Triangles to Quads (Quadrangulate) in 3d Studio Max

Four sided polygons are very useful in 3d modeling. They sub-divide better and they smooth better. A quad always divides into a quad. You try dividing up a 5 sided shape into more 5 sided shapes! So its a good idea to stick with them. However, sometimes you import a model and all you get are triangles for whatever reason (and there are a ton of reasons), but you want to go back to those clean 4 sided polygons. What do you do? Sure you can do it manually but you can actually do it pretty quickly using the steps below.

Step 0: Clean Up! This step is a bit obvious! Make sure your starting out with nothing in your scene except for the model that you just imported.

Step 1: Place Up the Bomb The first step is put a bomb geometry space warp into the scene. Really, it doesn't matter where you put it. Well what does this do? We are actually going to blow up the model into 4 sided polygons first and then use auto edge and weld. The Bomb geometry space warp will help us blow it up.

Step 2: Attach it to the Mesh The second step is to attach the bomb to the mesh so that when it blows up it will actually do something to the mesh. To do this select the attach space warp tool (pictured right) and then click and drag it from the gemoetry to the bomb.

Step 3: Blow it Up! Just to see what the bomb does and to make sure that the bomb is taking effect, click and drag your frame counter to 10-15 or so and see that your mesh is actually being blown up. Now, keep it at whatever frame number you dragged it to. If you put it back to frame 0, this won't work.

Step 4: Put it back together. So we don't actually want to blow up our model, we want to keep all the newly formed quad pieces in one spot. So change the gravity and strength both to 0. We also want to make sure that our pieces are always four sided. So make the min and max size 2.

Step 5: Re-export/import or Collapse. I've been told that in certain earlier versions of max you can just simply collapse the mesh, to do this step, but I'm just going to give you a solution that works on all versions of max. Now with your model selected go to File -> Export Selected and export it as a .3ds file somewhere. Make sure "Preserve MAX's Texture Coordinates" is checked. Now, reset max by going to File -> Reset. You can save if you want to, but there's no real point. Now go to File -> Import and select the .3ds file you just exported. You should be back a similar screen as in Step 0.

Step 6: Auto-edge Now that we have your model back where there are individual pieces of 4 sided polygons, we can simply use auto edge to get rid of all those uneccessary edges. Click on your model, go into the modifier pane, select the edge sub-level by pressing 2 or clicking on edge in the sub level tree. Now select all the edges (Select All: Ctrl-D) and set the auto edge angle to 45 and click "Auto Edge". You'll see that all the uneccessary edges have disappeared (turned into dotted lines).

Step 7: Weld it Back Together and Your Done! We used a bomb before to blow up the model into small 4 sided pieces, now we have to put it back together. Simply go to your vertex sub-level by selecting your model and pressing 1 or selecting it from the sub level tree. Then select all vertices (Select All: Ctrl-A) and then make sure your weld threshold is 0.01 and click "Selected". There you go. You're done!