Lecture 7. Neutral File. Lecture 7 1

Transcription

1 Lecture 7 Neutral File Lecture 7 1

2 What is neutral file? Without neutral file, we requires 2 N number of translator for N numbers of software. Translator Computer Computer Computer Computer Computer Neutral File Computer Computer Computer (a) (b) Lecture 7 2

3 What need to transfer? Shape data: both geometric and topological information, part or form features. Fonts, color, annotation are considered part of the geometric information. Non-shape data: graphics data such as shaded images, and model global data as measuring units of the database and the resolution of storing the database numerical values. Design data: information that designers generate from geometric models for analysis purposes. Mass property and finite element mesh data belong to this type of data. Manufacturing data: information as tooling, NC tool paths, tolerancing, process planning, tool design, and bill of materials (BOM). Lecture 7 3

4 Who develop neutral file Standard institutions IGES (American Code for Information Interchange), STEP (Standard for the Exchange of Product Model Data) CAD software DXF (Drawing Interchange File Format), ACIS (Alan, Charles, Ian System) Specific application Lithography, VRML (Virtual Reality Modeling Language), VDAFS (Vereinung Deutsche Automobilindustrie Flachen Schnittstelle), Graphic (bmp, tiff, metafile etc) Lecture 7 4

5 IGES (*.igs) Refer to the attachment for sample file Divided into 5 sections: START: indicated by letter S on the first of the file GLOBAL: indicated by letter G. It shows the properties of the file (file name, system that creates the file, units and precision). Normally comprising of 5 lines (G1 to G5) DIRECTORY ENTRY: shown by letter D. Show all the non geometry properties (color, line type, transformation matrices) PARAMETER DATA: shown by letter P. Show all the geometrical properties of the entities. TERMINATE: ends of the file and shown by letter T Lecture 7 5

6 START GLOBAL DIRECTORY ENTRY PARAMETER DATA TERMINATOR Lecture 7 6

7 GLOBAL Parameter Delimiter Character = "," Record Delimiter Character = ";" Product ID from Sender = "{Unknown}" File Name = "line circle.igs" System ID = "Autodesk DirectConnect Pre-processor Version = " " Number of Bits for Integers = 32 Single Precision Magnitude = 38 Single Precision Significance = 6 Double Precision Magnitude = 308 Double Precision Significance = 15 Product ID for Receiver = "{Unknown}" Model Space Scale = Unit Flag = 1 - Inches Units = "INCH" Maximum Number of Line Weights = 1 Size of Maximum Line Width = 0.01 Date & Time Stamp = " " Minimum User-intended Resolution = Approximate Maximum Coordinate = Name of Author = " jamaltaib" Author's Organization = "{Unknown}" IGES Version Number = 11 Drafting Standard Code = 0 Model Creation/Change Date = " " Lecture 7 7

8 DIRECTORY ENTRY 2 lines for each entity 100 Circular arc 108 Plane 110 Line 116 point 124 Transformation matrix Line1 Field 1: Entity type (100 = Line) Line 2 Field 2: Pointer will refer to parameter data line (3 refer to Field 11: Entity type line 3 in parameter data) Field 12: Line weight 0 to max Field 3: Pointer to D section (default 0) Field 13: Color number: 0-8. Negative number refers to a Field 4: Line font pattern Color Definition Field 5: Level Field 14: No. of lines in P for this entity Field 6: Pointer to section D line of view entity Field 15: Form number for entities having more than one Field 7: Pointer to section D entry of transformation matrix definition (Line 3: 124) Field 16: Not used Field 8: Pointer to section D entry of label (not applicable Field 17: Not used line) Field 18: Entity label, up to 8 chars. Field 9: Status. 4x2-digit values to form 8-digit number, no Field 19: Entity subscript number spaces. Field 20: Line number within D section (6, the second line Field 10: Line number within D section. (5, the first line the must be an even number) number must be odd) Lecture 7 8

9 PARAMETER DATA The parameter is based on the entity For example, Circle: 10 parameters which are entity type, x, y, and z of center point, and radius. Line : 7 parameters, entity number follows the x, y, and z of the start and end point Lecture 7 9

10 IGES: con t B-Reps topology and geometry relationship Topology Solid Shell Face Loop Edge Vertex Geometry Surface Curve Node Lecture 7 10

11 ACIS (*.sat) ACIS is acronym to Alan, Charles, Ian System. ACIS file is indicated in.sat file name and it is formatted according to ASCII code. ACIS has a number of reserved characters to indicate the information. The reserved characters are $ :indicates a pointer definition. # :terminates an entity : starts of string record Lecture 7 11

12 ACIS (*.sat) Refer to the attachment for sample file Divided into 4 sections START:starts with array of number ( ) FILE DATA: information on the software generate the file, date, precision etc ENTITY DATA: topology and geometry data are stored here. Every line starts with structure names and ends with # END: remarks the end of the file by End-of- ACIS-data statement. Lecture 7 12

13 HEADER: ACIS (*.sat) First line First Integer: An encoded version number (22.00). Second Integer: The total number of saved data records, or zero. If zero, then an end mark is required. Third Integer: A count of the number of entities in the original entity list that were saved to the part file. Forth Integer: The least significant bit of this number is used to indicate whether or not history has been saved in this save file. Lecture 7 13

14 HEADER: ACIS (*.sat) Second line First Integer: String length for the product string: 15. Second String: ID for the product which produced the file: SolidWorks Third Integer: String length for the ACIS version string: 12. Fourth String: ACIS version which produced the file: ACIS 22.0 NT. Fifth Integer: length for the date string: 24. Sixth String: Date file produced Wed Mar 19 10:51: Lecture 7 14

15 DATA: ACIS (*.sat) First data must data for body, and the following data will be randomly stated Each entity record consists of a sequence number, an entity type identifier, the entity data, and a terminator. Entity type identifier is unique string such body, lump, etc. The data sections ends with End of Sec. 15

16 ACIS: con t Topology and geometry relationship Topology Geometry Body Lump Shell Face Surface Loop Coedge Edge Curve Vertex Node Lecture 7 16

17 STEP (*.step) Developed by International Standard Organization (ISO 10303) STEP is Standard Exchange Protocol The aim of STEP is to allow exchange of data between different platforms without human intervention and integrate of data from different platforms. STEP is in fact computer interpretable representation of the data. Lecture 7 17

18 STEP (*.step) STEP is divided by its application protocol (AP). Examples of AP AP201: Drawing AP 203: 3D designs of mechanical parts and assemblies AP 214: Automotive mechanical design processes AP STEP numeric controllers AP 240, Process plans for machined products Lecture 7 18

19 Refer to the attachment for sample file STEP (*.step) Divided into 2 section HEADER: starts with HEADER; and ends with ENDSEC;. Purpose: propose to show the file type, file name and software used. DATA: starts with DATA; and ends with ENDSEC;. Comprises of the topological and geometrical data of the objects. Lecture 7 19

20 HEADER : STEP (*.step) File description: STEP AP203 Implementation level: 1 File name: 2 step 203 fea.step Time: T07: 09:14 Author: (' '), Organization: (' '), Preprocessor version: 'SwSTEP 2.0' Originating_system: 'Solid Work 2013', Authorization: (' '); Lecture 7 20

21 SPECIFIC APPS : Stereo lithography Stereo Lithography file format has.stl extension. Solid model has been represented as a list of triangulated surface comprises of loop of three vertices. This file format has been widely in rapid prototyping machine and 3D printer. Lecture 7 21

22 SPECIFIC APPS : Stereo lithography Lecture 7 22

23 SPECIFIC APPS : Stereo lithography Stereo Lithography file format has.stl extension. Solid model has been represented as a list of triangulated surface comprises of loop of three vertices. This file format has been widely in rapid prototyping machine and 3D printer. Lecture 7 23

24 SPECIFIC APPS : VRML Virtual Realty Modelling Lang. VRML has.wrl file extension. Store the rendering information of the model. Widely been used in www. Lecture 7 24

25 SPECIFIC APPS : VRML Lecture 7 25

26 How to comprehend neutral file Buy the related documents. Model known entities and save the entities to respective neutral file and compare the known entities with the data in the neutral file. Note: mostly all neutral file using ASCII code and therefore can be read using most word processing and even notepad. Case Study: ACIS and STEP Cylinder Radius: 20 Height: 20 Center point of bottom plane face: (0,0) Extrusion: Z axis Lecture 7 26

27 Product definition: ACIS Line 12: Loop information Top topology: line 3 face Bottom topology: line 18 coedge Refer to the attachment for sample file Line 7: surface information Surface: Cone Reference Vertex: (0,0,0) Normal vector: (0,0,1) Radius: 20 Lecture 7 27

28 Product definition: STEP Refer to the attachment for sample file Edge List of curve : start node (20, 0, 0) 133: end node (20, 0, 20) 137: Entity type : line Length : 20, vector (0, 0, 1) and reference node (20, 0, 0) : start node (20, 0 20) 150: end node (-20, 0, 20) 177: Entity type: circle Radius: 20, Reference coordinate( 0, 0 20), normal vector (0, 0, -1) and reference vector (1, 0, 0) : start node (-20, 0, 20) 141: end node (-20, 0, 0) 154: entity type: line Length 20, vector (0, 0, -1) and reference node (-20, 0, 20) : start node (-20, 0, 0) 131: end node (20, 0, 0) 185: : entity type : circle Radius: 20, reference node ( 0, 0, 0), normal vector (0, 0, 1) and reference vector (1, 0, 0) Lecture 7 28

29 Product definition: STEP (con t) (a) (b) Lecture 7 29

30 CASE STUDY: AP 203 and A P214 INPUT Lecture 7 30

31 CASE STUDY: AP 203 and A P214 AP 203 AP 214 Lecture 7 31

32 CASE STUDY: AP 203 and A P214 INPUT Lecture 7 32

33 CASE STUDY: AP 203 and A P214 AP 203 AP 214 Lecture 7 33

34 CASE STUDY: FEATURE RECOGNITION INPUT OUTPUT Lecture 7 34

35 What do you think of neutral file?

36 Homework: Neutral File You have to set the aim of the study in the neutral file For example: i) To study of the level of complexity of the part and the accuracy of the transfer. ii) To study of the type of file transfer based on the complexity of the part Submission: You have to submit one report on the findings of your study. In the report, state - Objective of the study - Scope of the study - Findings with examples - Your opinion on the neutrality of the file.