This visualization presents a 2D heatmap of the Old Faithful dataset, using a repeating grid of binned scatterplots for each pair of variables to reveal outliers. The interface includes a slider to adjust the maximum number of bins and an interval brush for selection, which highlights counts in green while unselected areas appear grey. The implementation loads data via `d3.csv` and renders the Vega-Lite specification with `vegaEmbed`, leveraging the vega-lite API and D3 v4 for interaction.