Fixing Problems in CAD Models

Fixing Problems in CAD Models

Resolving Other Common CAD Problems

 

Autodesk 3ds Max Tutorials > Project Management > Fixing Problems in CAD Models > 

Eliminating Errant Objects

With several different layout tab and paper space options available, objects in AutoCAD drawings can be widely separated throughout model space. As a result, objects that are located far from objects you want to import may be imported as well, greatly increasing the extents of the 3ds Max scene.

Set up the scene:

• Identify which version of AutoCAD you have and then do either of the following:
  • AutoCAD 2000 or laterStart AutoCAD and choose File menu > Open. Browse to the \tutorials\designviz folder and open ts_cad_1.dwg.
  • AutoCAD R14Start AutoCAD and choose File menu > Open. Browse to the \tutorials\designviz folder and open ts_cad_1_r14.dwg.

  You're presented with a 2D drawing of an office building. Views have been set up to show plan and perspective views.

Delete errant objects:

When importing drawings into 3ds Max, it's important to manage layers effectively. If two objects on the same layer are separated by a great distance, you can start running into problems when the model is imported into 3ds Max.

1. Start 3ds Max or choose File menu > Reset to reset the scene.
2. Choose Files menu > Import.
3. In the Select File To Import dialog, set the Files Of Type field to AutoCAD Drawing (*.DWG, *.DXF) and navigate to the \tutorials\designviz folder.
4. Choose ts_cad_1.dwg or ts_cad_1_r14.dwg, depending on your version of AutoCAD, and then click Open.
5. On the AutoCAD DWG/DXF Import Options dialog, click the Geometry tab if necessary, turn on Rescale, and set the Incoming File Units to Inches. Click OK.
   NoteIf you've worked through some of the tutorials, your import settings might differ. Compare your settings with those shown in the following illustration.

   

   After the drawing is imported into 3ds Max, you'll notice that the viewport does not seem to have automatically zoomed to the extents of the imported drawing, thus causing the building to appear very small. This is a clear indication that an errant object is located a great distance from the scene. In the AutoCAD file, this object is located on the same layer as several other objects. When it is imported into 3ds Max, the objects sharing a layer are consolidated into a single entity. This wayward object cannot be deleted without also deleting the other objects that were imported with it.

6. Reset the 3ds Max scene without saving anything and minimize the program.
7. Go back to AutoCAD. At the AutoCAD command line, type Zoom E and then press Enter.

   The model space window is increased to show the entire drawing and since the main part of the drawing is condensed toward the lower left corner, it means the errant objects are somewhere in the upper right part of the viewport.

8. Use the Erase command and drag a selection window around the upper right corner of the AutoCAD viewport until the small line objects (there are four) are selected. Delete these objects.
9. Do another Zoom > Extents to display the drawing properly.
10. Save the drawing as myImport.dwg, then import it into 3ds Max again.

    

    This time the file imports and displays correctly.

    TipAnother way to ensure that only the required objects are imported is to execute the WBlock command in AutoCAD and select only the essential objects to be incorporated into a new DWG file.

Be sure to close polylines:

Most designers who work primarily with AutoCAD create drawings with lines, arcs and circles. However, using polylines to create perimeter objects offers the quickest means of converting a 2D drawing into a 3D model. If drawn correctly, a polyline can be quickly extruded into a large solid surface like a poured concrete floor or a set of walls when the drawing is imported into 3ds Max.

1. Continuing from the previous section, select the Layer:LEASELN2 object and apply an Extrude modifier.
2. Adjust the Amount value so that you can see the extrusion in the viewport.

   

   Notice that the spline that follows the perimeter of the building is extruded, but the top is not capped. This is an indication that the polyline was not closed in the AutoCAD drawing.

3. Delete the Layer:LEASELN2 object.
4. In AutoCAD, open the myImport.dwg. Select the blue polyline on the LEASELN2 layer.
5. At the AutoCAD command line, type Pedit and then press Enter. Next, type C (for Close) and then press Enter twice.

   You have closed the gap in the polyline with an additional segment.

6. Save the drawing.
7. In 3ds Max, begin the process of importing the drawing again. Stop when the AutoCAD DWG/DXF Import Options dialog opens.
8. In the AutoCAD DWG/DXF Import Options dialog, switch to the Layers panel.
9. Activate the Select From List option. Select only the LEASELN2 layer, then click OK.

   Only the objects on the LEASELN2 layer are imported.

10. Select the Layer:LEASELN2 object again and apply the Extrude modifier.

    This time the spline is capped.

    TipIf several polylines must be closed in AutoCAD, type Pedit on the command line, then press Enter. Type M to allow multiple selection and select all the polylines that need to be closed.

Use File Link instead of Import:

The section you just completed made exclusive use of the import functionality of 3ds Max, but what would have been different if you had used the File Link Manager?

1. Using AutoCAD, open the file ts_cad_file_link.dwg and choose File menu > Save As.
2. Name the file myImport2.dwg.

   Doing this preserves the original drawing so the tutorial can be easily repeated.

3. In 3ds Max, choose File menu > Reset and discard the current scene without saving.
4. Choose File menu > File Link Manager and click the File button on the Attach panel.
5. Open myImport2.dwg, turn on Rescale and click the Attach This File button.

   There is now an active link between the drawing in AutoCAD and 3ds Max.

   

6. Select the Layer:LEASELN2 object and apply an Extrude modifier.
7. Adjust the Amount value so that you can see the extrusion in the viewport.

   

   Just as in the last section, the object is not capped due to the open polyline. Here's where the workflow process differs.

Fix the drawing and reload the link:

1. In AutoCAD, enter the Pedit command and select the blue polyline on the LEASELN2 layer.
2. Type C for Close and press Enter twice to complete the command.
3. Save the drawing.
4. In 3ds Max, click the Files tab of the File Link Manager dialog.

   The red flag means the drawing has been updated.

   

5. Make sure Show Reload Options is active and click the Reload button.
6. Click the Advanced tab and turn on Selective Reload.

   

7. Choose Selected In Scene and click OK.

   

   Since the Layer:LEASELN2 object was left selected after applying the extrude modifier only that object is reloaded from the drawing file. You could have also chosen from the list of linked objects by choosing the Layer:LEASELN2 object and clicking the Invert button.