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Original Article Date: Sep 23, 1998
Learn how to customize your line weights via the plot driver file!
I have been receiving a lot of calls referring to output of line weights from MicroStation. Info and examples available at the end of this document.
Running MicroStation® 95 on a Windows platform gave you access to installed print drivers utilized by other Windows applications when you selected PRINTER.PLT as the plotter driver configuration file (default location is \USTATION\PLOTDRV). MicroStation SE offers an enhanced PRINTER.PLT file which allows users to fine-tune plotted line weights. Understanding the effects of simple modifications to the plotter driver configuration file is essential to achieving the output you desire.
Defining The Terms
It's important to understand the following terminology when working with .PLT files:
Line weight is the weight attribute assigned to an object in a design file.
Pen width is the physical plotted width of a line weight. As the pen width values increase, wider lines are plotted.
Records are the individual lines of text that make up the plot configuration driver file. Records can be modified by opening the file with a text editor, such as Notepad, and changing the parameters. For complete information on modifying plot driver files, refer to Chapter 16 of the MicroStation 95 User's Guide.
Commented records are those to the right of a semicolon. They are ignored by MicroStation.
Weight_strokes is an optional record and is commented out in the delivered printer.plt file. Pen width is the line weight divided by two in the absence of the weight_strokes record.
To modify line weight to pen width parameters, uncomment the weight_strokes record (remove the semi-colon at the beginning of the line):
This line causes line weight 2 to be plotted eight logical pen widths wide, line weight 5 to be 20 logical pen widths wide, and so on.
Controlling Pen Width
PRINTER.PLT in MicroStation SE is quite similar to its predecessor in MicroStation 95. There are, however, two new records introduced in MicroStation SE: weight_offset and weight_multiplier. Modifying these records allows you to control pen width:
weight_offset sets the minimum (thinnest) pen width to be plotted. It controls the width of a 0 weight line.
weight_multiplier determines the difference in pen width between two adjacent line weights (for example, the difference in pen width between line weights 2 and 3).
Use the formula pen width = weight_offset + (line weight * weight_multiplier) to determine pen width.
Some testing will be necessary to achieve desired results. Start testing with weight_offset=0, weight_multiplier=1 and weight_strokes uncommented. Then try changing the weight_strokes values to get proper pen widths.
Change Pen Variable
PRINTER.PLT does not support the change_pen variable, mainly because most system printer drivers do not control or limit the frequency of pen changes on output devices. When color, weight, or level are selected, MicroStation automatically sorts through the drawing so that all elements to be plotted with the same pen are plotted one after another. The pen is then changed, and the elements for the next pen are plotted. This is only a concern on devices where pen changes are very necessary (such as on a real pen plotters). Although still used, real pen plotters are rapidly becoming less and less utilized. Additionally, there are performance issues to take into consideration when using pen sorting, as any option other than change_pen=both requires that more scanner passes through the design file be done, resulting in slower plotting times. When using change_pen=both (the default if change_pen is not present), information is output in the same order that it exists in the design, thus increasing the efficiency of plotting. And while it is possible to use pen sorting to provide certain types of output priority, it is recommended to use a pen table (or even level symbology in instances where the capabilities that it provides are sufficient).
Line Weight Output
I have been receiving a lot of calls referring to output of line weights from MicroStation.
The HP4MV and many other printers can handle 600 DPI. The following lines can be added or modified to the .plt file.
;ENGLISH resolution and SIZE records
;This line is for the 11x17 tray option
;needs to be all on one line with no spaces