Connecticut 20 FT Contours is line feature-based data representing ground elevation at 20 ft intervals for Connecticut. This information was obtained from the University of Connecticut, College of Agriculture and Natural Resources and is a Beta product intended for research and demonstration purposes. The data is not consistently accurate statewide. In some areas there are anomalies with the contour line information due to data gaps in the underlying LiDAR data used to generate the contour lines. This is a known limitation of the LiDAR data collected for Connecticut in 2000. Areas where the contours are incorrect are typically easy to recognize because, in relation to nearby contours, they appear too straight and angular, do not naturally curve as expected, or don't exist where they probably should. Also, contour lines may not conform very well to the shoreline of waterbodies and in many instances erroneously extend into areas of water.

Due to the anomalies in the data, use caution when viewing and analyzing this information.

Attribute information consists of fields used to classify and label features based on 20 and 100 ft contour intervals.

Connecticut 20 FT Contours are used to depict ground elevation at 20 ft intervals or greater. Each contour line represents a line of equal elevation and indicates surface relief when used with other information such as aerial photography, soils, geology, or hydrography.

Go to http://clear.uconn.edu for additional information on the LiDAR-derived data products generated from Connecticut's 2000 statewide LiDAR coverage.

Aero-Metric, Inc. of Sheboygan Wisconsin was contracted by the State of Connecticut to provide the 2004 Statewide Aerial Survey of Connecticut. Contract deliverables include digital orthohotos, two sets of non-rectified prints for stereoscopic viewing, photo indexes, and LiDAR data. All 2004 Statewide Aerial Survey imagery and data products are defined under State of Connecticut contract award number RFP-990-A-14-0518-C (dated Feb 22, 2000), including contract award supplement #1 (dated Feb 28, 2002), contract award supplement #2 (dated Nov 4, 2004), contract award supplement #3 (dated Nov 26, 2004) and contract award supplement #4 (dated May 13, 2005). TerraPoint LLC of Woodlands Texas was subcontracted to create a Connecticut Statewide LIDAR dataset. Through funding by the Connecticut Joint Highway Research Council, project JH07-02, statewide LiDAR-derived datasets were subsequently created and made accessible by Associate Professor Thomas Meyer of the University of Connecticut, College of Agriculture and Natural Resources, Department of Natural Resources and the Environment. These derived data products include tiled point clouds, TINS, DEMs, and contour shapefiles available by USGS topographic quarter-quarter quadrangle area. CT DEP subsequently appended the statewide contour shapefiles into statewide datasets of 2, 10, 20, 50, and 100 foot intervals.

collection date

None. No restrictions or legal prerequisites for accessing the data. The data is in the public domain and may be redistributed.

None. No restrictions or legal prerequisites for using the data after access is granted. The data is suitable for use at appropriate scale, however these data are not consistently accurate statewide. In some areas there are anomalies with the contour line information due to data gaps in the underlying LiDAR data used to generate the contour lines. This is a known limitation of the LiDAR data collected for Connecticut in 2000. Areas where the contours are incorrect are typically easy to recognize because, in relation to nearby contours, they appear too straight and angular, do not naturally curve as expected, or don't exist where they probably should. Also, contour lines may not conform very well to the shoreline of waterbodies and in many instances erroneously extend into areas of water. Due to the anomalies in the data, use caution when viewing and analyzing this information. Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut as the source for this information.

Includes 20 foot ground elevation contour line features. Information encoded about these features includes an ELEVATION_FT attribute and attributes for selection and cartographic symbology classification. Use the INTERVAL_FT attribute to select and symbolize features on a map. Use the ELEVATION_FT (for 2 foot contours), LABEL_10FT, LABEL_20FT, LABEL_50FT and LABEL_100FT attribute fields to label elevation values on a map. To define a layer that only includes 10 foot contour interval features, query LiDAR 2000 Contour features for INTERVAL_FT value equal to 10 or INTERVAL_FT value equal to 20 or INTERVAL_FT value equal to 50 or INTERVAL_FT value equal to 100. This selects the elevations that are divisible by 10. Similarly use  INTERVAL_FT value equal to 20 or INTERVAL_FT value equal to 100 to select 20 foot contours, INTERVAL_FT value equal to 50 or INTERVAL_FT value equal to 100 to select 50 foot intervals, INTERVAL_FT value equal to 100 to select 100 foot intervals. The selected intervals can be used to cartographically represent the contour lines or add an elevation label to certain contour lines.

20 FT ground elevation contours represented as line features

State of Connecticut, Department of Environmental Protection

Line features conform to the following topological rules. Lines are single part. There are no duplicate lines. Lines do not self overlap. Lines do not overlap other lines. Lines intersect only at nodes, and nodes anchor the ends of all lines. Lines do not overshoot or undershoot other lines they are supposed to meet and intersect. The tests of logical consistency were not performed by CT DEP. No automated procedures or tests were performed by CT DEP to guarantee desired topology other than limited visual inspection.

The completeness of the data reflects the feature content of the data sources, which include the LiDAR 2000 contour shapefiles and the LiDAR 2000 elevation points. The LiDAR 2000 Contours layer contains automatically generated contour lines that may contain errors or inconsistancies inherent in the automated process. The LiDAR 2000 Contours layer contains errors or inconsistancies related to errors inherent in the original LiDAR elevation data capture. There are no plans to update or correct these data.

The LiDAR 2000 Contours layer retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and obtained from the LiDAR 2000 contour shapefiles. All attributes have valid values. Values are within defined domains. ELEVATION_FT attribute values are inherited from the LiDAR 2000 contour shapefiles. Attribute INTERVAL_FT was populated through successive selections of ELEVATION_FT values based on calculations to select values for 10 foot, 20 foot, 50 foot and 100 foot intervals. Attributes for LABEL_10FT, LABEL_20FT, LABEL_50FT, LABEL_100FT were populated through calculations. Attribute QUAD_NO was populated by assigning the number of the USGS quadrangle that the contours are located within.

The horizontal positional accuracy of this data is not known. This data underwent automated processes to interpolate and create 2 foot elevation contours from the 20-foot posting LiDAR 2000 point data. The horizontal positional accuracy of the  20-foot posting LiDAR 2000 point data is approximately 3 feet on the ground. The data is not consistently accurate statewide. In some areas there are anomalies with the contour line information areas due to data gaps in the underlying LiDAR data used to generate the contour lines. This is a known limitation of the LiDAR data collected for Connecticut in 2000. Areas where the contours are incorrect are typically easy to recognize because, in relation to nearby contours, they appear too straight and angular, do not naturally curve as expected, or don't exist where they probably should. Also, contour lines may not conform very well to the shoreline of waterbodies and in many instances erroneously extend into areas of water. Due to the anomalies in the data, use caution when viewing and analyzing this information.

The data is not consistently accurate statewide. In some areas there are anomalies with the contour line information areas due to data gaps in the underlying LiDAR data used to generate the contour lines. This is a known limitation of the LiDAR data collected for Connecticut in 2000. Areas where the contours are incorrect are typically easy to recognize because, in relation to nearby contours, they appear too straight and angular, do not naturally curve as expected, or don't exist where they probably should. Also, contour lines may not conform very well to the shoreline of waterbodies and in many instances erroneously extend into areas of water. Due to the anomalies in the data, use caution when viewing and analyzing this information.

Connecticut 20 FT Contours

Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata.

Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.

None. No restrictions or legal prerequisites for accessing the metadata.

None. No restrictions or legal prerequisites for using the metadata after access is granted.