Line of Sight Between Two Points in Wisconsin
Will the new deck see the lake? Can the barn camera see the gate? Does the wireless link clear the ridge? Tap two points and see the ground between them with the sightline drawn over it.
Check a line of sight now
Tap the observer, tap the target, choose Done. The answer is clear or blocked, and where.
Open Sightline →One view, answered exactly
A viewshed shows everything visible from a point. Often the question is narrower: can this spot see that one. A house site and a view of Lake Michigan, a window and the river below a Mississippi bluff, a deck on the East Bluff above Devils Lake and the far shore, a farmhouse and a neighbor's new building. Sightline answers that question for one pair of points, and says how close it is.
What people use it for
- Views from a house site. Check the view a listing promises, or which of two building spots keeps the lake in sight.
- Privacy. Whether a road or a neighbor can see a proposed building: put A on the road at eye height and B on the building at its roof height.
- Wireless and radio links. Terrain clearance between two antenna sites for rural internet or a farm network.
- Cameras and lights. Whether a camera on the barn can see the gate at the end of the lane.
- Hiking and photography. Whether one overlook can see another, or a landmark, before you make the climb.
How to check a line of sight
- Open Sightline and tap the observer (A), then the target (B). Undo point removes the last tap. Choose Done.
- Set the heights. Eye height at A is how high the viewer, the window or the antenna is above the ground; target height at B is the height of the thing you want to see, or 0 for the ground itself.
- Choose what blocks the view. Terrain only, or, in Brown County, Trees & buildings (Brown County) to use the county's surface model.
- Read the result. The panel says B is visible from A or B is hidden from A. When visible, it gives how much the line clears the ground at the tightest point; when hidden, how far from A the view is blocked and how far below the ground the line passes.
- Adjust and compare. Move the height sliders and the result updates. New line starts again.
Below the result, the chart draws the ground between A and B with the sightline over it, so you can see whether the block is a ridge in the middle or a small rise right in front of you. The panel also gives the ground elevation at A and B and the resolution of the terrain behind it.
Widen the question
Sightline checks one line. These look at the whole view and the ground along it.
Reading a blocked result
Blocked close to A
If the view is blocked near the observer, the obstacle is usually the edge of the slope you are standing on. Stepping forward to the brow, or raising the eye height a little, as a second-floor window or a deck would, is often enough. Try it with the slider.
Blocked in the middle
A ridge or a rise between the two points. The amount it blocks by tells you how much higher A or B would need to be to clear it: a few feet is a tall deck or a mast; a lot is a different site.
Clear by a small margin
A clear line that passes just over the ground can still be blocked by what stands on it. Outside Brown County the check is over bare ground, so a woodlot, a hedge or a barn between the points is not counted. Look at the aerial basemap along the line before you rely on it.
Trees, buildings and Brown County
The only surface model this site reads is Brown County's, which records trees and buildings as they stood when the lidar was flown. In Brown County, the Trees & buildings option lets them block the line, and the panel says how much of the line the surface model covers. Everywhere else in Wisconsin, Sightline uses bare earth: the answer is about the terrain, not what grows or stands on it.
About the data
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. Earth curvature and standard atmospheric refraction are applied along the line. More from the USGS 3D Elevation Program and Wisconsin elevation resources.
Frequently asked questions
How do I check the line of sight between two points?
Open Sightline, tap the observer (A), then the target (B), and choose Done. Set the eye height at A and the target height at B. The panel says whether B is visible from A, draws the ground between them with the sightline over it, and, if the view is blocked, how far from A it is blocked and by how much.
Does it include trees and buildings?
Only in Brown County, and only if you choose Trees & buildings (Brown County). That option uses Brown County’s surface model, with trees and buildings as they stood when the lidar was flown. Everywhere else in Wisconsin the check is over bare ground, so trees and buildings do not block the line.
Does it allow for the curve of the earth?
Yes. Earth curvature and standard atmospheric refraction are applied, so distant ground drops slightly below the line as it does in reality. Over a long view across a lake or a wide valley this matters.
What does blocked by a number of feet mean?
It is how far the line passes below the ground at the tightest point. Raising the observer or the target by about that much would just clear the terrain there. Move the height sliders and the result updates.
Can I use it for a wireless or radio link?
For the terrain, yes: put A and B on the two antenna sites and set each height to the antenna height. It checks the straight line only; a radio link also needs clearance around the line, and trees outside Brown County are not counted, so treat a narrow clear result with caution.
What if I tap more than two points?
The first and last points are used as A and B, and the panel says so.
Related guides
- Elevation profile generator — the ground along any line.
- Terrain checks before buying rural land — views as part of the pre-offer pass.
- Elevation profiles for hiking — plan the climb to the overlook.