New York State 2000 Digitally Enhanced OrthoImagery
NYS Department of State, Division of Coastal Resources, GIS Unit (Tom Hart, Jeff Herter, Peter Berical, Helen Chase, Julie Coman, Chih-Chung Kao, Matt Kohberger, Peter Lauridsen, Nikifor Nikiforov)
- Publication_Date: 199912
- Title: New York State 2000 Digitally Enhanced OrthoImagery
- Geospatial_Data_Presentation_Form: remote-sensing image
- Publication_Place: Albany, NY
NYS Department of State, Division of Coastal Resources, GIS Unit
- Online_Linkage: <http://www.dos.state.ny.us/>
Data set contains reprocessed digital orthophotography based on Digital Ortho Quarter Quads (DOQQ) derived from the National Aerial Photography Program
(NAPP). The original DOQQs were completed under the federal DOQQ program with state representation by NYS DEC.
A digital orthophoto is a raster image of remotely sensed data in which displacement in the image due to sensor orientation and terrain relief have been removed. Digital orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. The digital orthophotos in this series have a 1 meter pixel ground resolution.
The data set presents information that represents current conditions for New York State from 1994 - 1998. The coverage includes New York State and extends to parts of New Jersey, Pennsylvania, Vermont, and Canada. Areas not in the coverage are listed in the Completeness report.
The Digital Orthoimagery was reprocessed by New York State, Department of State, as part of the New York State Y2K Emergency Preparedness Plan. The orthoimagery was radiometrically balanced (enhanced) to reduce the variability between the DOQQs characteristic of the DOQQ product, and also to improve the feature visibility within individual images. The image format was also changed to geotiff, and then to MrSID formats in a tiled grid structure based on UTM axes. This was done to facilitate internet delivery of the orthoimagery The orthoimagery could serve a variety of purposes, from field references for spatial anaylsis to a tool for revision of vector based maps. The orthoimagery can also be useful as a layer for a GIS or as an interim map.
Bounding coordinates for individual sixteenth tiles can be found at <http://www.nysgis.state.ny.us/gis/gateway/coordinates_sample.html> Scale: 1:12,000 scale
- Beginning_Date: 1994
- Ending_Date: 1998
- Currentness_Reference: ground condition
- Progress: Complete
- Maintenance_and_Update_Frequency: As needed
- West_Bounding_Coordinate: -79.75
- East_Bounding_Coordinate: -71.75
- North_Bounding_Coordinate: 45
- South_Bounding_Coordinate: 40.5
- Theme_Keyword_Thesaurus: NYS GIS Clearinghouse categories
- Theme_Keyword: land use or land cover
- Theme_Keyword_Thesaurus: None
- Theme_Keyword: Digital Orthophotography
- Place_Keyword_Thesaurus: None
- Place_Keyword: New York
- Browse_Graphic_File_Name: <http://www.nysgis.state.ny.us/gis/gateway/sample_image_albany.html>
- Browse_Graphic_File_Description: Albany, New York
- Browse_Graphic_File_Type: JPEG
The data set was created in the Windows NT operating system. The software programs used to enhance digital orthophotos were PCI EASI/PACE and ImageWorks, MapInfo, Adobe Photoshop, and MrSID.
[The data set is raster based and was not digitized. Thus, the logical consistency report is not applicable to the imagery since any varying resolution would be trivial.]
File naming was adapted from New York State Department of Transportation (NYSDOT) Quad names. USGS Quad names were used if a NYSDOT Quad did not exist because the area is outside of New York State. A file naming convention was established for these quads using an " _OE" extension after the quad name.
All files were inspected by Department of Transportation staff to provide an independent assessment of consistency in file naming, relative accuracy in comparison to existing state data, image appearance, and completeness of the data set. The current data set includes corrections made based on this independent process.
A small number of tiles were unavailable in the original DOQQ format, these images were extracted from SID (compressed) files obtained from the NYS Department of Environmental Conservation. These images were exported to tiff files for rebalancing, then compressed. This process led to a slight discoloration, and some image degradation to the imagery due to the lossy nature of the SID compression routine.
Imagery is included for all land cover which falls within New York State county boundaries, with the exception of 95 Quads, and 16 Quarter Quads where orthoimagery is unavailable for New York State.
<http://www.nysgis.state.ny.us/gis/gateway/Imagery_Unavailable.html> Excluded areas were flown in Spring 1999.
- Horizontal_Positional_Accuracy_Value: 10.06 m
The entire New York State Digital Ortho Quarterquad (DOQQ) imagery data set has been reprocessed to address file size and format issues, and to address extreme variation in the visual quality of the orthoimagery. New York State Department of State (NYSDOS), Coastal Resources Division, GIS Unit reprocessed the data to reduce radiometric variability. Original data was obtained from the United States Department of Agriculture, Natural Resource Conservation Service (NRCS) in Syracuse, New York. Some data unavailable from the NRCS was also provided by New York State Department of Environmental Conservation, Albany, New York.
Orthoimagery was first converted from DOQQ format (bip format - band interleaved by pixel or key format) into geotiff format using raster processing GIS software (PCI ImageWorks). Each quarter quad was subset into four tiles to facilitate ease of file processing and to allow for a seamless tile design based on a UTM grid (sixteenth tile format). The subset tiles were used as the base data for image enhancement. Tiles were slightly staggered to compensate for offsets associated with the progression of Latitude/Longitude grids relative to UTM grids. The DOQQs were reprojected from UTM Zones 17 and 19 into an extended UTM Zone 18 to match statewide vector data compilations. Images reprojected into UTM Zone 18 required resampling, which was accomplished using cubic convolution to preserve the original spectral content to the greatest extent.
Two methods were employed for radiometric balancing: 1) Custom balancing (enhancement) of individual tiles and 2) Use of an automated batch process. Individual tiles were radiometrically corrected using operator-defined enhancements. Corrections were made using image editing software (Adobe Photoshop) which allowed for simultaneous observation of the image and the image band histograms. The image's quality was adjusted for brightness, contrast, color balance, and low, midpoint, and high stretch values along with other custom adjustments as needed. Image balancing was biased towards a real world presentation, which while retaining infra-red data, provided a user-friendly appearance. Throughout the process, particular care was taken to avoid data loss, especially through clustering pixel values at the image histogram minima and maxima values (0, 255). Areas of common features such as water and upland cover types were also masked and adjusted independent of the remaining image content when required. A number of areas required rebalancing using this operator intensive method entirely.
The majority of the rebalancing was accomplished using an automated batch process. The individual tile method was used for the creation of reference imagery tiles. The standards for the reference imagery tiles, representing the highest spectral and image quality for specific image content types such as urban areas, forested land, and agricultural land, were agreed upon by the NYSDOS GIS Project Team.
The majority of the image rebalancing task was accomplished by using these reference tiles to model image adjustment for large groups of raw imagery files. The reference tile was used to automatically adjust batches of tiles with similar image content. These adjustments were made using raster processing GIS software (PCI Works) which allowed for the creation of individual look-up table overlays representing a pixel and band specific mathematical conversion model for each tile. Once the image adjustment batch was completed, resulting tiles were inspected for image quality and those deviating from the original reference were individually retouched using Adobe Photoshop. Those tiles most frequently needing additional operator attention tended to be images containing a mix of land and water features.
Acceptable image tiles were saved in geotiff format. These final product images were prepared for end user applications using wavelet compression software (MrSID) compressed at 1:20 ratio to create image files in the 1.2 to 1.4 Mb file size to facilitate ease of use and internet delivery potential. A comprehensive grid data set was created including image file names, associated quarter quad name, and other relevant geographic data to allow users a reference and a means of access to individual tiles. GIS software-controlled mosaic files were also created: seamless tables for MapInfo and image catalogs for ESRI users.
- Process_Date: 199908
- Direct_Spatial_Reference_Method: Raster
- Grid_Coordinate_System_Name: Universal Transverse Mercator
- UTM_Zone_Number: 18
- Scale_Factor_at_Central_Meridian: .9996
- Longitude_of_Central_Meridian: -75.0
- Latitude_of_Projection_Origin: 0.0
- False_Easting: 500000.0
- False_Northing: 0.0
- Planar_Coordinate_Encoding_Method: coordinate pair
- Abscissa_Resolution: .61
- Ordinate_Resolution: .61
- Planar_Distance_Units: meters
- Horizontal_Datum_Name: North American Datum of 1983
- Ellipsoid_Name: Geodetic Reference System of 1980
- Semi-major_Axis: 6378137
- Denominator_of_Flattening_Ratio: 298.257222101
- Contact_Organization: NYS GIS Clearinghouse (via internet)
- Contact_Position: Sharon Oskam
- Address_Type: mailing and physical address
Cultural Education Center, Empire State Plaza, New York State Library
- City: Albany
- State_or_Province: NY
- Postal_Code: 12203
- Country: USA
- Contact_Voice_Telephone: 518-474-6280
- Contact_Facsimile_Telephone: 518-474-5786
- Contact_Electronic_Mail_Address: email@example.com
- Resource_Description: New York State 2000 Digitally Enhanced OrthoImagery
- Metadata_Date: 20000411
- Contact_Person: Thomas Hart
- Address_Type: mailing and physical address
- Address: 41 State Street
- City: Albany
- State_or_Province: NY
- Postal_Code: 12231
- Country: USA
- Contact_Voice_Telephone: 473-2465
- Contact_Electronic_Mail_Address: firstname.lastname@example.org
- Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
- Metadata_Standard_Version: FGDC-STD-001-1998
Generated by mp version 2.2.3 on Thu May 4 14:50:45 2000