# Earth: Geothermal Layers

Hi,

I would greatly appreciate any pointers you can give on how to create a better image. Here is what I did:

1. Created a sphere.
2. Created a plane.
3. Lopped off a vertex from the plane.
4. Extruded the plane to get a triangular “pie” shape.
5. Performed the appropriate boolean operation on the sphere and pie.
6. Removed all extraneous parts of the pie, leaving just the inside cut-away shape.
7. Duplicated and scaled the cut-aways.
8. Painstakingly placed the cut-aways in a layer.
9. GIMP’ed the numbers and arrows on the final image.

What I don’t like about this is that positioning each of the cut-away layers was not as precise as it could have been. As such, the “crust” layer (layer #1) is showing more blue on the left than it does on the right. Similarly, there are extremely subtle shadows between the layers. Lastly, the cut-away lines aren’t perfectly straight (because each layer is raised ever-so-slightly above the previous).

Thoughts and critiques are highly desired.

T

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Add a UV sphere. Duplicate it, and scale it larger. Duplicate again, scale up again. (You can use numerical input for the scale operation to get the thickness you want between spheres. I believe you enter a percentage of the previous size.)

Cut away a spherical triangle of the outer sphere, then cut the exact same faces from the inner spheres. (Easiest in face mode, switching from view to view, and zooming in to get those close to the pole.)

Switch to edge mode, and connect the edges of the inner and outer spheres to make the cut away planes. (The trick here is to pick the correct edge on the inner sphere, which is not cut. I went to top view, zoomed in to the pole, then selected the edge next to the cut edge. I then tilted the view slightly with numpad 2 and 6, and selected the correct edge. Once you have one edge, the rest are easy.)

Make the new faces by selecting two edges, one on the inner sphere and one on the outer sphere, then press f to make the face.

It’s tedious, but it’s exact.

[EDIT] You may want to make each sphere a vertex group, before you add the cut away planes. That way you will be able to select them easily to make any adjustments once you have everything assembled and colored. [/EDIT]

[EDIT2]
OK, save yourself some work: Add one sphere, make it a vertex group, duplicate it and make another sphere. Make the second sphere a different vertex group. Cut the triangle out of the outer sphere, as described above, and make the new faces.

Once you have the faces complete, select everything, deselect the two spheres and make the new faces a vertex group. Then, with the faces and the outer sphere selected, duplicate and scale up. You will get a new sphere AND the faces connecting them. Select just the new faces, make a vertex group, select all and deselect all vertex groups, leaving the new outer sphere selected, make it into a vertex group.

Do the select the outer sphere and connecting faces, duplicate and scale up as many times as needed, making sure to make the new faces and sphere their own vertex group.

This way, you will only have to build the connecting faces once, and the duplicate/scale operation will automatically create the next layer for you. Also, when it comes time to select the cut away planes for coloring, you’ll already have them set up as vertex groups so they’ll be easy to select.

[/EDIT2]

Looks cool, but I think it should be easier with a cube.

Hi, Orinoco.

Wow. Thank you for the in depth response. I’m not quite sure how to make a ‘vertex group’ but I will try again and see what happens. It looks like it will also take care of the rough edges I had on my original.

Hi, Rolandixor.

I’d use a cube, except that people stopped believing the Earth was flat a very long time ago. I think we should present the most ‘modern’ version of the Earth as possible. In this case, something shaped like a ball.

T

Sorry, use a cube instead of a plane, for the boolean operation… it should save you trouble…

I did not look closely enough at that duplicated sphere and cut away plane to notice that they weren’t connected. Sorry.

Start with a sphere, and in Edit mode duplicate it and scale it up. Make the cutout in the outside sphere, then connect the edges of the inner and outer sphere to make the cutaway planes. Do this connecting by selecting one edge on the inner sphere, one edge on the outer sphere, and making a face with fkey. Then, with the faces selected as shown above, in Edit mode, duplicate and scale up.

What’s not visible in this is that the new faces aren’t attached to the old faces, as I assumed they would be. Oops. A close up in vertex select mode, showing the problem

There’s a gap. Fortunately, in this case, the gap between vertices that should be connected is much smaller than the distance between vertices that should remain apart, so we can use the remove doubles tool to correct the problem.

Select everything, then raise the remove doubles limit a little bit (0.100 worked in this case.) Press the remove doubles button. You should get a little pop up that says “Removed: N” where N is the number it will remove if you confirm by clicking on the pop up. If N is 0, then the doubles limit is too small. N should be the number of little tiny gaps between the new and old cut away faces. However, the first time you do the operation, take a close look at the entire model, to make sure Blender didn’t find pairs of vertices that were within the limit that you did NOT want to remove (sometimes that happens, especially on organic models.) If Blender got overenthusiastic about removing doubles, use the undo tool (Control z), and make the doubles limit a bit smaller, or, if it’s a single pair that was mistakenly joined, temporarilly move that pair apart.

The remove doubles button and limit control is on the Editing Mesh Tools panel, just above that big Extrude button in the middle of the panel.

Hi, Rolandixor.

Sorry, I was making a terrible joke and forgot to add the smiley. Yes, I see that a cube would have been a lot faster. Thanks for the suggestion.

T

Here’s how I would make it:

2. In edit mode, select entire area that you want to be cutout

3. Extrude Region and immediately push ENTER or RMB

4. Change Rotation/Scaling Pivot to 3D Cursor

5. Scale down to the desired size

6. Loop Cut (CTRL-R) the regions inside the cutout part

7. Now you are ready to apply textures and materials

Hi, anthonyesau.

Wow, another great response. That seems to be the simplest way so far. I’ll have to try it!

Thank you,
T

anthonyesau, great solution. Simple and looks good. I tried it and noticed that it does create beveled planes between the interior sphere and the exterior sphere. Here’s a (completely tested this time) way to get rid of the beveling and make a cutaway with perpendicular sides.

Limit selection to visible (button next to face select mode button)

Use box select (b) to select a quarter hemisphere (include the pole vertex)

Inverse selection and hide (Select>>Inverse, h)

Select all three edges of the quadrant (Alt+Shift+RMB with cursor near edge)

Extrude the edges but don’t move them (e>>Edges Only, escape)

Inverse the selection (Select>>Inverse)

Make the new selection a vertex group ([Links and Materials panel, Vertex Group] New,
name the group, Assign)

Unhide the sphere and deselect all (Alt+h, a)

Select the vertex group ([Links and Materials panel, Vertex Group]Select)

Set scaling to 3D cursor (period or use the pivot selector in the 3D window header)

[Make sure the 3D cursor is still in the center of the sphere! If it’s not, get it
back to the center by switching to object mode (TAB) and centering the cursor on the
sphere (Shift+s>>Cursor->selection) ]

Scale in a small amount (s, 0.95)

Notice that the extruded edge (which is not part of the vertex group) remains in the original position on the surface of the large sphere. The large sphere, though, is connected to the vertex group, and scaling the vertex group inward causes the beveled faces. This is what we clean up next.

Deselect everything (a),

Switch to face mode (Ctrl+Tab>>Face) and select the beveled faces (Shift+RMB)

Delete them (x>>Faces)

Replace the faces with faces connecting the main sphere to the top edge of the
cutaway section.

Switch to Edge mode (Ctrl+Tab>>Edge),

select opposite edges (RMB, Shift+RMB),

make face (f)

To make the triangular faces at the pole, select edges on two sides of the triangle.

Finally, select the vertex group again, and scale it down to core size.

Perfectly perpendicular cut away planes.

Then back to anthonyesau’s method, step 6.

I thought so. I like to make jokes myself! BUT DON’T FORGET THE SMILEY! IF NOT I’LL, I’LL, uh, I’ll, am… Ah!

Another tip, If you form a set of “steps” on the cube (I’ll ad a picture If necessary) then you could make it even better…

Hi, all.

Here is what I did:

• New model (File >> New); remove cube (if exists)
• Changed to top view (NUM7)
• Edge select mode (CTRL-TAB >> Edges)
• Deselect all (a)
• Selection cross-hairs (b)
• Selected 1/4 of the sphere (drag + LMB)
• Changed view to see half sphere (NUM1)
• Changed to vertices select (CTRL-TAB >> Vertices)
• Selection cross-hairs (b)
• Deselected bottom 1/8 of sphere (drag + MMB)
• Created Vertex Group (F9, New, give name, Assign)
• Extrude region (e >> Region, then ESC)
• Clicked Rotation/Scaling drop-down icon to 3D Cursor
• Scaled to inner core size (s, 0.193, Enter)
• Changed selection mode to Faces (CTRL-TAB >> Faces)
• Selected one face of each of the three cut-away faces (SHIFT-RMB)
• Selected perimeter (G, then Similar Perimiter)
• Made the face a Vertex Group (just in case), called Cut-away.
• Selected the connecting edges of the cut-away faces (CTRL-+)
• Deselected the Cut-away vertex group, manually (CTRL-SHFT-LMB) At this point, I was ready to do the face cuts using CTRL-R. It worked like a charm.

I haven’t quite figured out how to get rid of that bevelling, but since the crust layer is 0.994 times the thickness of the whole globe, the bevelling is hardly noticeable. Now I just have to figure out how to assign materials to the different cut-away faces.

Thanks everyone for all your help!

T