surf.sampleGrid.delaunayTriangulate(), new WTWD.IsolineMetric());
List<IsochroneData> isochrones = new ArrayList<IsochroneData>();
for (int minutes = spacing; minutes <= surf.cutoffMinutes; minutes += spacing) {
int seconds = minutes * 60;
WTWD z0 = new WTWD();
z0.w = 1.0;
z0.wTime = seconds;
z0.d = 300; // meters. TODO set dynamically / properly, make sure it matches grid cell size?
IsochroneData isochrone = new IsochroneData(seconds, isolineBuilder.computeIsoline(z0));
isochrones.add(isochrone);