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File-naming
Convention
This page explains the
naming convention MassGIS uses for Arc Export Files, ESRI Shapefiles, and
images.
Vector Data
For data tiled
by Basin, OQ, OQE, Quad, Quad2, Town, or Watrshd2 the actual file names
in the Vector Data directories are based on the Tile-ID (i.e. Basin ID,
Orthophoto Sheet-ID, Quad-ID, Town-ID, or Watershed tile-name). For
a list of the appropriate IDs or names, please click on one of the following
choices:
By using the appropriate
ID or name you can locate the desired file.
Export Files contain
a layer abbreviation (library coverage name), tile-id, and the .e00 extension.
For example, a 25k hydro coverage for quad 50 is named hd50.e00.
ESRI Shapefiles consist
of three component files for each feature class compressed into one
self-extracting
executable file compatible with Windows 95, 98, and NT. After
downloading
the .exe file, double-click on the file in the Windows Explorer or
enter
the name of the .exe in the DOS Command Prompt window and hit return.
The StuffIt
software for Windows or the Macintosh can extract the contetnts of the
.exe files as well, as can the Unix and Linux command "unzip" (usage:
unzip <.exe file name>). This
process will extract all the files for each shapefile, with the
extensions
.dbf, .shp,and .shx. All three files are needed for
proper loading into GIS sofware that reads the Shapefile format. Because
individual shapefiles can contain only one feature type, you will need
to select the proper feature type for each dataset you wish to use, as
follows:
a - arcs;
p
-
polygons; x - points; r - routes;
g -
regions; s - sections; d - nodes
As an example, when downloading
arcs and polygons for quad 50 of 1:25,000 hydro, you would select the following
file:
hd50.exe
Running this executable as described
above will yield these files:
ARC CLASS:
POLYGON CLASS:
hd50a1.dbf hd50p1.dbf
hd50a1.shp hd50p1.shp
hd50a1.shx hd50p1.shx
(Note: the number '1' after
the feature type code is a version number, for MassGIS use.)
For data tiled by STATE,
NE, and CAPE, no tile-IDs are used. The files are named according to Library
coverage name. All files adhere to the 8.3 file naming convention.
Image Data
Images
are stored in TIFF and MrSID formats. To use these images in GIS software,
select 2 files: the
.tif (the image) and the .tfw (header
files needed for geo-referencing information) for TIFF or the .sid
(image) and .sdw (header) files for MrSID. The files are numbered
by the Orthophoto Index Sheet-ID, with the following
prefixes:
1_
- 1-meter pixel resolution 1:5,000 Black & white orthophotos
2_ -
2-meter pixel resolution 1:5,000 Black & white orthophotos
5_ -
5-meter pixel resolution 1:5,000 Black & white orthophotos
1u -
1-meter pixel resolution 1:12,000 Black & white USGS orthophotos
2u -
2-meter pixel resolution 1:12,000 Black & white USGS orthophotos
5u -
5-meter pixel resolution 1:12,000 Black & white USGS orthophotos
2c -
2-meter color orthophotos
q - Scanned
USGS Quad images, Mainland Zone (entire state, including Islands)
qi -
Scanned USGS Quad images, Island Zone (Martha's Vineyard and Nantucket
only)
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Last Updated 1/7/2004
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