Surfaces will have to be tessellated into a triangular mesh before it can be shaded. The shading tolerance settings in the control panel controls the accuracy and fineness of the triangulation. A fine tolerance will create more triangles and will create a mesh which fits closely to the underlying surfaces.

The usual method to change the values in Alias is to use the slider associated with the function. However the slider adjustment may be inadequate for small changes. You can always type in value, but then the interactivity is not there. Press ALT + LMB inside the value box and move the mouse. Moving the mouse to the left decreases the value and moving to right increases the value by the least count of the value. ( tip: Pressing ESC key while the cursor is inside the value box will clear the value )

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Failing Trim Surfaces

Sometimes even when Alias shows (by small green locators) that the COS ( Curve on Surface)in a surface forms a closed loop, it fails to trim the surface. The reasons could be because of either one or many of the following.

  • Presence of very small COS segments, usually to the edge of the surface boundary. Identify the small segment, delete it. Now the open region will be indicated by small yellow locators. Extend the COSs, so that they intersect each other. Please be reminded that the history will be deleted by modifying COS.

Most transformations and "Move CV" in control panel can be nudged by arrow keys. For transform > move and transform > scale, the nudge is dependent on the pixel density of the view port. That means the amount of transformation of objects and CVs will depend on the zoom level in the orthographic windows. If the objects are zoomed in, then nudge can be used to change the transformation very minutely. But for Rotation, nudging using the arrow keys will increase or decrease the value by .1 deg.

The "Move CV" command in Control panel has additional controls for locking the directions in X, Y and Z vectors, along with step sizes. This allows us to finely massage the surfaces using nudging in perspective/isometric views, irrespective of the zoom levels. The step size can decreased to .00001 units.


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Regular polygons can be created by using
Curve > Primitive > Cirlce
with "Object Degree" as 1. The "Sections" will then control the number of sides.

Remember to detach the resulting curves at the knot points before using it to create surfaces. Try experimenting  with "Obeject degree" as 1 with surface primitives as well.

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