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1998/1999 Illinois DOQQs
1 Meter Black and White
MrSid Compressed
General Information about the Illinois DOQQs:
- USGSNAME
Codified USGS name. Files are stored with the USGS file naming conventions. The USGS subdivides data by 1 x 1 degree tile based on the coordinates of the
southeast corner. Each 1 x 1 degree tile contains:
- one-half of a 1 x 2 degree quadrangle
- two 30 x 60 minute quadrangles
- 64 7.5' quadrangles in an 8 x 8 grid
- 256 quarter-quadrangles (scale of DOQ imagery)
There are 27 1 x 1 degree tiles that intersect Illinois.
Here is the general form for path and filename:
<1 x 1 degree tile><quad designation><quadrant>
Where
- <tile_num> is the 1 x 1 degree tile number, composed of latitude and
longitude values
- <quad designation> is the 7.5-minute quadrangle designation based on the 8 x8 grid
- <quadrant> is the quarter-quad value
(1-4, clockwise from the northwest quadrant).
For example, the southwest quadrant of the Urbana, IL quadrangle is 40088A24, where 40 is the tile latitude, 088 is the tile longitude, A2 is the quadrangle location in the tile, and 4 is the southwest quadrant of the quadrangle. Names are independent of file format. This nomenclature is applicable to the original
DOQ files (GeoTIFF) or the MrSID compressed files (SID).
- QUADNAME
- The USGS name of the quadrangle (non-codified, alphabetic name, ie. Urbana, IL)
- QUADRANT
- The quarter-quad direction (non-codified, alphabetic name, i.e. NW/NE/SE/SW)
- UTM_ZONE
- The UTM zone of the DOQ (either 15 or 16 in Illinois)
- COLUMNS
- Number of pixel columns ("samples") in the original GeoTIFF image
- ROWS
- Number of pixel rows ("lines") in the original GeoTIFF image
- RMSE_XY
- Root Mean Square Error in the imagery (measured in meters)
- SRCIMG_ID
- Unique source image identification number for original photography
- SRCIMG_D
- Date of original photography (yyyymmdd)
- SRCDEM_D
- Date of DEM data used for orthorectification (yyyymmdd)
- ORIG_SIZE
- Size of the original GeoTIFF image, as delivered from the USGS (in megabytes)
- COMP_SIZE
- Size of the compressed MrSID .sid image, as modified by the ISGS (in megabytes)
- RATIO
- Actual compression ratio. A target ratio of 15.0:1 was used on all imagery, but the actual compression ratio varies between images.
- DOQ_DATE
- Date of production of original GeoTIFF imagery at USGS (yyyymmdd)
- SID_DATE
- Date of production of the compressed MrSID imagery at ISGS (yyyymmdd)
- SID_TIME
- Time of production of the compressed MrSID imagery at ISGS (hh:mm:ss)
Image boundary coordinates are taken from the tic marks placed in the image.
The actual image extends approximately 300 meters beyond the boundary of the
tic marks so that image mosaicking can be smoother. Primary tics (NAD83) are
solid "+" symbols and secondary tics (NAD27) are dashed "+"
symbols very near the primary tics.
- W_LONG
- West longitude of bounding quarter-quadrangle
- E_LONG
- East longitude of bounding quarter-quadrangle
- N_LAT
- North latitude of bounding quarter-quadrangle
- S_LAT
- South latitude of bounding quarter-quadrangle
- ORIGIN_X
- x-coordinate of the imagery origin
- ORIGIN_Y
- y-coordinate of the imagery origin
- SORIGIN_X
- x-coordinate of the imagery secondary origin
- SORIGIN_Y
- y-coordinate of the imagery secondary origin
- NW_X
- x-coordinate of the northwest quarter quadrangle corner (solid +)
- NW_Y
- y-coordinate of the northwest quarter quadrangle corner (solid +)
- NE_X
- x-coordinate of the northeast quarter quadrangle corner (solid +)
- NE_Y
- y-coordinate of the northeast quarter quadrangle corner (solid +)
- SE_X
- x-coordinate of the southeast quarter quadrangle corner (solid +)
- SE_Y
- y-coordinate of the southeast quarter quadrangle corner (solid +)
- SW_X
- x-coordinate of the southwest quarter quadrangle corner (solid +)
- SW_Y
- y-coordinate of the southwest quarter quadrangle corner (solid +)
- S_NW_X
- x-coordinate of the northwest quarter quadrangle secondary corner (dashed +)
- S_NW_Y
- y-coordinate of the northwest quarter quadrangle secondary corner (dashed +)
- S_NE_X
- x-coordinate of the northeast quarter quadrangle secondary corner (dashed +)
- S_NE_Y
- y-coordinate of the northeast quarter quadrangle secondary corner (dashed +)
- S_SE_X
- x-coordinate of the southeast quarter quadrangle secondary corner (dashed +)
- S_SE_Y
- y-coordinate of the southeast quarter quadrangle secondary corner (dashed +)
- S_SW_X
- x-coordinate of the southwest quarter quadrangle secondary corner (dashed +)
- S_SW_Y
- y-coordinate of the southwest quarter quadrangle secondary corner (dashed +)
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