What is a ʼCTB Fileʼ (Color-dependent Plot Style) in BricsCAD?

ByCADbrief Staff

Short Answer

A CTB file in BricsCAD is a color-dependent plot style table that maps object colors to print settings like lineweight, screening, and output color during plotting, typically managed through PLOT. The most common professional method is assigning colors by layer, then selecting the CTB in Page Setup. Limitation: CTB only works in color-dependent plot style drawings.

What You Need to Know Before

Warning: A CTB file does not control object display in model space; it only affects plotted output. A common failure is using the wrong drawing plot style mode, because STB-based drawings cannot use CTB tables unless the drawing is converted first.

How to Use a CTB File in BricsCAD

  • Command: PLOT

  • Shortcut: Ctrl+P

  • Quick Steps:

    1. Open the drawing, then go to the Ribbon or press Ctrl+P to start PLOT.
    2. In the Plot dialog, choose your printer/plotter and paper size, then select the required CTB file in Plot style table (pen assignments).
    3. Enable Plot with plot styles, check the preview, and plot or save the setup for the layout.

Variables & Settings

  • Key Setting: Plot style table (pen assignments)

  • Expert Setting: This dropdown defines which CTB file controls plotted lineweight, screening, dithering, and output color. If Plot with plot styles is off, the CTB is assigned but not applied to the output.

Why it Fails

  • Cause 1 (Geometry): Objects use unexpected index colors, so the CTB maps them to the wrong lineweight or screening at plot time.
  • Cause 2 (layers/Locks): Layer colors were changed or overridden in xrefs, so plotted results no longer match the office CTB standard.
  • Cause 3 (Command/Logic): The drawing is using named plot styles (STB mode), so CTB files are unavailable or ignored in the current workflow.

Quick Fix & Best Practice

  • Quick Fix: Run PLOT, select the correct Plot style table (pen assignments), and make sure Plot with plot styles is turned on before previewing.
  • Manager’s Verdict: Use CTB when your office still plots by standard layer colors and needs simple, consistent output. Avoid it when projects require flexible per-object style control across multiple consultants.

FAQ

Can BricsCAD use both CTB and STB files?

Yes, but a drawing is normally set up for one plot style mode at a time.

Does a CTB file change layer colors on screen?

No, it only affects plotted output, not model space display colors.

Where should CTB files be managed in practice?

In a shared office standards location so all users plot with the same approved table.

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