point clouds

Change in surface height explorer

June 24, 2025 by cartography Leave a Comment

Can we detect changes in surface height over time, at a neighborhood scale? The changes in heights represent the loss and growth of trees, buildings, and other features of the built environment.

KyFromAbove has multiple phases of lidar point clouds for Kentucky as open data. In this interactive map of Lexington, Kentucky (inside New Circle), we demonstrate how to visualize and explore these changes in surface height between 2010 (Phase 1) and 2019 (Phase 2) lidar point clouds.

While most point clouds are colorized by aerial photography to give a realistic view of the surface, this project uses a different approach. Points are colorized by the amount of change in surface height between the two phases. The color scale is from red (decrease in height) to blue (increase in height). Both phases are shown simultaneously with the ability to toggle the visibility of each phase.

View the interactive Potree scene viewer (which is VR-enabled) through this website:

contig.us/hawaii/lex-change

Below are some screenshots of the viewer focused on Kentucky Proud Park at the University of Kentucky campus.

Phase 1 decrease in height

Phase 2 increase in height

Phases combined

Phase 2 colorized with aerial photography

Filed Under: News Tagged With: digital surface model, dsm, height, kyfromabove, point clouds, uky geography, web maps

Shaded relief and 3D visualization in the browser

March 17, 2025 by cartography Leave a Comment

KyFromAbove has long produced elevation datasets for the public. Using their Phase II lidar point clouds, we created a new shaded relief and DEM raster tile sets for web mapping. While most mapping applications focus on ground elevations, we use the above-ground elevations to make a digital surface model (DSM). These elevations show buildings, trees, and even cars.

These above-ground elevations, however, have unique challenges. The latest project attempts to minimize errors and create visually impactful shaded relief and RGB terrain layers from DEMs for elevations.

Check out the preview here: outrageGIS.com/maps/new-circle

Lexington’s UKy campus

Filed Under: Free Maps, Maps Tagged With: digital mapping, kyfromabove, lidar, point clouds, uky geography

Terrain Explorer

May 30, 2024 by cartography Leave a Comment

In this web map, we explore how to use different elevation models in 3D maps. The KyFromAbove project collects and maintains high-resolution elevation data and aerial imagery for Kentucky. The bare-earth Digital Elevation Model (DEM) was created from a lidar point cloud. This is the typical elevation model that we use. The same point cloud was then filtered to create a Digital Surface Model (DSM) showing above-ground elevations, like buildings and trees. Both of these elevation models were converted to terrain tiles to use in web mapping applications. MapLibre GL JS 3D features terrain rendering with RGB-encoded elevation raster tiles.

The sliders allow the viewer to change the vertical exaggeration of the DEM and DSM. If geolocation is enabled, a track will record the viewer’s location. That track can be downloaded as a GeoJSON (works in Chrome).

Visit the page: outragegis.com/terrain-explorer/

This was a project in the UKy Geography MAP 675, a course in the department’s Digital Mapping MS graduate program. The aerial imagery and elevation data are from 2019.

Filed Under: Free Maps, Maps Tagged With: lidar, point clouds

Sheltowee Trace elevation profile

July 6, 2020 by cartography Leave a Comment

Working on the 2020 update of the Sheltowee Trace maps using high-resolution DEMs derived from lidar point clouds. An elevation profile was created by sampling elevation every 264 feet along the 343-mile trail. This profile shows the proposed extension from Burnt Mill bridge to Rugby.