When you import a file, the format of the imported file may support varying qualities of geometry. These variations are caused by the file type, the export settings for the originating application, and the Revit import settings.
Some tools and capabilities in Revit LT require specific types of geometry. For example:
You can import many different types of file formats into Revit LT. When you export a file from the originating application for use with Revit LT, you can set a variety of export options. With these many variations of file formats and export options, it is important to ensure that the exported file provides the geometric data needed for the Revit LT capability that you plan to use. To optimize results with various file formats, consult the documentation provided with the exporting applications.