INTRODUCTION TO GEOMETRIC MODELLING. 20 September 2010. Content. • Introduction • Types of 3D model • 2D vs 3D • Solid M odeling. Introduction. 3D modeling is creating an object or a part which has 3D characteristics and can be viewed 3D
20 September 2010
• Types of 3D model
• 2D vs 3D
• Solid Modeling
• Simply, the object has depth or thickness
• In 2D drafting or drawing, the object is
normally drawn in XY direction.
Object modeled in 3D can be rotated and view from any angle• Generally, more complicated to create and producecompare to 2D
• 3 main types: wireframe, surface and solid
• 3D Wireframe Modeling
– Show the ‘frame’ of the object in lines
– quite similar to 2D, however the object
has 3D characteristics
– has material/texture between the line of
– normally no thickness
– complex/advance curved surface may
– model is made from solid blocks by combining and/or subtracting
– the solid blocks can be created by applying 3D operations on 2D object and/or adding and subtracting primitives
• Solid model consist of volumetric information & surface info of an object
• Surface of the model represent boundary
between outside & inside of the object
• Basic rule – all surfaces must touch another surface
• Several different types of solid modeling
– Primitive modeling
– Constructive solid geometry (CSG)
– Feature-based modeling
• Objects described using basic geometrical forms.
• Common geometric primitives.
• More flexible and powerful than primitive.
• Allow Boolean
Operations: union, difference & intersection
• 3D model is built using series of features, such as hole, slot, square block, etc.
• Each feature can be independent or linked to other feature.
• The geometry of each feature is controlled by modifiable constraints and dimensions.
– 2D cross-section or profile is produced
– Depth is given to the profile
• Generally 4 types
• Cross-section is constant, start – end
a defined axis, 0 – 360 degree
• Cross-section is constant