Blend Curves and Blending Surfaces An Introduction to

Main Surface Blends A smooth, continuous surface. . . will be modeled from surface

Features and Complex Forms Sculpted features can be added to a design and blended in. © 2009 Autodesk Complex topologies that cannot be sculpted from a single surface can be constructed from blended surfaces. 3

Workflow Example Create a licence plate recess using a bi-rail surface. Create the main surfaces. © 2009 Autodesk Trim a gap for the blended surface. Use curves to design the character of the blend. 4 Create a surface with continuity.

Curve to Surface Continuity Object Edit>Align If a surface edge, isoparm, or curve-on-surface is selected as the master, the CVs of the input curve will align to the U or V direction of the line. If the curve doesn’t meet a line, then the ‘vector’ option should be used. Master Input The CVs will move only in the direction specified in the vector options to achieve the requested continuity. © 2009 Autodesk 5

Surface Tools and Continuity Tangent Continuity Only Tangent and Curvature Continuity: Limited Control Tangent and Curvature Continuity: Low-Quality Surface Tangent and Curvature Continuity: Full Control The rail and square surfaces have two attributes that make them suitable for creating blend surfaces: continuity and rebuild. © 2009 Autodesk 6

Continuity and Rebuild Continuity allows you to set the continuity separately for each edge.

Implied Tangent Try to keep tangency with an implied surface that shares this edge. The implied surface is the surface that would be created by mirroring the new surface. With Position, there is a small tangency break between the mirrored surfaces. © 2009 Autodesk With Implied Tangency, the surface is held tangent to the mirrored surface along its length. 8

Blend Surface Errors Continuity Failure If a blend surface fails, use the Continuity Check within the Bi-rail and Square tools to get more information. Use the Evaluate>Surface Continuity tool to check other edges to locate the source of the problem. © 2009 Autodesk 9

Exercises EX 1 -Square-rebuild. wire EX 2 -Bi-rail-rebuild. wire EX 3 -N-sided. wire EX

Blend Curves What Is a Blend Curve? A blend curve is a normal NURBS curve with extra controls called ‘blend points’. Blend Curve Attributes Blend points are ‘sticky’—if placed on an existing curve or surface, they become associated and stay attached. Blend points lie on the curve (unlike CVs) and can be used successfully to shape the curve. Blend curves are automatically created at G 2 (curvature) continuity when associated with an existing surface. Blend curve are modified using manipulators, not by moving CVs directly. © 2009 Autodesk 11

Blend Curve Tools Blend Curve Toolbox Pick>Blend Point Control Panel>Display Clicking on the Blend Curve icon opens a separate toolbox for working with blend curves. Use Pick>Blend Point and Transform>Move to modify the blend curve shape. Use Control Panel>Display to turn on and off blend points. Golden Rule! Turn on the CVs for blend curves to understand the CV structure of the curve and to help diagnose problems. © 2009 Autodesk 12

Blend Curve Basic Tools Create Blend Curve Blend Point Associativity Click to place blend points. If a blend point has been associated with an object, then, when you pick and move the point, it will stay attached. If you click on a curve or surface, the blend point becomes associated to the object and will stay attached as the object is moved. The Blend Point icon changes if the point is associated or free. Blend Curve Add Points Select the tool, and then click on a blend curve to add a blend point. To Delete a Blend Point Use Pick>Blend Point and then delete. © 2009 Autodesk 13

Blend Curve Continuity Blend Curve Edit Use to display and adjust the continuity locator. Click on the green dotted lines to align to the surface U and V. Green Lines: Surface Alignment Blue Arrows: Direction Constraint Click and drag on the square and circle to adjust the CV positions and the shape. Tangency CV Adjustment (Square) © 2009 Autodesk Curvature CV Adjustment Circle 14

Tools for a Selected Curve Blend Curve Degree Blend curves will default to degree 5. To change the degree, pick the curve and select the required degree. Blend Curve Construction History The blend curve will update as its associated objects are modified. © 2009 Autodesk 15

Tools for a Selected Blend Point Pick>Point Types>Blend Point Continuity Pick the blend point and choose the continuity required. Continuity defaults to G 2 (curvature) when associated to a surface. Blend Constraint Interpolation Changes the locator so that you can align the curve to the XYZ axes or to the surface parameterization. Blend Constraint Direction Switch to point ray when you need to change the direction of a blend point. © 2009 Autodesk 16 Dissociate Blend Constraint Makes a blend point free.