Geodetic Control Point Data

July 13, 2017

Geodetic control refers to permanent reference markers placed in the ground and precisely marked, located and documented. These markers provide accurate reference points to support the production of consistent and compatible data collection for surveying and mapping projects. Wisconsin has tens of thousands of survey control monuments placed by numerous agencies over many decades, so the avenues for finding control point information are varied. 

Continuously Operating Reference Stations (CORS) Data

Surveyors, GIS users, engineers, scientists, and the public at large that collect GPS data can use CORS data to improve the precision of their positions. CORS enhanced post-processed coordinates approach a few centimeters relative to the National Spatial Reference System, both horizontally and vertically. 

Wetlands Data

The Wisconsin Wetland Inventory (WWI) regulatory maps show graphic representations of the type, size and location of wetlands in Wisconsin. These maps have been prepared from the analysis of high altitude imagery in conjunction with soil surveys, topographic maps, previous wetland inventories and field work.  The Wisconsin Department of Natural Resources (DNR) manages the WWI.

Land Use and Land Cover Data

Land cover and land use are often used as interchangeable terms, but each designates a specific type of information.  Land cover designates the vegetation or other type of cover that is on the land (grass, red oak, concrete).  Land use designates the human-derived applications and activities that take place on the land (agriculture, commercial, residential).  There are a variety of state and national products available that map the past and present land cover and/or land use of an area. 

Address Point Data

Address points are a valuable dataset for use in a variety of assessment, analysis and visualization tasks.  These points are most often maintained at the county jurisdictional level.  It should be noted that the general term “Address Points” can represent a variety of spatial locations.

Rivers, Lakes, and Streams Data

The most common source of hydrography (rivers, streams, lakes) data in Wisconsin is the Wisconsin DNR’s “24k hydro” database.  The DNR 24k hydro dataset is the most common starting place for most users in the state.  Because the DNR data are limited to Wisconsin, users who need entire watersheds that cross the state border should investigate the National Hydrography Dataset (NHD) maintained by the U.S. Geological Survey.

Flood Hazard Data

The Federal Emergency Management Agency is the federal agency ultimately responsible for flood hazard mapping in the United States.  While the Wisconsin Department of Natural Resources acts as a technical contractor for the mapping in Wisconsin, all data are distributed by FEMA.

School District Boundary Data

The majority of the 400+ school districts in the state don’t have a detailed, up-to-date map showing their exact boundaries in a digital format. They typically maintain the location of their school district boundaries using hard copy maps and/or some other format the district deems appropriate.