Mode: Object mode
Panel: Anim Settings » DupliVerts
DupliVerts are not a rock band nor a dutch word for something illegal (well maybe it is) but is a contraction for Duplication at Vertices, meaning the duplication of a base object at the location of the vertices of a mesh (or even a particle system). In other words, when using DupliVerts on a mesh, an instance of the base object is placed on every vertex of the mesh.
There are actually two approaches to modeling using DupliVerts. They can be used as an arranging tool, allowing us to model geometrical arrangements of objects (e.g. the columns of a Greek temple, the trees in a garden, an army of robot soldiers, the desks in a classroom). The object can be of any object type which Blender supports. The second approach is to use them to model an object starting from a single part of it (i.e.: the spikes in a club, the thorns of a sea-urchin, the tiles in a wall, the petals in a flower).
DupliVerts as an Arranging Tool
All you need is a base object (e.g. the tree or the column) and a pattern mesh with it’s vertices following the pattern you have in mind. In this section, we will use a simple scene for the following part. It consists of a camera, the lamps, a plane (for the floor) and a strange man I modeled after Magritte’s famous character (A simple scene to play with). If you don’t like surrealism you will find this part extremely boring…
Anyway, the man will be my base object. It is a good idea that he will be at the center of the coordinate system, and with all rotations cleared. Move the cursor to the base object’s center (this one being selected, do ⇧ ShiftS → Cursor -> Selection), and from Top view add a mesh (the example uses a circle as a pattern, with 12 vertices or so (A circle for a parent mesh). The pattern object can be a two-dimensional primitive (plane or circle), or even a three-dimensional primitive mesh (cube, tube, sphere) or a curve (two dimensional, or a three-dimensional path), or even your own custom mesh, so long as it has vertices (you cannot use a camera, for example, but you can use a large landscape mesh if you want to plant trees - trees being your base object).
In Object mode, select the base object and add the circle to the selection (order is very important here). Parent the base object to the circle by pressing CtrlP. Now, the circle is the parent of the character (The man is parented to the circle).
Wow, isn’t it great? Don’t worry about the object at the center (In every vertex of the circle a man is placed). It is still shown in the 3D views, but it will not be rendered. You can now select the base object, edit it in Edit mode (scale, rotate,… – be careful with the Object mode: scaling, among others, might bring up some problems when applying rotation to DupliVerts, as we will see soon), and all DupliVerted objects will reflect the changes. But the more interesting thing to note is that you can also edit the parent circle.
The base object is not rendered if DupliVerted on a mesh but it is rendered if DupliVerted on a particle system! This doesn’t appear to be true on Blender 2.45 and later.
Select the circle and scale it. You can see that the mysterious men are uniformly scaled with it. Now enter the Edit mode (⇆ Tab) for the circle, select all vertices (A) and scale it up about three times. Leave Edit mode and the DupliVerted objects will update (Changing the size of the circle in Edit mode.). This time they will still have their original size but the distance between them will have changed. Not only can we scale in Edit mode, but we can also delete or add vertices to change the arrangement of men.
Select all vertices in Edit mode and duplicate them (⇧ ShiftD). Now scale the new vertices outwards to get a second circle around the original. Leave Edit mode, and a second circle of men will appear (A second row of Magritte’s men.).
Until now all Magritte’s men were facing the camera, ignoring each other. We can get more interesting results using the Rot button next to the DupliVerts button in the Anim settings panel. With this toggle button active, we can rotate the DupliVerted objects according to the normals of the parent object. More precisely, the DupliVerted objects axis are aligned with the normal at the vertex location. Which axis is aligned (X, Y or Z) with the parent mesh normal depends on what is indicated in the TrackX, Y, Z buttons and the UpX, Y, Z buttons top in the Anim settings panel. Trying this with our surrealist buddies, will lead to weird results depending on these settings.
The best way to figure out what will happen is first of all aligning the “base” and “parent” objects’ axis with the World axis. This is done selecting both objects and pressing CtrlA, and click the Apply Size/Rot? menu.
Then make the axis of the base object and the axis and normals in the parent object visible (Show object’s axis to get what you want – in this case, being a circle with no faces, a face must be defined first for the normal to be visible – actually to exist at all). Now select the base object (our Magritte’s man) and play a little with the tracking buttons. Note the different alignment of the axis with the different combinations of UpX, Y, Z and TrackX, Y, Z (Negative Y Axis is aligned to vertex normal (pointing to the circle’s center), Positive Y axis is aligned to normal, Positive X axis is aligned to normal, Positive Z axis is aligned to normal (weird, huh?)).
DupliVerts to Model a Single Object
Very interesting models can be made using DupliVerts and a standard primitive. Starting from a cube in Front view, and extruding a couple of times I have modeled something which looks like a tentacle when SubSurfs are activated (Strange tentacle and SubSurfed version). Then I added an icosphere with 2 subdivisions.
I had to take special care to be sure that the tentacle was located at the sphere center, and that both the tentacle axis and the sphere axis were aligned with the world axis as above (Local reference of the tentacle).
Now, I simply make the icosphere the parent of the tentacle. Select the icosphere alone and made it DupliVert in the Anim settings panel (DupliVerts not rotated).
Press the Rot button to rotate the tentacles (DupliVerts rotated).
Once again to make the tentacle point outwards we have to take a closer look to it’s axis. When applying Rot, Blender will try to align one of the tentacle’s axis with the normal vector at the parent mesh vertex. We didn’t care about the parent circle for Magritte’s men, but here we should care about the sphere, and you will soon notice that it is not rendered. You probably would like to add an extra renderable sphere to complete the model. You can experiment in Edit mode with the tentacle, moving it’s vertices off the center of the sphere, but the object’s center should always be at the sphere’s center in order to get a symmetrical figure. However take care not to scale up or down in one axis in Object mode since it would lead to unpredictable results in the DupliVerted objects when applying the Rot button.
Once you’re done with the model and you are happy with the results, you can select the tentacle and press Ctrl⇧ ShiftA and click on the Make duplis real ? menu to turn your virtual copies into real meshes (Our model complete).
Other duplication methods are listed here.