Thursday, April 21, 2011

Dept. of Subtle - Text Output to DWG

With 2012 we can now map Revit fonts to fonts in AutoCAD. I can export Arial to Romans for example.

I got a request to check something out today and the results are curious. Here's a drafting view of four Arial font sizes: 1", 1/2", 1/4" and 3/32" (using view scale of 1:1).

Here's how it looks going from Arial to Arial (Revit 2012 - AutoCAD 2012).

Here's how the Text Height transferred (Revit/AutoCAD):

I used the "deepest" units setting in AutoCAD for Fractional of 1/256" so that's altered the value for 3/32" to register the "correct" amount. The decimal equivalent for 3/32" is 0.09375 though so the reported value (when I change the units to decimal instead) of 0.09220621 is also off a bit.

Then I exported from Revit Arial to AutoCAD RomanS, same sizes:

Here's how the Text Height transferred (Revit/AutoCAD):

Can't really measure text height accurately in Revit since none of the tools that measure or dimension can "touch" text. It's possible the fonts are "off" in Revit to begin with, just can't say for sure. I don't know that the inaccuracy is enough to get upset about but it doesn't result in text heights that match what you'd expect.


Matt Stachoni said...


I had this exact same conversation with a customer a few weeks ago. We investigated the problem and it's definitely something about Revit and how it treats text.

Even in Revit, many fonts do not express themselves at their specified type size. If you draw some lines 3/32" apart and place several 3/32" text types that use different fonts, some hit 3/32" but others are taller or shorter. Arial seems to be the closest, but others are often grossly inaccurate.

Another issue in Revit is whether you are using TrueType fonts or OpenType fonts. OpenType is a newer font format, created by Microsoft, built on TrueType but adding additional properties for prescribing type behavior (most useful in publishing apps).

OpenType fonts come in two flavors – those made with TrueType outlines and those made with PostScript outlines. While Windows will display both flavors equally, Revit will have an issue with PostScript-outlined OTFs. You may see filled in or missing characters when using PS OpenType fonts.

To help fix this issue, there is an online font-conversion web site at, which will convert problematic OTFs to straight up TTFs. I've had to fix several favorite fonts this way, e.g., Francis D.K. Ching's "Tekton" font.

Anonymous said...

Something else that's limiting in Revit 2012. You can't add callouts to locked 3d views, only annotate. Limits the use of the 3d views in construction documentation

TerribleTim said...

It's not just Revit 2012, I noticed this same issue in 2011 as well. It is definately something in Revit.

daveedwards said...

I noticed that the resulting DWG text size changes from font to font. Probably has something to do with the font cap height.

Also, I did verify that only Truetypes can be specified in the export - not SHXs. I guess Autodesk thinks that everyone's CAD standards no longer use SHXs.

David William Edwards

daveedwards said...

Matt -

Revit is not examining the letter "A" and internally scaling the characters so that the caps are of an exact size, as AutoCAD does. Truetypes are based on DTP conventions and cap heights have not correlation to text height. Easy to see if you compare a 72p Arial to a 72p Times New Roman in a standard Windows app like Word.

David William Edwards