Hi,
If you are using Revit 2017 or previous releases of Revit, the option TrueColor means that is uses the color specified in Object Styles.
If you use Revit 2017.2/2018, there is a new export option “Specified in view”, which uses the color from the assigned material colors of the object surface patterns. This option displays colors that are more true to those seen in the Revit view.
More information can be found here.
Hope this helps!
Anna
Anna
QA Analyst
Autodesk, Inc.