London bus routes overlaid. Simple heatmap generated with yellow lines and a multiply blending mode in QGIS.
Glasgow 3D Residential Property Density QGIS2threejs
Made using the excellent QGIS2Three.js plugin.
Legend actually refers to property count rather than density.
For more information see Anita Graser’s post: http://anitagraser.com/2014/03/15/3d-viz-with-qgis-three-js/