# Erratic apply-scale behavior with vert groups and displacement modifier

When trying to scale an extruded and assigned faces vert group back to zero on the Z-axis after applying a displacement modifier, it either seems to work correctly, or the entire mesh goes flat, as if I'd never applied the modifier in the first place. I know individual origins is supposed to be selected, but sometimes it works, sometimes it doesn't. Any help would be deeply appreciated. My workflow:

2. apply two array modifiers with one offset along Y-axis –>
3. UV unwrap –>
4. E RMB faces to extrude and hold geometry –>
5. assign these to a vert group for displacing –>
6. apply displacement modifier and adjust as needed –>
7. tab into edit mode and select only that faces vert group from individual origins
8. S Z to 0

Am I missing something here?

The first image shows the error. I've added and applied the displacement mod; selected only the faces vert group; then scaled that group to 0 along Z.

The below image shows what's supposed to happen, but often I can only get this to work after switching back and forth between the indiv. origins and 3D cursor tabs, and toggling between the faces/vertices tabs.

• I'm confused on what you are trying to accomplish. When you say apply the modifier are you using the apply button on the modifier to make it permanent? When you use S Z 0 you'll be flattening the selected vertices, effectively undoing what the displacement modifier was doing. Please add some images that illustrate what you have and what you are trying to do. – cegaton Mar 30 '16 at 18:24
• Knew I should've added images. Yes, I applied the displacement mod to make it permanent. The first image above shows what happens when the error occurs. The second is the correct mapping. – j_a_l Mar 30 '16 at 19:13
• To be clear, I'm just going for a simple, but what I understand to be, accurate visualization of bit depth via a displacement mesh, so that I can alter it from there as need be. I was following this tutorial: (youtube.com/watch?v=ZB3UEnCE_T8). – j_a_l Mar 30 '16 at 19:36

I just realized that you typed out the correct step in #7, however, it seems that you have mistaken the icon per your screenshot on your erroneous one (it's easy to do, because it looks very similar). Be sure to set your pivot point to individual origins.

Here's the behavior of doing S Z 0 using the different pivot modes:

Active Element:

When using the active Element, Blender is considering the origin of whatever your last active selected item is (in this case, the last face selected). In other cases/selection modes, it could be the last selected vertex/edge, as well as in Object mode - this would be the last selected Object, and would consider its origin as the pivot center.

Median Point:

In the demonstration below, I used two selections for simplification, however when using this mode, Blender will take whatever is selected and calculate an averaged pivot location, and use that.

Individual Origins:

For this mode, Blender considers the "origin/pivot point" whatever the median pivot would be if you were to use median, and pick only one object. The difference is that it does this on everything selected.

3D Cursor:

For this mode, anything selected will pivot from the Viewport's 3D cursor location.

Bounding Box:

This one acts a lot like Median Point, although instead of thinking about calculating a median like origin between object origins, it calculated the extremity boundaries of the items selected, and then brings you to the mid/center point of that (in this example it is hard to tell the difference between Bounding Box & Median Point Pivot Mode.

• I'm not trying to apply a shape key. You're probably more experienced than me – still pretty new to Blender – but I'm not missing the point of what cegaton said. Rather, I was just following the above-mentioned tutorial, and its author was indeed achieving a more nuanced displacement mapping by scaling the assigned top face vert group to 0 on zed AFTER applying the dis mod in object mode. Do I know why? No I do not. But it does create a more detailed mapping for me as well, when I can get it to work. If you're interested, that tutorial is here: youtube.com/watch?v=ZB3UEnCE_T8. – j_a_l Mar 30 '16 at 23:14
• @j_a_l - Just updated my answer, it should solve your problem. – Rick Riggs Mar 30 '16 at 23:38
• thanks for the update. Yeah, I saw that discrepancy earlier in my screenshot as well. Don't know how that happened. I guess what I was doing was starting from an individual origins pivot, instead of 3Dcursor, which was causing the problem when trying to S Z to 0. To yours and @cegaton's point though, I still don't why this works re the more detailed, voxelized mapping. Any idea? Maybe because after applying the dis mod, the mesh is being treated such that every other extruded, displaced vert group is 0, regardless of where they're positioned on Z? Hope this makes sense. – j_a_l Mar 31 '16 at 13:37
• More precisely, if I start from 3D cursor – anything other than Individual Origins, and then select the latter when scaling to 0 on zed, it works every time. – j_a_l Mar 31 '16 at 13:47
• @j_a_l - I am working on an explanation of this, and will make it pretty thorough as an appended part of my answer, I need a little bit of time though. – Rick Riggs Apr 1 '16 at 1:14