Editing in Alias for Morph Targets.


Open the file with the Nurbs surfaces that was already converted to polygons.

In this example, I have tried to show the morph target with no modeling of new surfaces. There will be times where new surfaces would have to replace surfaces that are in the morph base. In cases like these, resolution of the base surfaces have to be compatible with the target resolution. This must be determined before any modeling starts on the morph target. As with any morph model, these conditions must be addressed in a strategic manner that cannot be covered effectively in a standard tutorial.

Modeling surfaces in NURBS allows the user a lot of flexibility to use the Alias NURBS editing tools to change surfaces.

Surface editing tools in alias include:

1. Clusters, and the Cluster editor.

2. Proportional Modification.

3. Simple pulling of CV's.

1. Modeling with Clusters

Clusters are groups of points. The reason that you would want to use clusters is that points in a single cluster can have varying intensity from dramatic (100% effect) to negligible (1%). Surfacing the model the way that was shown in the previous example allows us to use clusters with confidence that the surfaces will not pull apart at the seams (because every seam, theoretically, has the identical amount of cv's on each adjoining surface.)

Using Clusters

1. Grab a group of points that you want to move

2. Use the menu option Edit -> New Cluster.

3. Open the Cluster editor. Windows -> Edit -> Clusters...

cluster editor

4. Turn the pick option to "update".

5. You can now adjust the weights og the CV's in the current cluster. Pick some CV's in the cluster, and you will see them highlighted in the cluster editor.

6. Key in a new value in one of the highlighted boxes. The value for all of the highlighted boxes will change.

7. Continue weighing the values in the boxes until the cluster has points with low weight at the edges and high weights on the points in the middle of the cluster.

8. To pick the cluster when you are ready to move it, be sure that no points are currently picked by using Pick -> Nothing. Then use Pick -> Point types -> Clusters to pick the cluster.

9. Move the cluster, you should see a smooth deforming movement along the surface.

10. When you are finished moving the cluster, you need to delete the cluster but keep the transforms. This can be done 2 ways:

10a. Open the Cluster Editor while the cluster is currently picked. Use the Pick -> All option in the Cluster editor. Then use the Edit -> Collapse button to remove all of the point in the cluster. Please note that this will leave the cluster as an empty node in your hierarchy. To delete this node, simply Pick -> Delete Active the cluster node in the SBD window.

10b. Open the Deformation control window (Windows -> Deformation Control). With the cluster picked, select Frame Control -> Collapse. This deletes the cluster and keeps the transforms.

2. Using Xform -> Proportional Mod

Proportional Modification moves a single CV, and allows the surrounding CV's to move in a more gradual way creating a deformation in the surface.

proportional mod

1. Select XForm -> Proportional mod -> options from the menu.

2. Key in the number of CV's in U and V next to the main cv that you want to move. Alias will automatically assign a range of influence to the surrounding CV's that you key in based on the degree that you assign in U and V.

3. Pick the Cv that will act as the center of the deformation.

4. Move the CV. The CV and the surrounding CV's will keep all of the movement that you just applied to it.

3. Pick -> Point Types -> CV, then Xform -> Move

One of the best features of Nurbs surfaces is the ability to pull points and have the surface move in a plastic, deforming manner. This is a simple feature, but very effective. Pick -> Point Types -> CV, then Xform -> Move. Simple.

Final Edited Model

morph target

Final Edited Model Converted to Polygons

morph target polygons

The conversion to polygons should be identical to the method used previously. In this exercise the surface names, order, or resolution have not been changed, only the position of the CV's in the surfaces.