Transform vs Modify

Written by Conny Klasson, februari, 2003, any comments are welcome.

Transformation in 3ds max takes place when you move, rotate or scale objects. This should not be confused with modifying objects. Move and rotate should not cause any trouble. The objects are not altered they just appear at another place (or angle). The scaling tranform (non uniform scaling in particular) is a bit tricky. When scaling an object it looks like the object has been modified, in fact, it's the same object that appears at another scale.
Here are two equal boxes with 10 height segments.

We shall now extend the boxes, the left one with non uniform scale and the right one with the object parameters in the modify stack.

 

 

Below you can see the effect of scaling the left box's z-axis from 100% to 150%.
And change the right box's Height parameter from 100 to 150 units.

 
They still look like two equal boxes, but they have different sizes and one of them is scaled.

Now apply the bend modifier to both boxes, set the bend angle to 180 degrees.
Here are the results of our work so far:
What happened here? Why did'n the Bend modifier do the same thing to both boxes?

We did the scaling before the bending, but the scaling transform is performed after the modifiers in the stack. Witch in this case causes an unpredictable result.

To avoid this there is a modifier called XForm (tricky short version of "Transform"). Use it to convert a transform to a modifier.

First reset the scale of the first box to 100%.
Note: There is a Reset XForm feature in the Utilities tab.
Now apply the XForm modifer. Put it below the Bend modifier. Select the box object at the bottom of the list before selecting XForm from the Modifier List.
If the modifiers are in the wrong order in the stack simply rearrange them with a drag n' drop operation.The stack should look like this.
Select XForm in the stack and rescale the left box's z-axis to 150%. The non uniform scale operation is now a part of the modifier stack and will be treated as a modifier rather than a transformation.

Now we have achived the same result in two different ways.
Caution: Don't do this at home.
It's strongly recommended that you use one method to produce the same result.

Try move the XForm modifier to the top of the list. Now we are back to the previous result, but in a more predictable way.