{
const height = width / 1.6;
const context = DOM.context2d(width, height);
const projection = d3.geoMercator().fitSize([width, height], isolines);
const path = d3.geoPath(projection, context);
for (const isoband of isobands.features) {
context.beginPath();
path(isoband);
context.fillStyle = z(isoband.properties.min_rtt.split("-")[0]);
context.fill();
}
return context.canvas;
}