Heatmaps Layer¶

The heatmaps layer renders weighted density fields over the surface. Each HeatmapDatum holds a collection of HeatmapPointDatum samples plus bandwidth and colour controls.

from IPython.display import display

from pyglobegl import (
    GlobeConfig,
    GlobeWidget,
    HeatmapDatum,
    HeatmapPointDatum,
    HeatmapsLayerConfig,
)

heatmap = HeatmapDatum(
    points=[
        HeatmapPointDatum(lat=0, lng=0, weight=1.0),
        HeatmapPointDatum(lat=10, lng=10, weight=0.6),
    ],
    bandwidth=0.8,
    color_saturation=2.5,
)

config = GlobeConfig(heatmaps=HeatmapsLayerConfig(heatmaps_data=[heatmap]))

display(GlobeWidget(config=config))

HeatmapDatum and HeatmapPointDatum¶

• HeatmapPointDatum — one sample with lat, lng, and weight.
• HeatmapDatum — a group of points plus bandwidth (kernel width) and color_saturation controlling how intensity maps to colour.

Custom colormap¶

By default the layer uses globe.gl's built-in colormap. To control it, pass a heatmap_color_fn — a frontend Python callback that maps a normalised density t in [0, 1] (0 is the lowest weight, 1 the peak) to a CSS colour string. globe.gl samples it at data-change time to bake the colour lookup, so it is not called per animation frame.

from pyglobegl import frontend_python


@frontend_python
def colormap(t):
    red = int(255 * t)
    return f"rgb({red},{int(90 * t)},{255 - red})"


config = GlobeConfig(
    heatmaps=HeatmapsLayerConfig(heatmaps_data=[heatmap], heatmap_color_fn=colormap)
)

Leave heatmap_color_fn as None (the default) to keep globe.gl's colormap. You can also swap it at runtime with GlobeWidget.set_heatmaps_color_fn(...), and passing None restores the default.