This metadata record describes the 1 foot contour data used for the 2016 Connecticut LiDAR project covering approximately 5240 square miles.
To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments, and hydrologic modeling. LAS and bare earth DEM data products are suitable for 1 foot contour generation. USGS LiDAR Base Specification 1.2, QL2. 19.6 cm NVA.
Project Projection, Datums and Units. Projection - State Plane Connecticut. Horizontal datum - North American Datum of 1983 (NAD83 (2011)). Vertical datum - North American Vertical Datum of 1988 (NAVD88) using the latest geoid (Geoid12b) for converting ellipsoidal heights to orthometric heights. Units - US feet
ground condition
This data is for planning purposes only and should not be used for legal or cadastral purposes. Any conclusions drawn from analysis of this information are not the responsibility of Sanborn Map Company. Users should be aware that temporal changes may have occurred since this dataset was collected and some parts of this dataset may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations. Contact: State of Connecticut
241 Main Street
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Data covers the boundary extents provided for the project.
A visual qualitative assessment was performed in the source Lidar dataset.
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The tile definition defines discreet non-overlapping rectangular areas used as cut lines to break up the large classified lidar dataset into smaller, more manageable data tiles. Each tile is 2500 X 2500 feet in dimension.
Terrain geodatabase comprised of lidar bare earth DEM and hydrologic breaklines used to derive 1 foot contours.
At selected locations throughout the site, accurate GPS coordinates and elevations are surveyed and the points are marked with targets.
New LiDAR data is captured for the project area using a Leica ALS70 LiDAR instrument an integrated IPAS20 GPS/INS system mounted within a Aero Commander twin engine airplane.
The airborne GPS data is post-processed in Inertial Explorer software and LEICACloudPro software to determine the LiDAR sensor's angle and orientation in the terrain (project) coordinate system and datums during the survey.
The georeferenced lidar data is then classified and edited in Terrasolid Terrascan software. Data is classified to produce: Class 1: unclassified, Class 2: ground, Class 7: low point, Class 9: water, Class 10: ignored ground, Class 17: bridge deck, Class 18: high noise.
Classified Contour Keypoints from LiDAR and hydro-flattened breaklines were used to create a terrain to generate of 1 foot contours. Smoothing was applied to the contours for more aesthetically pleasing contours without affecting accuracy of the contours. The contour data was cut into tiles for topology corrections. The contour data was then subjected to manual quality control review by Sanborn including checking for tile edge matching.
1 foot contours
USGS Base Specification 1.2, QL2 meeting 19.6 cm NVA
241 Main Street
The Capitol Region Council of Governments digital data have been tested and their documentation carefully reviewed. However, the Capitol Region Council of Governments and its representatives make no warranty or representation, either expressed or implied, with respect to the digital data and their documentation, their quality, performance, merchantability, or fitness for a particular purpose. The digital data are distributed on "as is" basis, and the user assumes all risk to their quality, the results obtained from their use, and the performance of the data. In no event will the Capitol Region Council of Governments or its representatives be liable for any direct, indirect, special, incidental or consequential damages resulting from and defect in the State of Connecticut or in their documentation. This disclaimer of warranty is exclusive and in lieu of all others, oral or written, express or implied. No agent or employee is authorized to make any modification, extension, or addition to this warranty.
Capitol Region Council of Governments
1935 Jamboree Dr