Readability Bias?

This is one of those Civil 3D settings you see for the first time, Land Desktop didn’t have anything similar, and you think to yourself – “I quit, I’m never gonna get this – maybe it’ll go away if I ignore it.” Nice…

Relax. This setting, as seen in any of the Label Style Composers, threw me for a loop as well, but when you dig into it, it’s a sweet setting.

The “Readability Bias” is the setting that tells Civil 3D that when it finds an object whose angle in the xy plane is “x” degrees (typically vertical), the label should flip and remain readable.

I think we were all taught in high school drafting class (you know, the old fashioned way – ink on vellum, mylar, bumwad) that if a line is slightly to the right of vertical (i.e. an azimuth of 1 degree or so), then the label should flip to remain readable from the right side of the drawing. If the same line were drawn slightly to the left of vertical (i.e. an azimuth of 359 degrees or so), the label should flip and remain readable from the left side of the drawing – matter of fact, I think this should be a law

What threw me was the default setting in Civil 3D of 110 degrees. 110 degrees in AutoCAD is equivalent to an azimuth of 340 degrees (remember in AutoCAD, 0 degrees in the xy plane is equivalent to an azimuth of 90 and angles are measured counter-clockwise) – in my simple mind, an incorrect choice.

If you want your labels to flip, stay on top of the line, and remain readable from the right side of the page as your object clears an azimuth of 0 and rotates clockwise, then set the “Orientation Reference” to “Object,” select a “Forced Insertion” of “Top,” (to ensure the label stays on top of the line), turn on “Plan Readability,” (to ensure the label is right-side-up when in a different view), set the “Readability Bias” to 90d00’01” and set the option to “Flip Anchors with Text” to “True” (so the text spins from end to end instead of mirroring itself). With these settings, the label on a vertical line will remain readable from the right side of the page – as it should be

For more information on these settings, browse the Civil 3D 2006 Help system for “HelpGeneral Tab (Label Style Composer Dialog Box)” or simply punch the Help button in a “Label Style Composer” dialog.

Cheers!