September 14, 2011

AutoCAD Plotting – What Happened to the Colors?

As the Support Dispatcher at Ideate Inc. I have seen a surge of cases that center around printing in AutoCAD. In particular we have customers who are unable to print because their .CTB files are missing. Usually this has been caused by the drawing being set to use .STB files for printing instead of .CTBs. Here are the differences between the two and the particulars of switching a drawing from one type to the other.

CTB Plotting
Most users are familiar with .CTB files, or ‘color-dependent plot style tables’. These files process the drawing when printing and assign lineweights and other plot settings to printouts based on the color of the objects, which can have properties that reference the object properties.

STB Plotting
In 2000 Autodesk added an alternative print style that used .STB files called ‘named plot styles’. In this style the plot settings are assigned to a name and that name is applied to layers or specific objects. Some of these settings can be set to ‘By Object’. These will then look to the object properties, which is often set to ‘By Layer’. In this setup the colors in the drawing only affect the default color the object prints as when ‘By Object’ is specified for color in the named style.

Since the named styles can be applied to specific objects, the way that an object looks in the drawing may not reflect how it looks when printed. This requires test plotting or plot previews to catch problems with drawing appearance.

Starting New Drawings
There are two versions of each template shipped with the program, each associated with a different plot style. When creating new drawings, be sure to use a template that reflects the style that you want to use. The process of switching styles can become complicated in a drawing file that contains a lot of objects. We see this in support when users don’t notice the discrepancy until they try to print after making significant progress in a drawing.

Converting Colors to Named Styles
There are two steps to converting a drawing from .CTB to .STB
    AutoCAD needs a .STB file to use to convert the plot settings when the drawing is converted. This .STB file must have been converted from a .CTB file, preferably the main one used in the drawing that is to be converted. This associates a color mapping to the .STB file. This conversion process is independent of the drawing that is open, converting all the colors in the CTB and consolidating them into unique styles
    (Note that a .STB file that has color mapping will not be fully editable as long as the mapping remains. It can be removed in the editor, but it will then no longer be able to convert files.)
    When converting a drawing, styles are applied to the layers based on their color automatically. For objects that have a color different than ‘By Layer’ the named style for that color is applied directly to the object. Objects in a converted drawing retain all of their properties.
Converting Named Styles to Colors
There is no actual conversion applied to a drawing when it is changed from .STB to .CTB. The drawing will not remember any of the named style settings. Any object that was set to a specific named style will revert to printing based on the color property. These objects will print differently and it can be difficult get the drawing to print the same as before the conversion. As a result it is recommended that these objects be identified before the drawing is converted and their color changed to match the .CTB file that will be used after the drawing is converted.

Sharing Drawings
As always, it is best practice to include the file(s) you use to plot whenever you send out a drawing. When receiving these files, use the STYLESMANAGER command to copy them into your plot style folder.

Related Command List
STYLESMANAGER – Opens the folder location of the .CTB and .STB files which should also include a link to the creation wizard. Plot tables can be edited by opening the file.

PSTYLEMODE – reports which style the current drawing is using. (1=.CTB, 0=.STB)
CONVERTCTB – converts a .CTB plot file into an .STB plot file. It is not possible to convert a .STB into a .CTB
CONVERTPSTYLES – converts the current drawing between .CTB and .STB.

PLOTSTYLE – controls the style that is applied to new objects in .STB style drawings. In most cases it is recommended that this be set to ‘By Layer’ (CPLOTSTYLE is the command prompt version.)

DEFLPLSTYLE – controls the plot style that is applied to existing layers in a pre-2000 .dwg or for ‘Layer 0’ when not using a template. (1=.CTB, 0=.STB)
DEFPLSTYLE – controls the plot style that is applied to existing objects in a pre-2000 .dwg or when not using a template. (1=.CTB, 0=.STB)
PSTYLEPOLICY – controls the plots style that is applied to existing objects in a pre-2000 .dwg or when not using a template. (1=.CTB, 0=.STB)

Jesika DiGregorio
Support Intern

Jesika received her Bachelor of Architecture from the University of Oregon in Eugene, Oregon where she worked on construction of a student-designed structure. Her work experience includes Junior Designer at an award-winning firm specializing in architecture and land planning, and Intern Architect at a firm that provides services in planning, design, construction documents and construction administration for projects of all sizes. Jesika provides online and phone technical support to Ideate clients from the Ideate Authorized Training Center in Portland, Oregon.

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