This heatmap demonstrates global population distribution using a textured choropleth map. Each country is filled with a circle pattern whose density increases with population size, using six threshold-based visual levels. The visualization employs D3.js v4 with the `d3.geoMercator` projection and `d3.geoPath` to render world GeoJSON boundaries, while the `textures` library generates varying circle sizes for the fills. Population data comes from a CSV file matched to country codes, with color thresholds defined by `d3.scaleThreshold` and ranges from sparse to dense circle patterns.