and initially this works fine. But after several hundred overlays the app runs slower, takes up more RAM, and consumes more CPU power on my W10 machine. This prevents the app from completing acquisition and processing of the incoming data within the next 1000ms.

I know geoscatter can handle tens of thousands of points on a single map, but it is the overlay process that seems to bog it down after a few hundred points. Attached is the stripped down code that overlays a single point at 200ms intervals. Curiously, the time to complete the overlay function remains less than 20ms; this is displayed at the top of the map. The number of points initially plotted can be changed on line 74; using 1 or even 20000 initial points does not seem to make a difference in the number of overlays geoscatter can handle.

Using the compiled app helps only somewhat with this problem.

Is there a better way to handle these incoming points other than using hold("on")? Is there an error in the code?

Thanks, pk

Answer 1

[Ayush]

Hey Paul,

I understand that you are facing issue with App Designer GUI when using ‘geoscatter()’ and ‘colormap’ functions. Because of this app starts to slow down, consume more RAM and use more CPU power after several hundred overlays which prevents the app from data acquisition and processing within the required time frame.

Can you please provide us with the code you are mentioning about in the query?

Meanwhile, you can try out the following workarounds for the problem you are facing:

1. Plotting in chunks: Instead of overlaying points individually, you can accumulate a certain number of points and plot them as chunks. For example, you can collect 100 points and plot them together using ‘geoscatter’.
2. Try asynchronous processing as it might be beneficial to offload data acquisition and processing tasks as separate threads or processes.
3. You can also refer to geoscatter documentation for further information : Scatter chart in geographic coordinates - MATLAB geoscatter - MathWorks India

Hope this helps!!

Regards,

Ayush Goyal

[Paul]

Thanks Ayush.

I have reduced the number of times I update the plot by averaging and updating on a ten second basis. That helps, but I still get the problem, just after more points. I also stop plotting when that tab is not open.

I also tried asynchronous plotting, but that was no help.

It seems to work ok now, but it seems there should be a cure to running geoscatter hundreds of times to add additional points.

Thanks, pk