This is a raster mosaic of 2008, natural color, leaf off, 1 ft ground sample distance imagery from the U.S. Geological Survey for the Bridgeport, Hartford and New Haven, Connecticut Urban Areas. Imagery only exists for these three geographic regions. This task order consists of digital orthophoto production covering the CT Cities 133 Urban Area footprint. An orthoimage is remotely sensed image data in which displacement of features in the image caused by terrain relief and sensor orientation have been mathematically removed. Orthoimagery combines the image characteristics of a photograph with the geometric qualities of a map.
The raster mosaic of 2008 USGS Urban Area Orthoimagery was prepared by the State of Connecticut, Department of Environmental Protection (CT DEP) using data provided by the USGS. The original input rasters are in GeoTIFF format and in NAD 1983 UTM Zone 18N Meters. These data are also available online from USGS National Map Seamless Server. The individual rasters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet and merged together in the resulting mosaic for the Bridgeport, Hartford, and New Haven Connecticut Urban Areas. The data obtained through The National Map Seamless Server is considered to be the "best available" data from USGS. Historical data and other data may be obtained by contacting Customer Services, Earth Resources Observation and Science Center at 1-800-252-4547. Information in quotation marks, initial processing steps, accuracy reports, and source information is taken directly from the original metadata. Spatial-specific information not available
ground condition
Natural color orthoimagery is organized in three color bands or channels which represent the red, green, and blue portions of the spectrum. Each image pixel is assigned a triplet of numeric values, one for each color band. Numeric values range from 0 to 255. Areas where data is incomplete due to lack of full image coverage are represented with the numeric value of 0.
U.S. Department of the Interior, U.S. Geological Survey, 1999, Standards for Digital Orthoimagery: Reston, VA
U.S. Geological Survey and Aero-Metric, Inc.
USGS Earth Resources Observation and Science Center
47914 252nd Street
High Resolution Orthoimagery provides a critical tool for those involved in development decisions such as resource managers and city planners. The detailed focus of High Resolution Orthoimagery provides emergency responders critical information in determining the best evacuation routes, alternative routes and safe access to aid. High Resolution Orthoimagery assists law enforcement personnel in determining the best locations to place surveillance cameras in high-traffic urban areas and popular attractions. A digital orthoiamge is a geometrically accurate photographic record of landscape conditions at the time of the corresponding aerial photography. As such, the digital orthoimage is useful for a variety of applications, such as environmental monitoring, facility engineering/maintenance, city/county planning, property line review, etc. The digital orthoimage can be used alone or as a raster basemap for corresponding vector line mapping. The data assists Federal, State and local emergency responders in planning for homeland security efforts. This data also supports The National Map.
Source imagery for orthophoto production.
Used to provide ground elevations for orthorectification process.
Used to provide photo exterior orientations for orthorectification process.
Statewide mosaic of all Orthophoto TIFFS
The raw scanned photos were aerotriangulated to support digital ortho image production for the CT Cities project area. Airborne GPS and ground check point data was provided by AERO-METRIC, Inc. The project was referenced to the North American Datum of 1983 (NAD83), Universal Transverse Mercator, Zone 18 horizontally and to the North American Vertical Datum of 1988 (NAVD88) vertically. Units were in meters.The scanned images (14 micron), ABGPS data, ground check point data, and camera calibration data were used as inputs to the Zeiss/Intergraph ImageStation Automatic Triangulation (ISAT) softcopy program. ISAT correlated image points and aerotriangulated the block of images to create exposure station exterior orientations. All ground checkpoints were manually measured on the imagery. These ground checkpoints were included in the aerotriangulation adjustments as unconstrained points for absolute ground location verification.The scale of the aerial photos was 1:21,600. The photography was exposed on 4/2/08, 4/3/08 and 4/8/08.Rectification was done using the aerotriangulation data, scans, NED data. These rectified images were used to draw seamlines. The images were then dodged. The dodged rectified images were mosaicked, balanced, and cut into final image sheets. The final sheets were viewed and artifacts were removed as well as other edits performed.
The metadata were imported and updated for display through The National Map Seamless Server at http://seamless.usgs.gov Project level metadata are available in several formats: HTML, TEXT, XML, FAQ and SGML.
USGS Earth Resources Observation and Science Center
47914 252nd Street
The USGS point of contact is for questions relating only to the data display and download from this web site. For questions regarding data content and quality, refer to original processor.
Using ESRI ArcGIS 9.2 software, an empty raster dataset was created and subsequently populated with input rasters to create a statewide raster mosaic. The State of Connecticut, Department of Environmental Protection obtained these TIFF images from the U.S. Geological Survey. STEP 1 - Create Raster Dataset - The Coordinate System for the raster dataset is NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet. The image compression type is JPEG with a compression quality of 75. The Pyramid Reference Point X and Y coordinate are 687800 and 1015180, respectively. Bands: 3. Pyramids: 12 Bilinear. The Pixel Type is 8_BIT_UNSIGNED, which supports index values from 0 to 255. Raster statistics were not built. Below is a record of the ESRI Geoprocessing CreateRasterDataset command and arguments that created the empty raster dataset. CreateRasterDataset C:\CT\2008\Connecticut_Ortho_2008_Urban_Area.gdb Ortho_2008_Color_USGS_Urban_Area # 8_BIT_UNSIGNED PROJCS['NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet', GEOGCS['GCS_North_American_1983',\ DATUM['D_North_American_1983', SPHEROID['GRS_1980',6378137.0,298.257222101]], PRIMEM['Greenwich',0.0], UNIT['Degree',0.0174532925199433]], PROJECTION['Lambert_Conformal_Conic'], PARAMETER['False_Easting',999999.999996], PARAMETER['False_Northing',499999.999998], PARAMETER['Central_Meridian',-72.75], PARAMETER['Standard_Parallel_1',41.2], PARAMETER['Standard_Parallel_2',41.86666666666667], PARAMETER['Latitude_Of_Origin',40.83333333333334], UNIT['Foot_US',0.3048006096012192]] 3 # "PYRAMIDS 12 BILINEAR" "128 128" "JPEG 75" "687800 1015180" C:\CT\2008\Connecticut_Ortho_2008_Urban_Area.gdb\Ortho_2008_Color_USGS_Urban_Area STEP 2 - Mosaic input rasters for the Bridgeport, Hartford, and New Haven Urban Area. The Ignore Background Value was set to one (1). The NoData value was left blank. The Mosaicking Tolerance value was set to zero (0). Consequently, pixel values in the raster mosaic resulted from a resampling of pixels values from individual input rasters due to the difference in alignment of input and mosaic (target) pixels. Note, in the resulting mosaic, the input rasters in NAD 1983 UTM Zone 18N Meters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet.
79 Elm Street
Radiometry is verified by visual inspection of the digital orthophoto. Slight systematic radiometric differences may exist between adjacent orthoimage files; these are due primarily to differences in source image capture dates and sun angles along flight lines. These differences can be observed in an image's general lightness or darkness when it is compared to adjacent orthoimage file coverages. Tonal balancing may be performed over a group of images during the mosaicking process which may serve to lighten or darken adjacent images for better color tone matching.
The relative accuracy is assembled by comparing rectified images generated from adjacent strips of imagery. The absolute accuracy is assessed by measuring the ground control points in the rectified image against the actual surveyed co-ordinate position. The testing is for overall accuracy. This data has been produced to be fully compliant with the National Map Accuracy Standards (NMAS) for mapping at this scale.
There is no vertical accuracy component to orthophotography.
Orthoimages are visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images. These images are derived by mosaicking multiple images to ensure complete coverage. Source imagery is cloud free.
GeoTIFFs conform to the specifications set forth by the USGS for production of 133 UA orthophotos.
There is no guarantee of warranty concerning the accuracy of the data. Users should be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. Acknowledgement of the originating agencies would be appreciated in products derived from these data. Any user who modifies the data is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Please refer to http://www.usgs.gov/privacy.html for the USGS disclaimer.
Earth Resources Observation and Science Center
47914 252nd Street
The USGS point of contact is for questions relating only to the data display and download from this web site. For questions regarding data content and quality, refer to the original processor.
Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. Data may have been compiled from various outside sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.
| Data format: | Natural Color in format TIFF (version ArcGIS 9.3) Raster Size: 0.001 |
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| Network links: | http://seamless.usgs.gov |
| Media you can order: | CD-ROM(format ISO 9660 Mode 1 Level 2 Extensions) |
79 Elm Street
Although these data have been used by the State of Connecticut, no warranty, expressed or implied, is made by the State of Connecticut as to the accuracy of these 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 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.
| Data format: | in format Raster Dataset (version ArcGIS) |
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| Network links: | http://www.ct.gov/deep |
| Media you can order: | disk |
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.
USGS Earth Resources Observation and Science Center
47914 252nd Street
The above is the contact information for the Earth Resources Observation and Science Center in Sioux Falls, SD. This is the digital data storage and distribution center for the USGS.