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Manual - Blender 2.4

[edit] Advanced Mesh Modeling

Editor’s Note

This is more of a tutorial than a user manual, but we don’t have anything else at the moment that covers the topic. --Roger 02:17, 29 May 2007 (CEST)

[edit] Symmetrical Modeling

A plane.

You often need to model objects which exhibit some sort of symmetry. For radial, rotational or multiple symmetry the best approach is to carefully model one base structure and then, as a last step, duplicate the base cell via Spin Dup or whichever command is most appropriate. For objects with bilateral symmetry, those with one plane of symmetry, such as most animals (humans included) and many machines, the above method implies modeling one half of the object, and then mirroring a duplicate of the first half to get the whole object. Since it is usually difficult to attain correct proportions by only modeling a half, it is possible to duplicate the half before it is completely modeled, and act on one half and automatically update the other.

Right half.

In Front View, add a plane or whatever (A plane). Consider it as a starting point for one half of the object. Let’s say the object’s right half, which for us in frontal view is on the left of the screen. The plane of symmetry is the yz plane. Move the mesh, in Edit mode, so that it is completely on the left of centre. Delete some nodes, and add some others, to give it its general shape, as in (Right half).

Mirroring the linked duplicate.

Now switch to Object mode and, with the half selected, make a linked duplicate with AltD. Press Esc to exit from Grab mode and press N. In the Transform Properties panel which appears, set SizeX to -1.0 (Mirroring the linked duplicate). This effectively mirrors the linked duplicate with respect to the object’s centre, hence the importance of keeping the centre on the plane of symmetry.

Editing one half.

Having linked-duplicated the object implies that the two objects share the same mesh data, which is implicitly mirrored by the unitary negative scaling along the x axis, which is normal to the symmetry plane. Now you can edit either of the two halves. Since they share mesh data any change, be it an extrude, delete, face loop cut etc… immediately reflects on the other side (Editing one half).

By carefully editing one half, and possibly by using a blueprint as a background to provide guidelines, very interesting results can be achieved.

A head. Left: Edit mode; Centre: Object mode; Right: Joined.

As a final step, when symmetrical modeling is complete, the two halves must be selected and joined into a single object (CtrlJ). This makes the seam (very visible in A head. Left: Edit mode; Center: Object mode; Right: Joined., centre) disappear. Once you have a single object (A head. Left: Edit mode; Centre: Object mode; Right: Joined., right), you can start modeling the subtle asymmetries which every being has.

Note

In Blender 2.33 and earlier versions the OpenGL implementation causes mirrored linked duplicates to have wrong normals, so that one of the two halves is black. This is fixed in Blender 2.34, but older versions can use this technique anyway by deactivating Double Sided for the mesh, while symmetrical modeling is used.

[edit] Noise

Use modifier!

Noise is quite an old feature. The recent Blender versions have a much more flexible tool to realize these sort of effects: the Displace modifier. You are strongly encouraged to use it rather than the Noise tool – some of the key advantages of the modifier are that he can be canceled at any moment, you can precisely control how much and in which direction the displacement is applied, and much more…

Noise button in Editing context.

The Noise function allows you to displace vertices in a mesh based on the grey-values of a texture applied to it. So, you must have a texture assigned to the material, even if that texture is not Mapped To anything. In your texture, you should enable No RGB to convert colour textures to a gradient. You should also have subdivided your object enough to have many vertices to act on.

Use Noise to generate great landscapes or make mesh surfaces more real-world (pitted, un-smooth). The Noise function displaces vertices along the object’s ±Z-Axis only. To deform your mesh’s other dimensions, simply rotate your object and apply rotation, or rotate the vertices in Edit mode, and apply Noise. Then, rotate it back again to get your original orientation.

Noise permanently modifies your mesh according to the material texture. Each click adds onto the current mesh. For a temporary effect, map the texture to Displacement for a render-time effect. In Object/Edit mode, your object will appear normal, but will render deformed.

[edit] Example

Subdivide tools in Specials menu.

Add a plane and subdivide it at least five times. To do that you can either use the Subdivide or Subdivide Multi entry in the Specials menu accessed via W; see (Subdivide tools in Specials menu). Using Subdivide Multi is faster and easier. Select Subdivide Multi and enter 5 for the Number of Cuts popup dialog.

Now add a material and assign a Clouds texture to it. Adjust the NoiseSize to 0.5. Choose white as the colour for the material and black as the texture colour, to give us good contrast for the noise operation.

Ensure that you are in Edit mode and that all vertices are selected, then switch to the Editing context (F9). Press the Noise button in the Mesh Tools panel (Noise button in Editing context) several times until the landscape looks nice. (Noise application process) is an example of applying the noise tool, showing the original – textured – plane as well as what happens as you press Noise. From top left to bottom right: plane with texture, sub-divided plane, Noise button hit 2, 4, 6 and 8 times.

Noise application process.

Remove the texture from the landscape now because it will disturb the look. Then add some lights, some water, smooth the terrain, and so on (Noise generated landscape).