Just thought I'd share this, since I've read some asking if it is possible in P3D.
For Isometric view in Orthographic mode I proceeded like this:
- I open the drawing in the project in P3D. Right-click on it in the Project Manager and chose 'Export to AutoCAD'
- I save the exported file.
- After creating an Orthographic drawing of the P3D drawing, I select the model space tab in the Orthographic drawing.
- There i chose attach x-ref and select the earlier exported file. I suggest to place the x-ref way off from the original coordinates.
- Then back to paper space in Orthographic drawing and create a new viewport. Not via the usual 'Create View', but by command VIEWPORTS.
- There just zoom in on your x-ref and there you have it. Complete freedom of view in Ortho mode
Hope this helps.