PLT (Geosoft Plot file)

Long name Geosoft Neutral Plot File
Short name PLT
File extension(s) .plt

Geosoft Plot Meta Files, in the form of .plt/.att files, are supported by the GDB library for both read and write with RST support, with some limitations listed below. GDB will generate files that conform to release 2.1 of the format specification, and can read files of any version up to release 2.1

All Graphical Entities from the .PLT file are imported, and a RST is generated while reading. Each entity is given a REPCode that points to an entry in the RST. GDB automatically generates 3 attributes that will contain representation information needed by the RST:

  REPCode       (Integer) Index to a REPCode in the generated RST.
  Angle         (Double)  Orientation for Texts and Symbols.
  TextString    (String)  Text value.

Lines, Polylines, and Polygons are imported directly. Circles (and arcs) are emulated with line segments that cover 3 degrees each (120 segments in one complete circle). When Symbols, Texts, and PolySymbols are imported some of their representation attributes (Text font, slant, symbol number, etc.) are very likely to be lost, since they cannot be remapped directly by GDB.

Old style plot files that contain only Pen Number references are also supported. In these cases, an uninterrupted set of Pen-Down moves forms a Shape, and its REPCode attribute is the Pen Number. GDB will assign an arbitrary color for each pen in the RST.

The projection on import is set to "METRE". The paper coordinates (millimeters) will be converted to ground coordinates (meters) using the scale in the PLT file. If this information is not present, then a scale of 1:1000 is assumed (1 paper mm = 1 ground m) as stated in the Geosoft specifications.

In write mode, vertices and representation attributes (if a RST is available) are exported, however, GDB attribute fields cannot be exported. The PLT file is generated with the default scale of 1:1000 and the original GDB projection (if present) will be lost. The plot extents are automatically set to be the complete layer extents.

Representation attributes from the RST are remapped to their closest Geosoft equivalent. The best results are obtained with RSTs that have been generated by this same translator while reading.

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