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DSM
DEM

Elevation Explorer

Kentucky Division of Geographic Information

The Elevation Explorer allows you to query and download the highest and lowest elevations (and highest above-ground object) within a specified area in your browser's window. A green bounding box is placed over the map to indicate the current calculated extent. Check the edges of the bounding box because the elevations might be on the edge.


How to use

  • 1Zoom and pan the map to your area of interest. The current window extent is used as the bounding box.
  • 2Select the desired base map from the Map Layers menu. Phase 1 and Phase 2 surfaces have a swipe user interface to compare the DSM and DEM.
  • 3Select a surface on which to calculate elevation and optional Height mode from the toolbar. Note: To use Height mode, select a DSM surface.
  • 4Click Go to query elevation within the view.
  • 5At zoom < 15, pre-computed spot elevations are used. At zoom ≥ 15, the raster surfaces are queried directly.
  • 6Results are placed on the map and saved to browser storage, which can be downloaded using the buttons below.

Legend

Max elevation (DEM)
Min elevation (DEM)
Max elevation (DSM)
Min elevation (DSM)
Max height (tallest object)
Highest spot elevation
Lowest spot elevation
DEM Digital Elevation Model. Represents bare-earth ground elevation.
DSM Digital Surface Model. Includes structures, vegetation, and other features above the ground.
Phase 1 data is 5-ft resolution; Phase 2 is 2-ft resolution.

Storage

Results are saved to browser storage automatically. A GeoJSON will contain the extent of each query as a polygon feature and the elevation and height values as point features. The Clear button on the main page will hide stored features (refreshing the page will show them again). The Clear Storage button below will permanently remove all stored features.

Spot elevations (zoom < 15)

At lower zoom levels, pre-computed spot elevations are used instead of querying the raster directly. The highest and lowest elevation points have been evaluated in each 5K grid cell statewide (Phase 2 DEM only).

All grid cells that intersect the view are included. Because partial grid cells at the edges are counted, the highest or lowest point may fall outside the visible extent. The green footprint shows the full area that was evaluated.

If no grid cells intersect the view, the raster is queried directly as a fallback. If the visible area exceeds 5 square miles, spot elevations are used even at zoom 15 and above.

Zoom to level 15 or closer and keep the view under 5 sq mi to use all surfaces, height mode, and direct raster queries.

Height mode

When enabled on a DSM surface, height is calculated as DSM − DEM, representing the tallest object above ground within the bounding box. Available at zoom 15 and above.

Caveats

The elevation queries return two values for maximum and minimum elevations in the search area. If there are duplicate values, only the first occurrence will be displayed and saved. For example, searching for elevations over open water should return the elevation of the water surface as one value. For height mode, the same applies. Triangulation artifacts may occur near the shore and banks of water bodies in the DSM.

About

This tool was developed by the Kentucky Division of Geographic Information (DGI) using KyFromAbove elevation data. This tool use multiple services hosted by DGI, including raster services for the DEM and DSM data, a feature service for pre-computed spot elevations, and a geoprocessing service to calculate elevation statistics.

KY DGI