Idrisi Vector (DVC)

Long name	Idrisi Vector
Short name	DVC
File extension(s)	.dvc, .vec, .vct, .vdc

IDRISI vector files are supported by the GDB library for import and export. The file format contains vector and header information. Typically, data sets include two files with a common basename and the extensions .vec and .dvc. we can open with either of them.

Vector files contain the identifiers and coordinates that define vector features. Vector files may contain only one feature type (point, line, polygon or text) per file.Vector files must be accompanied by Vector Documentation files for use.Vector files may be stored as ASCII or binary files. Now we only support ASCII format.

IDRISI supports a single uniform vector file structure for points, lines and polygons. This is a feature encoded structure since each feature is described in its entirety before the next is described. For all feature types (point, line, polygon), the file consists of a sequence of numbers indicating: 1) a feature identifier, 2) the number of points that define that feature, and 3) the X and Y coordinates for each point.

Any number of features may be contained in the same file, but each file must contain only one feature type (point, line or polygon). Every file ends with a pair of zeros. The format of a text file is exactly the same as that of a point file. The vector file stores the location of the text, while the actual text labels are stored in the Attribute Values file.

Vector Documentation files store important information about the Vector file(the metadata, or header information). The following parameters are recorded in Vector Documentation files:

title: a descriptive name of the file
id type: the data type of the feature identifiers in the vector file. The coordinates themselves are always stored as real numbers. The identifier type may be integer or real.
file type: the way the file is stored in the computer. This may be ASCII or binary. We only support ASCII type file.
object type: one of point, line, polygon, or text
ref. system: the name of the geographic referencing system used with the file. This may be Plane, Lat/Long, or a specific referencing system defined by a Reference System Parameter file.
ref. units: the unit of measure used in the specified reference system
unit dist.: the scaling factor between the given coordinates and actual measurements on the ground. This will almost always be 1. This entry answers the question, "One unit in the reference system is equal to how many units on the ground?"
min X: the minimum X coordinate (left edge) of the bounding rectangle
max X: the maximum X coordinate (right edge) of the bounding rectangle
min Y: the minimum Y coordinate (bottom edge) of the bounding rectangle
max Y: the maximum Y coordinate (top edge) of the bounding rectangle
pos'n error: an indication of the accuracy of the locations of features in the file. The RMS value from a digitizing or resampling operation may be recorded here.The value may also be specified as "unknown".
resolution: the typical distance between points in a feature in the Vector file

See Idrisi Raster (RDC) for information on georeferencing.