1. Unit 6 3D Modeling Concepts
Sci Vis I Exam Review
Unit 6
3D Modeling Concepts

2. Views PERSPECTIVE Mimics the way the human eye works
Provides “natural” appearance
Parallel lines converge at VANISHING POINTS
Not good for placement or alignment

3. Views ORTHOGRAPHIC Also called PARALLEL PROJECTION
ORTHO means STRAIGHT
2D image of a 3D object
6 Views: top, bottom, front back, left side, right side
Useful for accurate alignment & positioning of objects

4. Viewing in 3D Software PANNING
Moving across a scene (objects don’t move).
ZOOMING
Magnifying the scene (object size doesn’t change).

5. Coordinate Systems 2D Cartesian coordinate system
Horizontal X Axis
Vertical Y Axis
3D coordinate system add Z Axis
Origin = where axes intersect
2D origin is (0,0)
3D origin is (0,0,0)
Coordinates identify locations in space

6. Coordinate Systems Local (User) Coordinate System
Assigns axes to a particular object
World (Global) Coordinate System
Assigns axes to a scene
Relative coordinates
Used to transform an object starting at its current position
Absolute coordinates
Used to transform an object relative to the origin

7. Basic Objects in 3D Modeling Programs
3D Shapes
Sphere
Cube or box
Cylinder
Torus (looks like a donut)
Cone
Plane

8. Basic Objects in 3D Modeling Programs
2D Shapes
Arcs
Ellipses
Circles
Curves
Freehand curves
Polygons (plane figures made with 3 or more straight sides)
Regular polygons (have equal length sides and equal angles)
Splines (curves or polygons that are made of segments that can be manipulated by control points along the curve_

9. Parameters Typical Parameters
Center Point
Radius
Height
Width
Etc.
Parameters affect size, placement, & orientation of objects.

10. Boolean is named after British Mathematician, George Boole.
Modeling Techniques
BOOLEAN
Tools or operations used to create objects by combining, subtracting, or determining common intersections
Union or Addition – combine objects into one new object
Subtract or Difference – remove part of all of an object where objects overlay one another
Intersection – make overlapping parts of objects become the object
Boolean is named after British Mathematician, George Boole.

11. EXTRUSION or SWEEPING (LOFTING)
Modeling Techniques
EXTRUSION or SWEEPING (LOFTING)
Allows you to create a 2D shape and then extend it along a path or curve to form a 3D object
LOFTING is a variation where open or closed curves are spaced parallel to one another and then a surface is created that connects the contours.
These tools are used for things like modeling boat hulls and terrains.

12. Modeling Techniques REVOLVE OR LATHE
Allows you to create 2D shape and then revolve it around an axis.
A lathe is a manufacturing tool used to rotate and shape material by bringing cutting tools against the material while it spins.
Used to model objects such as bowls, bottles, & dishes
Think about putting clay on a spinning pottery wheel and shaping the clay into an object using tools.

13. Modeling Techniques TRANSFORMATIONS OR TRANSFORMS
Actions that scale, rotate, or move objects
Scale changes size or proportions of an object
Rotate tilts or changes direction an object is facing. You rotate about an axis and according to degrees.
Move advances an object from one position to another along one of the axes. Movement may be constrained by a SNAP or GRID setting.

14. Modifies an existing shape.
Modeling Techniques
DEFORMATION
Modifies an existing shape.
Mimic the process of working with a piece of clay.
Examples are taper, bend, twist, smooth, & stretch.

15. Other Modeling Techniques
COPY or CLONE: allow selected objects to be reproduced in their exact size & form
MIRROR: allow selected shapes to be copied or flipped about a defined center

16. VIEWING TOOLS
WIREFRAME: draws objects as edges and vertices, simplest viewpoint
SOLID: allows the object to appear as a solid
OTHER: Transparent, Transparent Wireframe, etc.

17. VIEW NAVIGATION TOOLS ZOOM: magnification
ROTATE: object remains in it’s position within scene while you rotate your point of view
PANNING (Eye Move): allows you to drag the scene within the viewpoint (window) without changing the positions of objects.

18. EXPORTING
Create objects and scenes in one software package and use it in another software package.
File, Save As in the existing software package to save to the file format of the intended software package.