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GIS.NY.GOV

NYS ITS GIS Program Office

Geographic Information Systems Clearinghouse

Frequently Asked Questions

General Help Using Digital Orthoimagery

Frequently Asked Questions:

Digital Orthoimagery Information
Coordinates
Projection
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Using Digital Orthoimagery

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General Help

Files to Download
File Format Table
File Format Description Open With
.sid Mr Sid format compressed image file MrSid Geoviewer, High-end image processing software, *MapInfo, *ArcView
.sdw world file - ascii file that contains real-world tranformation information for image ESRI software (ArcInfo, ArcView, ArcExplorer)
.jp2 JPEG 2000 compressed image file ExpressView, High-end image processing software, *MapInfo, *ArcView
.j2w world file - ascii file that contains real-world tranformation information for JPEG 2000 image ESRI software (ArcInfo, ArcView, ArcExplorer)
.tab MapInfo georegistration file type MapInfo, ProViewer
.aux is the auxillary files used with ESRI ArcGis ESRI software (ArcInfo, ArcView, ArcExplorer)
.zip An archive file that contains other files. Usually the files in the archive are compressed. Makes copying & moving files easier. WinZip, PKzip
00IC*.dbf An image catalog (ESRI software) - an organized collection of images that can be accessed as one logical image theme. ESRI software (ArcInfo, ArcView)
00ST_*.tab, 00ST_*.map, 00ST_*.id, 00ST_*.dat A seamless table is a group of base tables assembled as if they were one table. A seamless layer allows you to display an entire group of tables (images) at once. MapInfo software

For information on how to use these files refer to the "Viewing the Orthoimagery" section.

(* MapInfo and MapInfo ProViewer users need the *.sid and the *.tab file to view the orthoimagery. ArcView & ArcExplorer users need the *.sid and *.sdw to view the orthoimagery)

File Naming Convention

NYSDOP High Resolution Statewide Imagery

State Plane Coordinate Tiles
z_eeeennnn_pp_hhhhh_fff_yyyy.ext

Where:

  • "z" = State Plane Zone (e = East, c = Central, w = West, l = Long Island)
    The Easting and Northing coordinates are concatenated
  • "eeee" = Truncated Easting coordinate of southwest corner of the tile. The last three digits are dropped, since they will always be "000." Leading zeros are used where appropriate.
  • "nnnn" = Truncated Northing coordinate of the southwest corner of the tile. The last three digits are dropped, since they will always be "000." Leading zeros are used where appropriate.
  • "pp" = Image pixel size in inches
  • "hhhhh" = Flying height in feet
  • "fff" = Film or image type (pan = panchromatic, col = natural color,
    cir = color infrared
  • "yyyy" = Year of image capture
    Example of concatenation and truncation of coordinates

Example:
e_03451234_12_14400_cir_2001.ext

Zone = NY State Plane East Zone
Easting = 345,000 feet
Northing = 1,234,000 feet
Pixel size = 12 inches (1 foot)
Flying height = 14,400 feet
Film type = Color infrared
Year = 2001

NAPP 1 Meter Resolution Statewide Imagery

UTM Coordinate Tiles Quadname
Quarter_tile.extension

Where:

  • "Quadname" = Parent quadrangle name derived from the Dept. Of Transportaton (DOT) naming convention, including areas outside of New York if available. USGS names were used if a DOT name was not available
  • "Quarter" = The Quadrant of the Quadrangle relative to compass directions, ie NW, SE
  • "_tile" = The quarter section of the quarterquad, numbered beginning in the upper left section and proceeding clockwise

Example:
BrewsterNE_tile0.sid

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Viewing the Orthoimagery

There are several image viewing programs available to use for the purpose of viewing our orthoimagery. See our "Useful Software" page to link to free software available for download. Each of the software programs has help menus and documentation on their use.

In addition to viewing orthoimagery, popular GIS software programs can use the orthoimagery for general reference and orientation, feature identification, and the measurement of distance and area. The following are general tips to get started:

MapInfo Professional

ESRI - (ArcView, ArcInfo)

For additional information using and viewing digital orthoimagery, please go to the Introduction to Digital Orthoimagery on-line training presentation for reference.

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Orthoimagery Indexes

Each digital orthoimagery data set has a corresponding index to the tiles of orthoimagery. There may be more than one index if there are different film types and/or the orthoimagery in the application is available in more than one coordinate system. The indexes contain Information such as the tile name, the source date, and the x and y coordinates. The indexes can be viewed using GIS software.

NYSDOP High Resolution Imagery - Refer to the County Direct Download page for the individual county indexes.

NAPP 1 Meter Resolution Imagery - Refer to the NAPP Region Direct Download individual tile page for the indexes.

Attribute Dictionary for NYSDOP High Resolution Imagery and NAPP 1 Meter Resolution Imagery:

Tile_Name: The image registration file (MapInfo format used to dynamically access the imagery files).
*.sid (or *.jp2) The image size in kb
*.sdw (or *.j2w) The file size in kb
*.tab The file size in kb
*.aux The file size in kb

Useful Software

Listed below are links to "free" software to use to view or download the orthoimagery files.
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