This data set is a statewide raster mosaic of 2008, 4 band natural color and color infrared, 1 meter ground sample distance imagery for Connecticut from the National Agriculture Imagery Program (NAIP). NAIP acquires digital ortho imagery during the agricultural growing seasons in the continental U.S.. A primary goal of the NAIP program is to enable availability of ortho imagery within one year of acquisition. NAIP provides four main products: 1 meter ground sample distance (GSD) ortho imagery rectified to a horizontal accuracy of within +/- 5 meters of reference digital ortho quarter quads (DOQQ's) from the National Digital Ortho Program (NDOP); 2 meter GSD ortho imagery rectified to within +/- 10 meters of reference DOQQs; 1 meter GSD ortho imagery rectified to within +/- 6 meters to true ground; and, 2 meter GSD ortho imagery rectified to within +/- 10 meters to true ground. The tiling format of NAIP imagery is based on a 3.75' x 3.75' quarter quadrangle with a 300 meter buffer on all four sides. NAIP quarter quads are formatted to the UTM coordinate system using NAD83. NAIP imagery may contain as much as 10% cloud cover per tile.
NAIP imagery is available for distribution within 60 days of the end of a flying season and is intended to provide current information of agricultural conditions in support of USDA farm programs. For USDA Farm Service Agency, the 1 meter GSD product provides an ortho image base for Common Land Unit boundaries and other data sets. The 1 meter NAIP imagery is generally acquired in projects covering full states in cooperation with state government and other federal agencies who use the imagery for a variety of purposes including land use planning and natural resource assessment. With an annual cycle, NAIP is also used for disaster response often providing the most current pre-event imagery. While suitable for a variety of uses the 2 meter GSD NAIP imagery is primarily intended to assess crop condition and compliance to USDA farm program conditions. The 2 meter imagery is generally acquired only for agricultural areas within state projects.
This statewide raster mosaic was prepared by the State of Connecticut, Department of Environmental Protection (CT DEP) using 2008, 4 color band, 1 meter ground sample distance imagery (input rasters) from the USDA-FSA-APFO Aerial Photography Field Office. These original input rasters are in GeoTIFF format and because there are two UTM Zones in Connecticut, the input rasters are in either the NAD 1983 UTM Zone 18N Meters or NAD 1983 UTM Zone 19N Meters. The individual rasters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet and merged together in the resulting statewide mosaic. Using ESRI ArcGIS 9.2 software, statistics for the pixel color values in the image have been calculated and stored with the imagery data. This has been done to improve drawing performance and to easily manage how color bands are displayed. Depending on the GIS software used to view the image, the creation of these statistics may result in a default display of the raster mosaic in extreme colors values rather than in a natural color scheme. However, this can be changed with most software. For example, when viewing the imagery with ESRI ArcMap software, change the Symbology Stretch setting from a value of Standard Deviation to None to achieve a more natural range of colors for both color and color infrared displays. Apply these band settings to obtain full color imagery. Red = Band 1 Green = Band 2 Blue = Band 3 Apply these band settings to obtain color infrared imagery. Red = Band 4 Green = Band 1 Blue = Band 2
ground condition
Imagery may be replaced to address defects found in a small number of products through quality assurance processes. Imagery containing defects that require the acquisition of new imagery, such as excessive cloud cover, specular reflectance, etc., will not be replaced within a NAIP project year.
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NAIP 3.75 minute tile file names are based on the USGS quadrangle naming convention.
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FSA Digital Orthophoto Specs.
Digital Georectifed Image (2006 NAIP 1 meter DOQQ). Each image is in GeoTIFF format. Depending in the location, NAIP quarter quads are either in NAD 1983 UTM Zone 18N or NAD 1983 UTM Zone 19N coordinate system. UTM Zones 18N and 19N encompass portions of Connecticut. NAIP DOQQ (3.75 minute tile) file names are based on the USGS quadrangle naming convention.
Statewide raster mosaic of all NAIP DOQQ input rasters. The raster mosaic is in the Connecticut State Plane Coordinate System, North American Datum of 1983 (NAD83).
The imagery was collected at a flying height of 21000 ft above mean terrain with 25% sidelap using an ADS40 digital sensor, giving the collected data nominal ground sampling distance of 0.7 meters. Collected data was downloaded to portable hard drives and shipped to the processing facility daily. Airborne GPS / IMU data was processed and reviewed to ensure sufficient accuracy for project requirements. Planar rectified images were generated from the collected data for use in image quality review. The planar rectified images were generated at five meter resolution using a two standard deviation histogram stretch. Factors considered during this review included but were not limited to the presence of smoke and/or cloud cover, contrails, light conditions and sun glint. When necessary, image strips identified as not meeting image quality specifications were re-flown to obtain suitable imagery.
Aerotriangulation blocks were defined primarily by order of acquisition and consisted of two to twelve strips. Image tie points points providing the observations for the least squares bundle adjustment were selected from the images using an autocorrelation algorithm. Photogrammetric control points consisted of photo identifiable points selected from base imagery provided by USDA FSA APFO. Elevations for the control points were sampled from USGS NED DEMs. The control points were loaded in to a softcopy workstation and measured in the acquired image strips. A least squares bundle adjustment of image pass points, control points and the ABGPS was performed to develop an aerotriangulation solution for each block. Precedence was given to the photo identifiable control points over control provided by the ABGPS solution in the bundle adjustment to ensure the final solution would agree with the provided base imagery within the required tolerances.
The triangulated strips were ortho-rectified to the USGS NED DEM for the project area. The images were re-sampled from the raw resolution of 0.7 meters to the required resolution of 1.0 meters using a cubic convolution filter during the process. The red, green, blue, and NIR bands were combined to generate a final ortho-rectified image strip. The ADS40 sensor collects twelve bit image data which requires radiometric adjustment for output in standard eight bit image channels. The ortho-rectified image strips were produced with the full 12 bit data range, allowing radiometric adjustment to 8 bit range to be performed on a strip by strip basis during the final mosaicing steps.
The imagery was mosaicked using a combination of automated and manual seamline generation. The 12 bit data range was adjusted for display in standard eight bit image channels by defining a piecewise histogram stretch. A constant stretch was defined for each image collection period, and then strip by strip adjustments were made as needed to account for changes in sun angle and azimuth during the collection period. Strip adjustments were also made to match the strips histograms as closely as possible to APFO specified histogram metrics and color balance requirements. Automated balancing algorithms were applied to account for bi-directional reflectance as a final step before the conversion to 8 bit data range. APFO specified DOQQs were extracted from the final mosaic in GeoTIFF format.
Each DOQQ clipped from the mosaic was reviewed for conformance to APFO histogram metrics and color balance parameters using automated procedures. Images flagged for non-conformance were reviewed and adjusted manually on an image by image basis to bring them into conformance. In extreme cases, such as when a DOQQ was comprised primarily of water, modification of the histogram metrics to match targets caused severe degradation of image quality. In these cases, the water was masked out and histogram adjustments were applied to land. GeoTIFF tags for the appropriate UTM zone were then applied to all images
Using ESRI ArcGIS 9.2 software, an empty raster dataset was created and subequently populated with input rasters to create a statewide raster mosaic. The State of Connecticut, Department of Environmental Protection obtained these input rasters from the USDA-FSA-APFO Aerial Photography Field Office, 2222 West 2300 South, Salt Lake City, 84119-2020. 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 90. The Pyramid Reference Point X and Y coordinate are 687800 and 1015180, respectively. Bands: 4. Pyramids: 12 Bilinear. The Pixel Type is 8_BIT_UNSIGNED, which supports index values from 0 to 255. Raster statistics were built for all 4 bands. Below is a record of the ESRI Geoprocessing CreateRasterDataset command and arguments that created the empty raster dataset. CreateRasterDataset "Database Connections\10.18.8.60.depgis@dep_92dc.sde" ORTHO_2008_4BAND_NAIP # 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]] 4 DEPRASTER "PYRAMIDS 12 BILINEAR" "128 128" "JPEG 90" "687800 1015180" "Database Connections\10.18.8.60.depgis@dep_92dc.sde\depgis.DEP.ORTHO_2008_4BAND_NAIP" STEP 2 - Mosaic 412 quarter quadrangle input rasters that cover Connecticut. 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 and NAD 1983 UTM Zone 19N Meters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet. Below is an example usage of the ESRI Geoprocessing Mosaic command and arguments used to mosaic 4 (quarter quadrangle) input rasters in TIFF format. Mosaic Y:\tif_format_utm19\42071\m_4207157_se_19_1_20080716.tif; Y:\tif_format_utm19\42071\m_4207157_sw_19_1_20080716.tif; Y:\tif_format_utm19\42071\m_4207158_se_19_1_20080716.tif; Y:\tif_format_utm19\42071\m_4207158_sw_19_1_20080716.tif "Database Connections\10.18.8.60.depgis@dep_92dc.sde\DEPGIS.DEP.ORTHO_2008_4BAND_NAIP" LAST FIRST 1 # NONE 0 "Database Connections\10.18.8.60.depgis@dep_92dc.sde\DEPGIS.DEP.ORTHO_2008_4BAND_NAIP" STEP 3 - Calculate Statistics. Using ESRI ArcGIS 9.2 software, statistics for the pixel color values in the image have been calculated and stored with the imagery data. This has been done to improve drawing performance and to easily manage how color bands are displayed. Depending on the GIS software used to view the image, the creation of these statistics may result in a default display of the raster mosaic in extreme colors values rather than in a natural color scheme, for example. However, this can be changed with most software. For example, when viewing the imagery with ESRI ArcMap software, change the Symbology Stretch setting from a value of Standard Deviation to None to achieve a more natural range of colors for both color and color infrared displays.
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The 20090730 edition of this raster mosaic corrects an error found with one quarter quadrangle input raster, 4107101_se_19_1_20080710.tif, which was improperly georeferenced. This process step involved using the ArcGIS 9.2 georeferencing tool to correctly geoference this input raster to UTM Zone 19. A total of four control points from two adjacent input rasters located to the west (4107101_sw_19_1_20080710.tif) and east (4107102_sw_19_1_20080710.tif) were used to re-georeference 4107101_se_19_1_20080710.tif. The corrected raster and the four surrounding input rasters (4107101_sw_19_1_20080710.tif, 4107101_ne_19_1_20080716.tif, 4107102_sw_19_1_20080710.tif, and 4107109_ne_19_1_20080710.tif) were later mosaiced and added to the statewide raster dataset. 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. As with the initial mosaic process, these input rasters in NAD 1983 UTM Zone 19N Meters were projected to NAD 1983 StatePlane Connecticut FIPS 0600 Feet.
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32-bit pixels, 4 band color(RGBIR) values 0 - 255
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In no event shall the creators, custodians, or distributors of this information be liable for any damages arising out of its use (or the inability to use it).
Multispectral 4-band
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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.
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.
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