Heatmap: Max radiusPixels or expression in other units

Target Use case

I am currently in a situation, where I want to control the radiusPixels to be as accurate as possible to a meter value in real-world terms.

Currently the maximum pixel value is 100 as seen here:

https://github.com/visgl/deck.gl/blob/60e9334b3e4705b30b650cfb5445fb2d88851b6e/modules/aggregation-layers/src/heatmap-layer/heatmap-layer.js#L62

Before seeing this limitation, my idea was to increase/decrease the radiusPixels based on zoom level:

const getMetersPerPixel = (latitude: number, zoomLevel: number) => {
  const earthCircumference = 40075017;
  const latitudeRadians = latitude * (Math.PI / 180);
  return (
    (earthCircumference * Math.cos(latitudeRadians)) /
    Math.pow(2, zoomLevel + 9)
  );
};

const getMetersInPixelValue = (
  latitude: number,
  meters: number,
  zoomLevel: number
) => {
  return meters / getMetersPerPixel(latitude, zoomLevel);
};

Proposed feature

Being able to control the value as either meter, kilometer or pixel where pixel would be the default value, where the heat-map would automatically adjust for zoom. Alternatively, it could stay as pixels but being able to handle values above 100.

To Do List

• Add label and assign to milestone
• Coding
• Doc update
• What’s new update
• Test

Start with modules/aggregation-layers/src/heatmap-layer/heatmap-layer.js at the radiusPixels limit cited in the issue. First resolve whether the scope is unit-aware radius values or pixel values above 100; done should include the agreed behavior, implementation, documentation, and tests listed in the issue.