If you're working with AutoCAD 3D and need to get a bottom view of your model, the base command is the key to achieving this. Follow these steps to easily navigate to the bottom view:

1. Open your AutoCAD 3D model and navigate to the view you want to adjust to the bottom view.

2. Once you are in the desired view, type 'base' into the command line and press Enter. This will activate the base command.

3. Now, click on the point in the drawing that you want to set as the new base point for the bottom view. This point will serve as the reference for the bottom view orientation.

4. After clicking on the desired point, your view will automatically shift to the bottom view, giving you a clear perspective from below.

5. You can further adjust the orientation and positioning as needed using the base command.

By following these simple steps, you can easily achieve a bottom view in AutoCAD 3D using the base command. This feature allows you to gain a comprehensive understanding of your model from all angles, aiding in the design and visualization process.