Where the shadows fall

What you are looking at

Every dot is a laser return from the USGS 3DEP lidar flight over the NREL Flatirons campus west of Broomfield, Colorado. No map symbols. The six research turbines, the met towers, the buildings and the mesa edge are all just the shape the returns make. Each return is colored by its elevation, so the mesa reads as a rise and the turbine tips are the brightest thing in the cloud. The aerial photo flown the same spring is one toggle away. The ground under it is the 1 m lidar terrain model. Zoom in and the cloud sharpens: the page pulls the deeper octree levels only for what is in view.

Points in file--

Points on screen--

Detail level--

Bytes fetched--

Tallest return--

Controls

Color by

Basemap

Splat size0.60

Point budget6M

Slow orbit

How it streams

The file is a cloud optimized point cloud (COPC), an octree where each deeper level adds more of the returns. The browser reads the index with one HTTP range request, keeps the coarse levels for the whole site, and fetches the deepest level only where the camera is looking. Decompression is LAZ in WebAssembly. Full density here is level 6, about 13 returns per square meter. Each point is drawn as a disc sized to the spacing of the finest level in view, so surfaces close up as the camera gets near. The page opens with the camera inside the returns of one cottonwood on the creek and pulls back along the hero view's own line of sight, so the dots become a tree, then the creek, then the site.

Replay the flight runs the survey back in the order the aircraft recorded it. The plane flew four passes over the site between 10:44 and 11:28 am on May 29, 2020, each about 45 s over the window, with 6 to 18 minutes between them while it flew lines elsewhere. The rotors kept turning between passes, so the blades land in a different place on each one. Every return is real; they were just recorded minutes apart.

Preparing

Elevation

lowest returnhighest

Elevation

Photo

Height above ground

Return intensity