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.

Aerial Photography Date for aerial photo source.

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).

Aerial Photography Date for aerial photo source.

The imagery was collected at a flying height of 28000 ft above mean terrain with 20% sidelap using an ADS40 digital sensor, giving the collected data nominal ground sampling distance of 0.9 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.  Aerotriangulation blocks were defined primarily by order of acquisition and consisted of one to ten strips.  Terrain points providing the observations for the least squares bundle adjustment were selected from the images using an autocorrelation algorithm.  Photogrammetric control 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 collected imagery.  A least squares bundle adjustment of terrain 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 0.9 meters to the required resolution of 1.0 meters using a cubic convolution filter during the process. The red, green and blue 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.  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.  Final DOQQs were reviewed for artifacts and anomalies and adjusted as part of quality control procedures. When necessary, local corrections to the imagery were performed to minimize the effects of such artifacts. 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 Tolland State Office of the NRCS at 344 Merrow Road, Suite A, Tolland, Connecticut  06084-3917.

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: 3. Pyramids: 8 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 "Database Connections\10.18.8.94.depgisraster@DEP_Direct.sde" Ortho_2006_Color_Load # 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 DEPRASTER "PYRAMIDS 8 BILINEAR" "128 128" "JPEG 90" "687800 1015180" "Database Connections\10.18.8.94.depgisraster@DEP_Direct.sde\depgisraster.DEP.Ortho_2006_Color"\

STEP 2 - Mosaic 410 of 411 quarter quadrangle input rasters that cover Connecticut. Due to poor image quality, one quarter quad, Amenia SE (n_4107312_se_18_1_20060731_20070319.tif), was not included in the statewide mosaic. 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 8 (quarter quadrangle) input rasters in TIFF format.

Mosaic D:\tif_fomat\42073\n_4207361_se_18_1_20060716_20070201.tif 
D:\tif_fomat\42073\n_4207361_sw_18_1_20060716_20070201.tif; D:\tif_fomat\42073\n_4207362_se_18_1_20060805_20070201.tif; D:\tif_fomat\42073\n_4207362_sw_18_1_20060805_20070201.tif; D:\tif_fomat\42073\n_4207363_se_18_1_20060814_20070201.tif; D:\tif_fomat\42073\n_4207363_sw_18_1_20060814_20070201.tif; D:\tif_fomat\42073\n_4207364_se_18_1_20060814_20070201.tif; D:\tif_fomat\42073\n_4207364_sw_18_1_20060814_20070201.tif "Database Connections\depdbs11.depgisraster@DEP.sde \DEPGISRASTER.DEP.ORTHO_2006_COLOR_LOAD"
LAST FIRST 1 # NONE 0
"Database Connections\depdbs11.depgisraster@DEP.sde \DEPGISRASTER.DEP.ORTHO_2006_COLOR_LOAD"