Lidar Data for Wisconsin: A Guide to the State's Elevation Data

Lidar coverage and source dates vary across Wisconsin. Check your site against the USGS 3DEP work-unit index; an unavailable lookup means coverage is unknown. This guide explains what lidar is, how Wisconsin was flown, what the data covers and how you can use it for contour maps, elevation profiles and 3D terrain models without specialist GIS software.

What is lidar?

Lidar stands for light detection and ranging. A scanner fires rapid laser pulses and times how long each one takes to come back. Combined with the aircraft's GPS position and an inertial measurement unit, every return can be placed precisely in three dimensions.

Almost all of Wisconsin's lidar is airborne: a scanner under a plane or helicopter sweeps the ground in overlapping strips. The result is a point cloud — millions or billions of points, each with an easting, a northing and an elevation, plus attributes such as return intensity and classification.

What makes lidar so valuable for terrain is that one pulse can produce several returns. The first may hit the top of a white pine; the last may reach the ground beneath it. Keeping only the ground returns gives a bare-earth digital elevation model (DEM) that shows the true shape of the land, even under the dense forest of the Northwoods.

Wisconsin's lidar program

Wisconsin's lidar has been flown project by project, many of them county by county, at different times and to different specifications. The State Cartographer's Office keeps a directory of Wisconsin elevation and lidar data, including county lidar products. Each project's own metadata gives its date, cell size and reported accuracy.

At the national level, the USGS 3D Elevation Program (3DEP) gathers lidar into one seamless bare-earth model of the United States, and it is the model every elevation on this site comes from.

Lidar coverage in Wisconsin

Ground elevations come from the USGS 3D Elevation Program (3DEP) seamless bare-earth model, with elevations above NAVD 88. Source cells are 3.3 ft per pixel in the finest work units, with about 9.8 ft per pixel and 33 ft per pixel sources elsewhere. USGS elevation data is public domain. Lidar coverage and source dates vary across Wisconsin. Check your site against the USGS 3DEP work-unit index; an unavailable lookup means coverage is unknown. The projects differ in age and point density, and the USGS index can list more than one lidar work unit for the same place. More from the USGS 3D Elevation Program and Wisconsin elevation resources.

For any specific address, the lidar coverage page shows whether a lidar work unit covers it and which work units the USGS 3DEP index lists there, with their year and other details where the index records them.

Accuracy and resolution

Vertical accuracy

Accuracy depends on the source project, its date and how well ground was measured; this site does not assign one accuracy figure to all Wisconsin. Source cells range from 3.3 ft per pixel in the finest work units to about 9.8 ft per pixel or 33 ft per pixel in coarser sources. Every download reports the share outside the finest lidar work units, or says coverage is unknown if the index cannot be reached. Bare-earth elevations exclude buildings and tree canopy and do not replace a surveyed elevation for legal or engineering decisions.

Point density

Point density is how many laser pulses were recorded per square foot. It decides how much terrain detail survives under trees and how sharply small features such as ditches, curbs and retaining walls show. Each project's metadata gives its pulse density, and the coverage checker shows it for the point you search where the USGS index records it.

Ground classification

A raw point cloud contains returns from everything: trees, buildings, power lines, vehicles and the ground. Points are classified so the ground returns can be separated from everything above them. The ground returns become the bare-earth DEM; the full cloud becomes the surface model that includes trees and structures.

DEM resolution

Where lidar exists, the 3DEP seamless model is 3.3 ft per pixel: each cell is 3.3 ft on a side. That is fine enough to show drainage ditches, terrace edges and individual landforms that disappear on coarser satellite-derived models.

How to get Wisconsin lidar data

Option 1: raw data (for GIS professionals)

The National Map Downloader serves 3DEP DEM tiles and lidar point clouds (LAS/LAZ), and the State Cartographer's Office directory points to county lidar products. Working with the raw data takes:

• GIS software such as QGIS or ArcGIS Pro, or point-cloud tools for LAS/LAZ files;
• an understanding of coordinate systems and datums, because tiles, mosaics and your own data may each use a different projection and unit (metric or US feet);
• disk space and processing power, because point clouds are very large;
• tile management, because data is distributed as tiles that you download, merge and clip yourself.

Option 2: processed results in Wisconsin Elevation Tools (for everyone)

Select an area on the map and choose what you want. You can:

• generate contour lines at any interval from 1 ft and download them as GeoJSON, DXF, PDF, KML or SVG;
• create elevation profiles for trails, rides and any line across the land;
• export 3D terrain models as STL or OBJ;
• download the DEM itself as a GeoTIFF;
• add elevation to GPX files and other GPS formats.

What you can do with lidar elevation data

Contour lines

Lidar supports contours at intervals far finer than those printed on published topographic maps, down to 1 ft — the detail needed for building pads, driveways and drainage.

Elevation profiles

Draw a line and read the ground along it. Hikers use profiles to judge a climb up the Devils Lake bluffs; engineers use them for roads, pipelines and fence lines.

3D terrain models

Turn any area into a printable model — the Baraboo Hills, a Driftless Area coulee, or your own valley.

Flood and hazard work

Fine elevation data underpins flood modeling and shoreline and bluff studies. This site's Water & Drainage tool shows where water would run and pond on the ground surface.

Land planning and building

Builders, architects and landowners use lidar to understand a site before design starts: earthwork, building pad placement, stormwater and views. It helps you prepare for a building permit conversation with the county planning department; it does not replace a survey where one is required.

Forestry and ecology

Because lidar measures both the ground and the canopy, it is used to map tree heights, streams, wetlands and erosion — useful across Wisconsin's forest land.

Lidar versus other elevation sources

Global satellite models cover the whole planet but at roughly 100 ft per cell or coarser, and many record the top of the forest rather than the ground. Good for a regional overview, not for site work.

Consumer GPS gives an altitude from satellite geometry or a barometer, and it is usually the least accurate part of a recorded track, especially in valleys and under forest.

Lidar (USGS 3DEP) gives true bare-earth elevation through vegetation at 3.3 ft per pixel. For any serious terrain work in Wisconsin it is the right source.

Using lidar without GIS software

Historically, using lidar meant specialist software, large downloads and a good grasp of projections. Wisconsin Elevation Tools removes those steps. You do not need to:

• download gigabytes of point clouds or DEM tiles;
• install QGIS, ArcGIS or any other GIS software;
• understand coordinate systems, datums or metric-versus-feet units;
• manage tile indexes or merge datasets;
• run geoprocessing workflows.

Pick an area, choose the output and download it. That puts lidar within reach of hikers, landowners, students, architects and anyone else who needs accurate terrain information.

Licensing

USGS 3DEP elevation data is a U.S. Government work in the public domain: you may use it, including commercially. A credit to the USGS 3D Elevation Program is appreciated. County lidar products carry each county's own terms and credit. Every file from Download Data carries the USGS credit.

Frequently asked questions

Related guides

• Contour lines for Wisconsin — generate contour maps from lidar.
• Topographic maps of Wisconsin — custom topo maps with lidar detail.
• Download DEM data for Wisconsin — the elevation model itself.
• Hiking elevation profiles — profiles for trails and routes.
• Add elevation to GPX files — replace GPS altitude with lidar elevation.
• Download terrain as STL — 3D printable terrain from lidar.