Editing and Creating Objects

Working with AutoCAD Files

Using File Link with AutoCAD Drawings

 

Autodesk 3ds Max Tutorials > Project Management > Working with AutoCAD Files > 

Importing 3D AutoCAD Models

AutoCAD creates both 3D solids and 3D surfaces, both of which are imported into 3ds Max as surface models. In most cases, the conversion process is completed with no problems; however, there are occasional errors that must be addressed.

1. Reset 3ds Max.
2. Choose File menu > Import and browse to the \tutorials\designviz folder. Import the normals.dwg file.
3. On the AutoCAD DWG/DXF Import Options dialog, turn off Auto-Smooth in the Geometry Options group and turn on Views And Cameras in the Include group and then click OK.

   

4. Make sure the Perspective viewport is active and press the C key.

   This activates the Camera:Globe1 viewport.

5. On the main toolbar, click Quick Render.

   

   The surfaces are not smoothed, and several faces on the globe and base do not appear because their surface normals are flipped.

6. Reset 3ds Max, and then re-import the normals.dwg file.

   This time, turn on Auto-smooth and Unify Normals, as well as Views And Cameras in the Include group. Click OK.

   

7. View the scene through the Camera:Globe1 camera again.
8. Render the scene again.

   The imported objects now appear smooth and the face normals are all properly unified to face the same direction.

   

Adjust the Smoothing and Normals Manually

If you've imported a large DWG file, you might not want to re-import the model. Especially, if there are only a couple of objects that have insufficient smoothing or flipped normals. You can adjust those faulty objects manually using the Smooth and Normal modifiers.

1. Reset 3ds Max and then re-import the file.

   Make sure the Auto-smooth and Unify Normals switches are turned off, and turn on Views And Cameras in the Include group. This duplicates the settings you used at the beginning of this tutorial.

   

   Click OK to import the DWG file.

2. Change the Perspective viewport to view the scene through the Camera:Globe1 camera by pressing the C key.
3. Select the Layer:Globe object.
4. Open the Modify panel, and unroll the modifier list.
5. Scroll down the list and choose the Normal modifier.

   Now the face normals of the globe are reversed.

   

6. In the Parameters rollout, turn on Unify Normals and turn off Flip Normals.

   The object’s normals all face in the correct direction.

   

7. Open the modifier list again and add a Smooth modifier.
8. In the Parameters rollout, turn on Auto Smooth.

   The Layer:Globe object is smooth.

   

   TipKeep in mind that modifiers are evaluated from the top of the stack to the bottom. By adding the Normal modifier before the Smooth modifier, the faces that were originally flipped will also have their smoothness corrected by the Smooth modifier. If you reversed the order, you would have a model that has all the faces visible, but the newly flipped faces would not be smooth.

   

   The same model with swapped modifiers.

9. Repeat the process on the Layer:Base object.