CG Form - 3D Modelling with Lightwave

Adding Detail, Part 1 - Smooth Shift

This is a useful technique for adding local detail to Sub-Patch objects. Select a Polygon and 'Smooth Shift' without moving the geometry.

With the same Face still selected, use the Stretch Tool in one of the orthogonal viewports, to move the new geometry inwards.

Adding Detail, Part 2 - Bandsaw & Bandsaw Pro

Select one of the newly created Faces and apply the Bandsaw, to add local detail, as shown in this example.

Note: The Bandsaw Tool will only work with 4 Point Polygons and Patches.

Also take a look at the 'Bandsaw Pro' Tool. It allows you to save Presets and gives you a realtime view of the new segments, before you commit.

Construct > Subdivide > Bandsaw
Construct > Utilities > Additional > Bandsaw Pro

Adding Detail, Part 3 - Expand & Reduce Selection

In this example I've selected the innermost Face, then used "}" to expand the selection. I repeated this process to select all five rings of Polygons.

I then moved the selected geometry, down along the Y axis and used "{", to reduce the selection. This process is repeated a few times until only the original Face remains selected.

Display > Selection > Expand
Display > Selection > Contract

Statistics Window - Selecting Geometry

If you've ever converted part of an object to a SubPatch and then realised that you've painted yourself into a corner, because you can no longer simply toggle SubPatch Mode ON/OFF with the TAB key, you'll appreciate the value of being able to select Faces and Patches using the Statistics Window.

It allows you to make a variety of selections and is good for isolating problem areas, such as two Point Poly Lines that won't convert to a SubPatch.

See Also: Depatcher http://www.flay.com/GetDetail.CFM?ID=1374

Modeler > Windows > Statistics (w Key)

Points with Five Vertices

Points that are intersected by 5 Vertices might seem to pinch the surface in Open GL but should render okay without a problem.

Note: It's best to avoid situations where you end up with six or more Vertices intersecting the same Point, as this can disrupt the tension in a Sub-D surface and cause smoothing problems, such as pinching etc.

Points with Six or More Vertices

If you Bevel two adjacent Quads you'll end up with a Point that is intersected by 6 Vertices. This will cause uneven tension and pinching in a SubPatch Surface. Of course the problem gets worse if you Bevel three or more adjacent Quads.

The examples featured here will give you some idea of what's going on and ways of avoiding the problem.

Fixing Cut Quads

Be careful to watch-out for cut Quads. This can sometimes occur when adding Edge Loops with the Knife Tool. If you intersect a Quad through two connecting vertices, it produces a Triangle and a Pentagon.

Triangles are best to be avoided because they create smoothing problems when converting to a Sub-Patch. But more of a problem is the five Point Polygon, which won't convert at all.

To fix this, add a Point to the intersecting Vertices (as shown in the example). Then split the Pentagon, which should leave you with three Quads.

Quicksaw

Take a look at David Iikeda's 'Quicksaw' Lscript. This is a collection of tools that let you slice through a series of selected Polygons. It can even terminate partial edgeloops and works with SubPatch objects.

See Also: Quicksaw http://www.flay.com/GetDetail.cfm?ID=1629

Plugin - Edge Tool

The 'Edge Tool' Plugin lets you split and modify edges for Polygons. The selected Handle also give a percentage readout which is useful as an interactive guide.

See Also: Edge Tool http://www.flay.com/GetDetail.CFM?ID=1355

Re-stitching

Here's two examples of re-stitching techniques, suitable for Sub Division Surfaces.