State of Connecticut, Department of Environmental Protection (editor and publisher) University of Connecticut, College of Agriculture and Natural Resources (compiler and editor) State of Connecticut, Department of Public Safety State of Connecticut, Department of Transportation Connecticut Joint Highway Research Council 20110502 vector digital data Hartford, Connecticut, USA State of Connecticut, Department of Environmental Protection http://www.ct.gov/deep Connecticut 10 ft Contours (Revised) is line feature-based data representing ground elevation at 10 foot intervals for the state of Connecticut. This data replaces the 10 ft contour data previously available from CT DEP. It has fewer errors and data gaps than the previously available contours; however, some inaccuracies remain. These contour lines have been processed to appear smoother and less jagged than the previous data and have been optimized for faster drawing and performance. The source for these data is the Connecticut LiDAR 10-foot DEM (file name: ct_lidar) from the Center for Land Use Education and Research at the University of Connecticut, College of Agriculture and Natural Resources. Connecticut 10 ft Contours (Revised) is used to depict ground elevation at 10 foot 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. 2000 ground condition Complete None planned -73.742650 -71.780655 42.053150 40.980191 none LiDAR contours ISO 19115 Topic Cateogry elevation environment U.S. Department of Commerce, 1987, Codes for the Identification of the States, the District of Columbia and the Outlying Areas of The United States, and Associated Areas (Federal Information Processing Standard 5-2): Washington, DC, National Institute of Standards and Technology. Connecticut CT U.S. Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions (Federal Information Processing Standard (FIPS) 10-4): Washington, D.C., National Institute of Standards and Technology. United States of America USA None. No restrictions or legal prerequisites for accessing the data. The data is in the public domain and may be redistributed. The data is suitable for use at appropriate scale; however, these data are not consistently accurate statewide. Users should review the following description of source data and process steps in order to determine the appropriate uses of this information. The original data source was 20-foot posting LiDAR point data collected in 2000, which has a horizontal positional accuracy of approximately 3 feet on the ground. The LiDAR point data has known limitations including data gaps. While the contour lines previously available from CT DEP were derived directly from the LiDAR point data, these contour lines were derived from the Connecticut LiDAR 10-foot DEM (file name: ct_lidar) from the Center for Land Use Education and Research (CLEAR) at the University of Connecticut, College of Agriculture and Natural Resources. During the production of the Connecticut LiDAR 10-foot DEM, CLEAR manually edited the data to fill in data gaps with coarser data based on contour lines from USGS topographic maps. Therefore, these contour lines contain fewer errors than the previously available contour lines. In order to produce less jagged contour lines, a circular averaging filter with a radius of 3 cells was applied to the Connecticut LiDAR 10-foot DEM (file name: ct_lidar). The contour lines were produced from this smoothed DEM. Visual inspection has shown that the resulting contour lines align well with the contour lines previously available from CT DEP. These contour lines, while less error-prone than the previous data, retain some errors from the LiDAR point data and may have other errors introduced during the editing and processing steps. Contour lines may not conform well to the shoreline of waterbodies and in many instances erroneously extend into areas of water. Due to these anomalies, use caution when viewing and analyzing this information. There are no restrictions or legal prerequisites for using the data after access is granted. 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 Conneticut, 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 these 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. State of Connecticut, Department of Environmental Protection Howie Sternberg mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time http://cteco.uconn.edu/metadata/dep/browsegraphic/contoursfullview100ft.gif Full view of the 100 ft contours. This image is included to show the coverage area of the 10 ft contours, which is the same area as for the 100 ft contours. GIF http://cteco.uconn.edu/metadata/dep/browsegraphic/contoursdetailview10and20ft.gif Detail view of the 10 and 20 ft contours. GIF http://cteco.uconn.edu/metadata/dep/browsegraphic/contoursdatagapbefore.gif A data gap in the contour lines previously available from DEP GIF http://cteco.uconn.edu/metadata/dep/browsegraphic/contoursdatagapafter.gif The revised contour lines, in the same area where there was previously a data gap GIF 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. The University of Connecticut, College of Agriculture and Natural Resources subsequently created and made accessible a variety of LiDAR-derived datasets. One of these, the Connecticut LiDAR 10-foot DEM (file name: ct_lidar), was used to create the smoothed statewide DEM from which this revised contour line feature class was created. None None No restrictions for handling the data Microsoft Windows 2000 Version 5.2 (Build 3790) Service Pack 2; ESRI ArcCatalog 9.2.6.1500 Connecticut 10 ft Contours (Revised) retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and derived from the Connecticut LiDAR 10-foot DEM. All attributes have valid values. Values are within defined domains. ELEV_FT attribute values are derived from the Connecticut LiDAR Smoothed DEM. Attribute INT_FT was populated through successive selections of ELEV_FT values based on calculations to select values for 10, 20, 50, and 100 foot intervals. Attributes for LABEL_10, LABEL_20, LABEL_50, and LABEL_100 were populated through calculations. Attributes QUAD_NO and QUAD_NAME were populated by assigning the number and name of the USGS quadrangle that the contours are located within. 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 content of the data sources, which consists of the Connecticut LiDAR 10-foot DEM (file name: ct_lidar) and its sources, the LiDAR 2000 elevation points and USGS topograhic maps. This data contains automatically generated contour lines that may contain errors or inconsistencies inherent in the automated process. The data also contains errors or inconsistencies related to errors inherent in the original LiDAR elevation data capture. There are no plans to update or correct these data. The horizontal positional accuracy of this data is not known. Users should review the following description of source data and process steps in order to determine the appropriate uses of this information. The original data source was 20-foot posting LiDAR point data collected in 2000, which has a horizontal positional accuracy of approximately 3 feet on the ground. The LiDAR point data has known limitations including data gaps. While the contour lines previously available from CT DEP were derived directly from the LiDAR point data, these contour lines were derived from the Connecticut LiDAR 10-foot DEM (file name: ct_lidar) from the Center for Land Use Education and Research (CLEAR) at the University of Connecticut, College of Agriculture and Natural Resources. During the production of the Connecticut LiDAR 10-foot DEM, CLEAR manually edited the data to fill in data gaps with coarser data based on contour lines from USGS topographic maps. Therefore, these contour lines contain fewer errors than the previously available contour lines. In order to produce less jagged contour lines, a circular averaging filter with a radius of 3 cells was applied to the Connecticut LiDAR 10-foot DEM (file name: ct_lidar). The contour lines were produced from this smoothed DEM. Visual inspection has shown that the resulting contour lines align well with the contour lines previously available from CT DEP. These contour lines, while less error-prone than the previous data, retain some errors from the LiDAR point data and may have other errors introduced during the editing and processing steps. Contour lines may not conform well to the shoreline of waterbodies and in many instances erroneously extend into areas of water. Due to these anomalies, use caution when viewing and analyzing this information. The data is not consistently accurate statewide. These contour lines, while less error-prone than the previous data, retain some errors from the LiDAR point data and may have other errors introduced during the editing and processing steps. Contour lines may not conform well to the shoreline of waterbodies and in many instances erroneously extend into areas of water. Due to these anomalies, use caution when viewing and analyzing this information. University of Connecticut, College of Agriculture and Natural Resources Unknown Storrs, Connecticut, USA University of Connecticut, Center for Land Use Education and Research (CLEAR) http://clear.uconn.edu disc 2000 ground condition 10-foot DEM This statewide digital elevation model (DEM) was generated by the Center for Land Use Education and Research (CLEAR), University of Connecticut using the 2000 Connecticut LiDAR point dataset, which consists of bare-earth x, y, and z point data derived from an Airborne LIDAR Topographic Mapping System (ALTMS). The x, y, and z values are stored in space-delimited ASCII files. These LiDAR elevation data are at a nominal 20-foot posting. To improve the DEM, CLEAR manually edited the 2000 Connecticut LiDAR point dataset to erase erroneous data and fill in data gaps with added points derived from contour lines that appear on USGS 1:24,000-scale Digital Raster Graphics (DRGs). State of Connecticut, Department of Environmental Protection 1985 2005 Hartford, Connecticut, USA State of Connecticut, Department of Environmental Protection http://www.ct.gov/deep 24000 disc 2005 publication date USGS Quad Index This data source contains the USGS quadrangles that cover the state of Connecticut. It was used to divide the contour lines into more evenly distributed shape lengths and to add attribute information. State of Connecticut, Department of Environmental Protection Unpublished Material computer program 2000 ground condition Smoothed DEM This data source is a smoothed version of the Connecticut LiDAR 10-foot DEM. The smoothing was performed using the ArcGIS Spatial Analyst extension to calculate a focal mean using a circular neighborhood with a radius of 3 cells. U.S. Geological Survey, National Mapping Program 1999 Hartford, Connecticut, USA State of Connecticut, Department of Environmental Protection http://www.ct.gov/deep 24000 disc 1999 publication date Waterbodies The Connecticut Waterbody Polygon layer was used to sytematically select and remove contour lines that were contained completely within waterbody polygons. Pre-processing the DEM: The Connecticut LiDAR 10-foot DEM was smoothed using the focal statistics tool in the ArcGIS Spatial Analyst extension. A circular neighborhood with a radius of 3 cells was used, and the statistic calculated was the mean. 10-foot DEM 20110401 Smoothed DEM State of Connecticut, Department of Environmental Protection Courtney Larson mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time Generate contours: The ArcGIS 3D Analyst extension was used to create two contour feature classes from the smoothed DEM at 20-foot intervals, using a different base contour value for each. The base contour values were 0 and 10. The first feature class has a base contour value of 0 and contains the contour values 20, 40, 60, etc; the second feature class has a base contour value of 10 and contains contour values 10, 30, 50, etc. The process was done in this way after attempts to produce 10 foot contours for the entire state failed because there was insufficient processing capacity to generate them all at once. Smoothed DEM 20110401 Two 20-ft contour layers State of Connecticut, Department of Environmental Protection Courtney Larson mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time Optimize contours: The line features were simplified by removing redundant vertices using the Simplify Line tool in ArcGIS. For the 10 foot contours, the maximum allowable offset was set to 3 feet. In testing, this offset value improved the performance of the feature class without making a significant visual difference when viewed at an appropriate scale. Two 20-ft contour layers 20110401 Two 20-ft contour layers State of Connecticut, Department of Environmental Protection Courtney Larson mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time Clean up records: Self-intersecting line features with a shape length of less than 50 feet were sytematically selected and removed. These features were circular contours so small they appeared almost as points when viewed at an appropriate scale. Therefore, they were determined to be too small to provide meaningful information. Subsequently, features that were completely within a waterbody polygon were sytematically selected and removed. Two 20-ft contour layers 20110401 Two 20-ft contour layers State of Connecticut, Department of Environmental Protection Courtney Larson mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time Edit attributes: The ArcGIS Identity tool was used to add USGS quadrangle attributes and to break up features into more uniform lengths for drawing and labeling performance purposes. The ID attribute was removed as it did not contain meaningful information. The Contour field was renamed ELEV_FT. The INT_FT attribute was added to classify the contour lines with elevation value ranges useful for symbolizing or selection of features. Label fields were added to assist with labeling at different intervals. Two 20-ft contour layers 20110401 Two 20-ft contour layers State of Connecticut, Department of Environmental Protection Courtney Larson 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time Merge contours: the two 20-ft contour layers (with base contour values of 0 and 10) were merged together to create a statewide 10 foot contour layer. Two 20-ft contour layers 20110401 Connecticut 10 Foot Contours (Revised) Vector String 331553 Lambert Conformal ConicLambert Conformal Conic41.20000041.866667-72.75000040.833333999999.999996499999.999998 coordinate pair 0.000328 0.000328 survey feet North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 North American Vertical Datum of 1988 1.000000 feet Explicit elevation coordinate included with horizontal coordinates Connecticut 10 ft Contours (Revised) 10 ft ground elevation contours represented as line features State of Connecticut, Department of Environmental Protection OBJECTID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. ELEV_FT Elevation of contour feature in feet Terrapoint LLC / University of Connecticut, College of Agriculture and Natural Resources 10 2410 INT_FT The contour line interval in feet. This is based on the value of ELEV_FT. These values are used for querying subsets and classifying features for symbology purposes. State of Connecticut, Department of Environmental Protection 10 10 foot contour interval 20 20 foot contour interval 50 50 foot contour interval 100 100 foot contour interval LABEL_10 10 foot contour label field. Used to label all contour lines with an elevation value evenly divisible by 10. State of Connecticut, Department of Environmental Protection 10 2410 LABEL_20 20 foot contour label field. Used to label all contour lines with an elevation value evenly divisible by 20. State of Connecticut, Department of Environmental Protection 20 2400 LABEL_50 50 foot contour label field. Used to label all contour lines with an elevation value evenly divisible by 50. State of Connecticut, Department of Environmental Protection 50 2400 LABEL_100 100 foot contour label field. Used to label all contour lines with an elevation value evenly divisible by 100. State of Connecticut, Department of Environmental Protection 100 2400 QUAD_NAME Name assigned to USGS quadrangles that cover Connecticut. State of Connecticut, Department of Environmental Protection USGS-assigned name SHAPE Feature geometry. ESRI Coordinates defining the features. QUAD_NO Number assigned to USGS quadrangles that cover Connecticut State of Connecticut, Department of Environmental Protection Integer SHAPE.len Includes 10 foot ground elevation contour line features. Information encoded about these features includes an ELEV_FT attribute and attributes for selection and cartographic symbology classification. Use the INT_FT attribute to select and symbolize features on a map. Use the LABEL_10, LABEL_20, LABEL_50, and LABEL_100 attribute fields to label elevation values on a map. State of Connecticut, Department of Environmental Protection mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time Connecticut 10 ft Contours (Revised) 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. File Geodatabase ArcGIS 10 no compression applied http://www.ct.gov/deep A copy of the data may be accessed without charge 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. Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information. 20111207 State of Connecticut, Department of Environmental Protection Courtney Larson mailing and physical address

79 Elm Street

Hartford CT 06106-5127 USA 860-424-3540 860-424-4058 dep.gisdata@ct.gov Monday to Friday, 08:30 to 16:30 Eastern Standard Time FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time None. No restrictions or legal prerequisites for accessing the metadata. None. No restrictions or legal prerequisites for using the metadata after access is granted. None None No restrictions for handling the metadata. http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile