3D Mesh features do not support cropping within mesh objects. With a specified export bounds, mesh features inside the export bounds will be exported, uncropped. Mesh features with no part inside the export bound will not be included in the export.
The general rule that data is exported in the current display projection set in the Configuration applies for most 3D Format exports. For some applications, it may be desirable to set the display projection to a custom projection that specifies an origin inside or near the actual 3D data, such as a custom Orthographic projection. This will ensure the vertices of the mesh are stored in small values close to the origin, which may reduce the file size and improve the use in 3D applications that are not geographically aware.
For more information see Working with 3D Models
The supported formats for export include: