VECRST -- Rasterize Vectors

This program rasterizes one or more vector segments with a provided RST into one or three raster channels.

PARAMETERS

VECRST is controlled by the following global parameters.

Name     Prompt                                  Count     Type
FILE     Database File Name                      1-64      Char
DBOC     Database Output Channel List            1-3       Int
DBVS     Database Vector Segment                 1-1024    Int
DBSL     Database Segment containing RST         1         Int
QUERY    Vector Query Selection Criteria         1-64      Char

FILI

Specifies the name of the PCIDSK file to be used. This file must contain at least one image channel and one vector segment.

  EASI>FILE="/pci/demo/irvine.pix"

DBOC

Specifies the channels output the imagery.

  EASI>DBOC=1                           | Output to channel 1.
  EASI>DBOC=1,2,3                       | Output to channels 1,2,3

  Only 1 or 3 channels may be specified.

DBVS

Specifies the vector segments you wish to rasterize.

  EASI>DBVS=2                           | Uses vector segment 2.

DBSL

Specifies the vector segment containing the RST you wish to use to rasterize the vectors with. This may be one of the vector segments specified in DBVS.

QUERY

An optional vector query expression which may be used to selectively rasterize vectors which satisfy the search criteria.

  EASI>QUERY="attribute < 10"

The program will only rasterize vectors which have a attribute values of less than 10.

The following is the grammar.

EXPRESSION: PRIMARY
             not (EXPRESSION)
             (EXPRESSION) BINARY_OP (EXPRESSION)

PRIMARY: FIELDNAME OPERATOR VALUE

OPERATOR: =
           <=
           >=
           <
           >

BINARY_OP: and
            or
VALUE: number
        "string"

FIELDNAME: valid fieldname of the vector segment or "ShapeId"

Examples:

        attribute = 1
        not (attribute = 1)
        (attribute < 12 and attribute > 4) or (group < 2)

DETAILS

The VECRST PACE program can be used to rasterize vector features into an image channel. Simple rasterization is also accomplished by the GRDVEC, and GRDPOL tasks, but the VECRST task is special in that it renders the vectors based on a Representation Style Table (RST).

An RST is used to attach complex rendering styles, such as line styles, polygon fill, fill patterns, and rendering points as text or symbols. It is the central data structure of the ACE software line, and can also be produced with the RST editor within ImageWorks. To learn more about RST's please review the ACE documentation.

The VECRST program takes one or more vector segments (DBVS) as input. Each of these is rasterized. Each layer is read in turn, and is rendered into the raster channel. Note that the vector priorities within the RST are only considered within a single vector layer. A low priority item in the second segment in DBVS will be written over a higher priority item i the first segment in DBVS.

The RST is read from a vector segment (DBSL). All vectors in this segment will be ignored, unless they are also selected in DBVS. A single RST is applied to all vector layers.

Either one, or three raster channels (DBOC) should be selected for output. If one is given the vectors will be rendered in greyscale format, otherwise they will be treated as a red, green, and blue channel.

The QUERY parameter can be used to select specific set of vectors within the set of vector layers selected.

The ADDANNO.EAS script is an example of using VECRST to burn text into an image.

EXAMPLE

  Create a rasterise vector with features assigned from an attached RST.
  Assign the RST attributes to all the vector segments in segment 25 and
  output the results to an 8 bit channel.

  EASI>FILE="Irvine.pix                 | File Name 
  EASI>DBOC=8                           | Database Output Channel List 
  EASI>DBVS=25                          | Database Vector Segment
  EASI>DBSL=25                          | Database Segment containing RST
  EASI>QUERY="attribute  > 0            | Rasterize all RST vectors

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