Computer Graphics for GM - Introduction1.pdf

GEOMETRIC MODELLING 1  Geometric Modelling - Introduction Geometric Modelling is the computer/software generated mathematical representation of an object’s geometry. It includes both graphical and non-graphical information. This information is store...

GEOMETRIC MODELLING 1  Geometric Modelling - Introduction Geometric Modelling is the computer/software generated mathematical representation of an object’s geometry. It includes both graphical and non-graphical information. This information is stored in a database and displayed as a picture. It is then possible to edit and analyze the model in different ways. 2 Geometric Modelling - Introduction 3 Geometric Modelling - Introduction 4 Geometric Modelling - Introduction 5  Geometric Modelling - Introduction Geometry deals with quantitative properties of space, such as distance and curvature on manifolds. Topology deals with more qualitative properties of space, namely those that remain unchanged under bending and stretching. Geometry focuses on measuring and quantifying the properties. Topology is concerned with the relationships between objects when distance and measurement are not 6 considered. Geometric Modelling - Introduction 7  Geometric Modelling - Introduction Representation of Geometric Models Two-Dimensional or 2D: It projects a two-dimensional view and is used for flat objects. Three-Dimensional or 3D: This representation permits complete three-dimensional viewing of the model with intricate geometry. The leading process of geometric modeling in 3D is Solid modeling. 8  Geometric Modelling - Introduction Construction of a Geometric model Constructing a geometric model in CAD involves using a 3D computer program to describe geometric relationships and the physical extent of a component. The models may also contain material properties and other attributes of the element, such as the mass, volume of the component. Many CAD programs can calculate a component’s mass properties and evaluate its other physical properties. These capabilities may be crucial for flexible and adaptive manufacturing lines. 9  Geometric Modelling - Introduction Geometric Model Presentation There are two main types of presentations in geometric modeling. The classical presentation or Nonparametric modelling of geometric objects consists of geometric point sets that define the boundaries. On the other hand, modern geometric modeling or Parametric modelling, which uses parametric families of point sets. Parametric families are defined using geometric operation graphs, features, and constraints. In both cases, a user interacts with an example object from the family. It may also be a surface, a volume, or a solid. With the help of geometric modeling applications, key elements can be created, transformed, and integrated into the desired shape. In addition to these, geometric modeling can incorporate other design and manufacturing aspects like Computer- aided engineering (CAE), Computer aided manufacturing (CAM), which are the central component of the manufacturing process. 10  Geometric Modelling - Introduction Requirements for developing Geometric Modelling The cross-section, hidden lines, and dimensions are needed for Graphical Visualization. Interchangeable manufacturing tolerance analysis is required while inspecting parts. There should also be properties and geometrical evaluations in terms of Area, Volume, and property evaluation in terms of Weight, Density, etc. Need for carrying out FEA/FEM and Kinematic analysis. Parts classification, planning, toolpath generation etc., in manufacturing. 11 Computer Graphics - Introduction 12  Computer Graphics - Introduction What is Computer Graphics ? 13 Geometric Modelling - Introduction 14 Geometric Modelling - Introduction 15 Geometric Modelling - Introduction 16 Geometric Modelling - Introduction 17 Geometric Modelling - Introduction 18 Geometric Modelling - Introduction 19 Geometric Modelling - Introduction 20 Geometric Modelling - Introduction 21 Computer Graphics - Introduction 22 Computer Graphics - Introduction 23 Computer Graphics - Introduction 24 Computer Graphics - Introduction 25 Computer Graphics - Introduction 27 Computer Graphics - Introduction Types of Computer Graphics 28 Computer Graphics - Introduction 29 Computer Graphics - Introduction 30 Computer Graphics - Introduction 31  Computer Graphics - Introduction The Principal Components of Interactive Computer Graphics 32  Computer Graphics - Introduction The Principal Components of Interactive Computer Graphics The following elements are the basic components of Interactive Computer Graphics: Input device: users are able to interact with graphics using input devices such as keyboard, mouse, touchscreen, and game controller. Display device: a display device like a monitor or a screen is needed for presenting the graphics to users Graphic pipeline: a set of stages such as rasterization, geometric processing, output merging, and pixel shading, used for rendering graphical data Rendering engine: it creates the final output by performing the necessary operations to convert the objects’ descriptions into rasterized images 33  Computer Graphics - Introduction Graphic User Interface (GPU): it helps users to interact with the system. Buttons, menus, sliders, and other UI elements are used to manipulate objects, control the graphics app, and change settings Interaction technique: it includes actions such as dragging, clicking, and rotating objects Application logic: the algorithms that control the behavior of the Interactive system by determining the way that objects interact together and the way the graphic systems react and behave in different situations 34 Computer Graphics - Introduction Configuration of Graphics system 35  Computer Graphics - Introduction Software Configuration of Graphics system 36  Computer Graphics - Introduction Hardware Configuration of Graphics system Minimum computer specifications: These specifications are minimums for students taking a graphic design course as an elective or for enrichment. These specifications do not apply to those enrolled in GD 110, GD 260, or GD 270 and are not recommended benchmarks for students enrolled in a Graphic Design degree program. Windows ▪ Windows® 10 (64-bit) or higher ▪ Multicore Intel processor with 64-bit support or AMD Athlon 64® processor that supports SSE 4.2 or later ▪ 8 GB of RAM or more ▪ 15 GB free hard drive space or more GPU with DirectX 12 support and supports OpenGL version 4.0 or greater ▪ Internet connection access 37 Computer Graphics - Introduction 38 Computer Graphics - Introduction 39 Computer Graphics - Introduction 40 Computer Graphics - Introduction 41 Computer Graphics - Introduction 42 Computer Graphics – Graphics Standards 43 Computer Graphics – Graphics Standards 44 Computer Graphics – Graphics Standards 45 Computer Graphics – Graphics Standards 46 Computer Graphics – Graphics Standards 47 Computer Graphics – Graphics Standards 48 Computer Graphics – Graphics Standards 49 Computer Graphics – Graphics Standards 50 Computer Graphics – Graphics Standards 51 Computer Graphics – Graphics Standards 52 Computer Graphics – Graphics Standards 53 Computer Graphics – Graphics Standards 54  Computer Graphics – Graphics Standards Initial Graphics Exchange Specification (IGES ) is a neutral file format designed to transfer 2D and 3D drawing data between dissimilar CAD systems. It is an ASCII-based textual format 55 Computer Graphics – Graphics Standards 56 Computer Graphics – Graphics Standards 57 Computer Graphics – Graphics Standards 58 Computer Graphics – Graphics Standards 59 Computer Graphics – Graphics Standards 60 Computer Graphics – Graphics Standards 61 Computer Graphics – Graphics Standards 62 Computer Graphics – Graphics Standards 63 Computer Graphics – Graphics Standards 64  Computer Graphics – Networking HARDWARE INTEGRATION AND NETWORKING in GEOMETRIC MODELLING Networking : The joining of a number of computing systems through a cable, optical fibers etc. Few types of networks are LAN (Local Area Network) A Local Area Network (LAN) is a network that connects computers and devices in a limited geographical area such as a home, school, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Wired LANs are most likely based on Ethernet technology. MAN (Metropolitan Area Network) A Metropolitan Area Network (MAN) refers to the networking of computers with in a city. WAN (Wide Area Network) A wide area network (WAN) is a computer network that covers a large geographic area across the cities and countries. WAN uses a communications channel that combines many types of media such as telephone lines, 65 cables, and air waves.  Computer Graphics – Networking LAN Configurations for Geometric Modelling The four most popular LAN configurations available are: 1. STAR 2. RING 3. BUS 4. Combined STAR and BUS STAR LAN configuration: It consists of a central computer (server) to which several workstations and central peripherals are attached. This configuration is suited for workstations supported by mainframes / super computers. The advantage is that the Star-LAN contains a central database that is accessible by all users. The disadvantage is that each time data has to be saved or accessed from central 68 computer.  Computer Graphics – Networking RING LAN Configuration This configuration is well suited when devices are mostly similar such as stand-alone workstations. The databases or files on one workstation can be shared by others in the network. BUS LAN Configuration It is an open loop system. It may take the form of bus / branched / tree systems. It is suited when dissimilar devices are to be connected. Ethernet system 69  Computer Graphics – Networking Combined STAR- BUS LAN Configuration Central mainframe serves as the host for the control of the star LAN and it is generally used for the control of central devices like plotters. Workstations are connected to the mainframe in star format. The workstations can also communicate with one another over an Ethernet bus LAN. It is a high speed communication network. 70  Computer Graphics – Database Management Database management in Geometric Modelling Formally, a database is defined as an organized collection of graphics and non-graphics data stored on secondary storage in the computer. It is viewed as the art of storing or the implementation of data structure into the computer. The objective of a database is to collect and maintain data in a central storage so that it will be available for operations and decision -making. Advantages Eliminates redundancy Enforces standards Applies security restrictions Maintains Integrity Balances conflicting requirements 71  Computer Graphics – Networking Data structure in Geometric Modelling : It is defined as a set of data items / elements related to each other by a set of relations. It can also be defined as a scheme, logic or a sequence of steps developed to achieve a certain graphics, non-graphics entities on the display An object can be developed when these relations are applied to the elements of the set. Consider the example shown : Three different types of data structures have been identified to construct the object. These structures are based on 72 edges, vertices, or blocks  Computer Graphics – Networking Data structure based on edges As an example, 1, A & B in Fig. b indicates that vertex 1 is shared by edges A and B. Data structure based on set of vertices In Fig. c, A, 1 & 4 indicates that edge A has the two vertices 1 and 4. Data structure based on blocks In Fig. d, B1 and B2 are the blocks defined by the edges and vertices while the set operator is Union, which is used to join the blocks B1 and B2. 73  Computer Graphics – Networking Types of Database: 1. Relational database 2. Hierarchical database 3. Network Database 4. Object oriented database 1) Relation database: Related data are stored in table, called relations. The object is represented by the 3 relations POINT, LINE/CURVE & SURFACE. The data structure determines which relations are to be entered by the user and which are to be calculated automatically. Disadvantage: It requires lot of sorting, which will slow down the system response to user commands. 74  Computer Graphics – Networking 2) Hierarchical database: In this model, data represented by the tree structure. The top of the tree is known as root. In this type of database, four levels are required to represent the object completely. Drawback: Asymmetry of the tree structure, forces the database programmers to devote more time & effort to solving problems. 75  Computer Graphics – Networking 3) Network database: This approach permits modeling of many to many correspondence more directly than the hierarchical approach. Disadvantage: It is complex both in the database structure as well as its programming. 76  Computer Graphics – Networking 4) Object oriented database: Geometric Modelling applications require object oriented accessing and manipulation Designed objects can be directly stored in to & retrieved from the database instead of individual records in files. These design objects also form the basis for ensuring database integrity upon making changes to the component objects. 77 Computer Graphics – Coordinate Systems 78 Computer Graphics – 2D Coordinate Systems 79  Computer Graphics – 2D Co ordinate Systems Absolute coordinate system: 80  Computer Graphics – 2D Co ordinate Systems Relative / Incremental coordinate system: To indicate that the coordinate being entered is relative, the @ symbol must precede the coordinate value. For example, @2,6, which means ' from the lastpoint go 2 units in the positive X and 6 units in the positive Y '. 81  Computer Graphics – 2D Co ordinate Systems Polar /Angular coordinate system: To specify relative coordinates, precede the coordinate values with an @ sign. For example, entering @1