As you can see, you need to click on every line in order to select and manipulate it. This means that there are no polylines in this drawing. If you were to import this file to 3DSMax, you would get empty space, no lines in the viewport. Or you would get independent lines which would need welding in max, which is very time consuming. Now look at this file.
[Click to download Dwg2Max_02.dwg]
Here we have the same house plan but done with polylines. Notice that it doesn't matter where you click, because you will always select the entire set of lines. This is how you need to have all of your lines in the drawing in order for Max to import them correctly.
If your file has only lines, you will need to "join" them so that you get polylines. Here's how you do that:
Open the file named [Click to download Dwg2Max_01.dwg]
Write "pe" in the command prompt. ("pe" means "Polyline Edit"). Then hit "enter". You will be asked to select a polyline. Pick any line you want and hit "enter" or right click on your mouse.
Since these are not polylines, the command prompt will tell you "Object selected is not a polyline . . Do you want to turn it into one?Y/N" Of course we want to make it a polyline so type "y" then hit "enter".
This will give you a menu of options: "Close/Join/Width/etc". As we want to make one big polyline out of the lines we have, type "J" for "join", then hit the "enter" key.
Then select all the remaining lines, one by one and you are done. One big polyline ready for import to 3D.
You don't need to have polylines within the layers that you won't be importing. So that should do it for AutoCAD.
Now let's go to Max.
We will need a new Max scene. The first step is to use the same units that we used in the AutoCAD drawing, which are meters. Go to the "Customize" menu, then pick "units setup". If your Cad file was done in feet or inches, then you will select those units in Max as well.
Our Max space is now ready for importing the floor plan. Click on the "File" menu, then select "Import". From the window that appears, go to "files of type" at the bottom and expand the sub-menu rollout so that you can find "AutoCAD Drawing (*.DWG, *.DXF)".
Browse for your file, select it and click "Open".
After selecting your file you will get the "AutoCAD Import Options" window. Here is where we tell Max how we want to import the file. Go to the Geometry sub-menu and activate "Combine Objects by Layer". This is why we used layers in AutoCAD, so that Max imports objects by layers too. Activate "weld" and "Auto smooth" as well.
Since we "joined" the lines in AutoCAD, the weld option should not even be necessary, but we use it anyway in case any minimum distances between any missed polylines will result in closed shapes.
Now let's go to the "Layers" tab. Here we select the layers that we will use. Simply turn off the ones you don't need by clicking in the checkmark just left of the layer name, kind of like what we did in AutoCAD.
Finally let's go to the "Spline Rendering" tab. Activate "Generate Mapping Coords." This helps us when applying the materials and textures later on. Click "OK".Now we have our plan in 3DSMax, ready to be modified.