INTRODUCTION TO CAD

CAD is a process of preparing a drawing of an object on the screen of a computer. There are various
types of drawings in different fields of engineering and sciences. In the fields of mechanical or
aeronautical engineering, the drawings of machine components and the layouts of them are prepared. In
the field of civil engineering, plans and layouts of the buildings are prepared. In the field of electrical
engineering, the layouts of power distribution system are prepared. In all fields of engineering use of
computer is made for drawing and drafting.

The use of CAD process provides enhanced graphics capabilities which allows any designerto

Conceptualize his ideas

Modify the design very easily
Perform animation
Make design calculations
Use colors, fonts and other aesthetic features.

REASONS FOR IMPLEMENTING A CAD SYSTEM

1. Increases the productivity of the designer: CAD improves the productivity of the designer to
visualize the product and its component, parts and reduces the time required in synthesizing,
analyzing and documenting the design

2. Improves the quality of the design: CAD system improves the quality of the design. A CAD system
permits a more detailed engineering analysis and a larger number of design alternatives can be
investigated. The design errors are also reduced because of the greater accuracy provided by the
system

3. Improves communication: It improves the communication in design. The use of a CAD system
provides better engineering drawings, more standardization in the drawing, better documentation of the
design, few drawing errors and legibility.

4. Create data base for manufacturing: In the process of creating the documentation for these products, much
of the required data base to manufacture the products is also created.

5.Improves the efficiency of the design: It improves the efficiency of the design process and the wastage at
the design stage can be reduced.

APPLICATION OF CAD:

There are various processes which can be performed by use of computer in the drafting process.

1. Automated drafting: This involves the creation of hard copy engineering drawings directly from CAD
data base. Drafting also includes features like automatic dimensioning, generation of cross – hatched areas,
scaling of the drawing and the capability to develop sectional views and enlarged views in detail. It has
ability to perform transformations of images and prepare 3D drawings like isometric views, perspective
views etc.,
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2. Geometric modeling: concerned with the computer compatible mathematical description of the
geometry of an object. The mathematical description allows the image of an object to be displayed and
manipulated on a graphics terminal through signals from the CPU of the CAD system. The software that
provides geometric modeling capabilities must be designed for efficient use both by computer and the human
designer.

BENEFITS OF CAD:

The implementation of the CAD system provides variety of benefits to the industries in design and
production as given below:

1. Improved productivity in drafting

2. Shorter preparation time for drawing
3. Reduced man power requirement
4. Customer modifications in drawing are easier
5. More efficient operation in drafting
6. Low wastage in drafting
7. Minimized transcription errors in drawing
8. Improved accuracy of drawing
9. Assistance in preparation of documentation
10. Better designs can be evolved
11. Revisions are possible
12. Colors can be used to customize the product
13. Production of orthographic projections with dimensions and tolerances

INTRODUCTION TO CAD
.
AUTO CAD
Auto CAD package is suitable for accurate and perfect drawings of engineering designs. The drawing of
machine parts, isometric views and assembly drawings are possible in AutoCAD. The package is suitable
for 2D and 3D drawings.

AutoCAD is a Computer Aided Design (CAD) program used by just about every Engineering and Design
office in the world. Although there are alternative CAD packages, AutoCAD is so far the most widely
used system. Autodesk's AutoCAD is the industry leader in CAD packages, Used by Civil Engineers,
Architects, Mechanical and Electrical Engineers, Aeronautical Engineers plus many other disciplines.
There have been several versions of AutoCAD over the years, with each new version introducing new and
more powerful features than its predecessor. Any courses, whether through community colleges or online
universities. Accurate, scale drawings can be created and published using AutoCAD powerful features. 3D
'models' can also be created giving the designer absolute control

over the design from start to finish. The computerized model can be viewed through a 360º angle, and
even 'rendered' with a texture on screen to give an idea of the finished product.

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BASIC COMMANDS USED IN CAD
LINE: -A Line is a straight path joining two points.
Click Home tab Draw panel Line. Find
Specify the start point and end point of the line segment. Continue specifying additional line
segments.

POLYLINE:- A polyline is a connected sequence of line segments created as a single object. You can
create straight line segments, arc segments, or a combination of the two.

CIRCLE: - A round plane figure whose boundary (the circumference) consists of points equidistant from a
fixed point.
THE CIRCLE COMMANDS PROVIDES 6 WAYS TO DRAW A CIRCLE.
1. CENTER,RADIUS
2. CENTR,DIAMETER
3. 2-POINT(2P)
4. 3-PONIT (3P)
5. TANGENT-TANGENT-RADIUS
6. TANGENT-TANGENT-TANGENT

ARC:- Creates an arc.

To create an arc, you can specify combinations of center, endpoint, start point, radius, angle, chord
length, and direction values. Arcs are drawn in a counterclockwise direction by default. Hold down
the Ctrl key as you drag to draw in a clockwise direction.
THERE ARE 7 METHODS TO DRAW ARC
1. Three points method
2. Start point-center point- end point.
3. Start point-center point- length of chord.
4. Start point-end point- angle.
5. Start point-end point- radius.
6. Start point-center point- angle.
7. Start point-end point- direction.

POLYGON:-
A plane figure with at least three straight sides and angles, and typically five or more.
Draw a Polygon

Click Home tab Draw panel Polygon. Find

Enter the number of sides.

Specify the center point of polygon.

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 Do one of the following:
Enter i to specify a polygon inscribed within a circle.
Enter c to specify a polygon circumscribed about a circle.
ELLIPSE :- A regular oval shape, traced by a point moving in a plane so that the sum of its
distances from two other points (the foci) is constant, or resulting when a cone is cut by an oblique plane
which doesnot intersect the base.
The shape of an ellipse is determined by two axes that define its length and width.

MODIFYING COMMANDS:

ERASE: Removes objects from a drawing.

To erase the last object drawn, p to erase the previous selection set, or ALL To erase all objects.

COPY : Copies objects a specified distance in a specified direction.

MOVE: Moves objects a specified distance in a specified direction. Use Coordinates, grid snaps, object
snaps, and other tools to move objects with Precision.

MIRROR: Creates a mirrored copy of selected objects. You can create objects that represent half of a
drawing, select them, and mirror them across a Specified line to create the other half.

OFFSET: Creates concentric circles, parallel lines, and parallel curves. You can offset an object at a
specified distance or through a point. After you offset objects, you can trim and extend them as an efficient
method to create Drawings containing many parallel lines and curves.

ARRAY: Creates copies of objects arranged in a pattern. Polar and rectangular

TRIM: Trims objects to meet the edges of other objects

EXTEND: Extends objects to meet the edges of other objects. To extend Objects, first select the boundaries.
Then press Enter and select the objects that you want to extend.

FILLET Rounds and fillets the edges of objects

VARIOUS COORDINATES SYSTEMS USED IN AUTOCAD

There are 3 coordinates’ system methods to draw a figure of object using auto CAD:

1. ABSOLUTE COORDINATE SYSTEM: - This system is used when the coordinates of end points of line
are known.

2. RELATIVE COORDINATES SYSTEM:- This system is used when distance of a point with respect to the
previous point is known.
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This system is based on the last point located. The distance along the X and Y axis are measured with
reference to the previous point. The syntax is @X,Y.

3. RELATIVE POLAR COORDINATES SYSTEM:- This system uses a distance and an angle with
reference to the initial point to locate a point. The angle is measured in anticlockwise direction, taking
0 deg to ward right. Its syntax is @ direct distance < angle.

CAD SOFTWARES
1. CATIA
2. UNI-GRAPHICS
3. SOLID-EDGE
4. ANYSIS
5. PRO-E
6. CRIEO
7. FOCUS 360
8. AUTOCAD
9. SOLIDWORKS
10. ONSHAPE
11. DRAFTSIGHT
12. TEAMCENTER
13. OPENSCAD
14. SIEMENS NX

LIST OF AUTOCAD COMMANDS

Here the concerned area is to tell the list of AutoCAD commands to use in this software

1. L Command- This is the most common command used in this software. To use this command user has
to type L on the taskbar provided at the bottom of the screen and then press enter. User has to define the
starting point and endpoint. It will allow him to draw a simple line. The line can also be defined in the
polar firm by providing angle and radius.
2. C command- To use this user has to type C in the taskbar. It will allow the user to draw a circle by
providing a point and radius.
3. PL command- This will make Poly Line in your drawing. The endpoint of a first line will act as a
starting of the second line and so on.
4. REC command- This command is used to draw a rectangle in Auto CAD. To specify the length, breadth
of a rectangle user has to specify a starting point and a point diagonally opposite to the first point.
5. POL command- This will allow the user to construct a polygon. To use this command user has to
specify the number of edges, the center of the polygon and also tell that the circle will be inscribed inside
or circumscribed outside the polygon.
6. ARC command- This will allow the user to create an arc. The software will ask the user about the
starting point/center of the arc with 2 endpoints.
7. CO command- This is used to copy on the object. To use this user has to select an object and paste it at
its desired location.

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8. AL command- This command allows the user to align an object with another object. To use this one has
to specify the source and destination point of the object. The source point is the location of the object
which is to align and the destination point is the desired location. Users can also scale the source objects
with respect to the destination object.
9. AR command- This command allows us to create an array of objects. Users can create an array
according to the desired profile.
10. CHA command- This will create a chamfer between 2 non-parallel lines.
11. E command- This will erase the selected object from the Auto CAD window.
12. EX command- This will extend the object about the profile. To use this one has to select the object to be
extended and then after pressing enter one has select object up to which it has to be extended.
13. TR command- This will trim the object. To use this one has to select the object to be trimmed and then
press enter. After that one has to select the object about which the object has to trim.
14. RO command- This command will rotate the object about the specified point. To use this one has to
select the object to be rotated and then select a base point about which object is to be rotated.
15. O command- This command will offset the object up to the desired distance. To use this user has to
select the object to offset and then specify the distance up to which is to be offset.
16. J command- This command will allow objects to join together.
17. M command- This command will allow moving the object. To use this one has to select the object to be
moved and then specify the point about which it has to move.
18. JPGOUT command- This command will save your Auto CAD drawing in .jpeg format.
19. ME command- This command will measure your concern object dimensions.
20. COL command- This command will open a dialogue box for choosing the desired color.
21. DIV command- This command will divide your object into different segments. For example, a line is to
be divided into parts
22. F command- This command will provide a fillet/arc between 2 intersecting lines. To use this one has to
select 2 intersecting lines and then press enter.
23. H command- This command will provide a hatch to some specific area of your drawing. While using
this command one has to take into mind that the area should be fully closed up otherwise this command
will not work.
24. G command- This command will group your objects together into one single object.
25. I command- This command will insert a block inside your drawing. After pressing this command user
has to browse the location of the block to be inserted inside the drawing.
26. LA command- This command will allow the user to open a dialogue box in which a user can manage the
layers inside the drawing.
27. PE command- This command will edit the polyline. After pressing the command software will ask to
select all the polylines to be close, join, adjust the width, edit vertex, fit lines, change it into spline, de
curve lines.
28. SP command- This command will check the spelling of all the words inside the drawing.
29. TB command- This command will allow inserting a table with the desired number of rows and columns
inside the drawing.
30. PO command- This command will allow the user to insert points inside the object as per user
requirements.
31. PU command- This command will open a dialogue box that will allow the user to remove unused/
unwanted elements inside the drawing.
32. RE command- This command will regenerate your drawing with the updates you had done in your
drawing.
33. REN command- This will allow the user to rename your layers, blocks inside the drawing in case you
want to change their names.

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34. T command- This will allow the user to insert multi-line text inside your drawing.
35. UN command- This command will allow selecting the measuring units of drawing. For example units in
inches, millimeters
36. U command- This command will allow the user to undo all previous commands.

WHAT IS A LAYER?
One drawing can have many layers. And depends on the complexity of the drawing, you may have a few to
dozens of layers.

You can use each layer to draw a specific object type. For example, you can use Wall layer to draw walls on
it. Furniture layer to draw furniture on it, and so on. AutoCAD supports tens of thousands layers in a single
drawing, which is virtually unlimited.

Changing active layer regularly to draw objects might seems tedious and takes longer to complete a drawing.
However, you will find it very useful during the design process and the drawing presentation.

WHEN ARE WE USING LAYERS?

The layering system is an essential drawing management in AutoCAD, and you should use layers in every
drawing. The common usage of layers is to draw objects on a layer based on their function. Create all
dimensions on a specific layer. Create walls, doors, windows on separate layers, and so on.

WHY ARE LAYERS USEFUL?

Layers can be useful in many ways.

First, because you draw objects on separate layers, it is easier for you to understand the drawing. You can
quickly know an object type by checking the layer. AutoCAD drawings are just lines and arcs. Using layers
can make the drawing easier to understand.

Second, you don’t have to set properties for each object. You only need to set the properties for the layers.
When you draw an object on a particular layer, it will have the same lineweight, color, linetype, and the other
properties. It gives you a better control to plot your drawing.

Third, you can hide/show or lock/unlock a layer. It means you can have greater control of your drawing. You
can lock several layers to prevent they are accidentally modified. You can hide objects when the drawing
becomes too complicated.

Fourth, using layers adds a better control to select and modify objects. Let’s say you want to select all
partition walls in your drawing and copy them to the next typical floor. AutoCAD doesn’t understand which
lines are partition walls. However, we can tell AutoCAD to select lines on the Partition Wall layer.

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Use the Layer Properties Manager to manage your layers.

 Create, rename, and remove layers

 Set the current layer on which new objects are automatically created
 Specify the default properties for objects on the layer
 Set whether the objects on a layer are displayed or turned off
 Control whether objects on a layer are plotted
 Set whether a layer is locked against editing
 Control the layer display properties for layout viewports
 Sort, filter, and group layer names

DIFFERENCES BETWEEN 2D & 3D DRAWING

Simply put, 2D drawing can be either an action or a product: You can draw in 2D and print or publish a 2D
drawing. In contrast, 3D drawing is only ever an action; it’s what you do when you’re setting up your design
for creating 3D models. You’re not going to create a 3D drawing, you’re going to create your shape using
3D drawing commands.

2D drawing is done in two dimensions with separate views, whereas 3D drawing adds a third dimension to
show depth all in one view.

With both types of drawing, we rely on elements such as points, lines, circles, and arcs, but 3D drawing
involves using them within three dimensions. 3D drawing also relies heavily on polylines instead of regular
lines. Unlike lines which have a single start and end point, a polyline is a series of connected lines or arcs
that are joined to create one object.

2D drawings can make it difficult for someone to visualize the finished product. But when you use 3D
drawing to create a 3D model, it’s much easier to show and explain what it is.

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 ABOUT MODELING 3D OBJECTS

Types of 3D Models
Several types of 3D modeling are available in AutoCAD. Each of these 3D modeling technologies offer a
different set of capabilities.

 Wireframe modeling is useful for initial design iterations and as reference geometry, serving as a 3D
framework for subsequent modeling or modification.
A wireframe model is a skeletal description of a 3D object. There are no surfaces in a wireframe model;
it consists only of points, lines, and curves that describe the edges of the object. With AutoCAD you can
create wireframe models by positioning 2D (planar) objects anywhere in 3D space.
 Solid modeling is efficient to use, easy to combine primitives and extruded profiles, and offers mass
properties and sectioning capabilities.
Solid Modeling is the computer modeling of 3D solid objects. The objective of Solid Modeling is to
ensure that every surface is geometrically correct. It is considered the most complex aspect to master in
computer-aided design (CAD) because it requires the CAD software to simulate the object from within
and outside
 Surface modeling offers fine control over curved surfaces for precise manipulation and analysis.
Surface modeling is a process that may require conversions between different 3D modeling types.
The typical surface modeling workflow is to: Create a model that combines 3D solids, surfaces, and
mesh objects. Convert the model to procedural surfaces to take advantage of associative modeling.
 Mesh modeling provides freeform sculpting, creasing, and smoothing capabilities.
A 3D model can include combinations of these technologies, and you can convert between them. For
example, you can convert a primitive 3D solid pyramid to a 3D mesh to perform mesh smoothing. You can
then convert the mesh to a 3D surface or back to a 3D solid to take advantage of their respective modeling
features.

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View 3D Models
The most useful command to view 3D models dynamically is 3DORBIT.

In addition to changing views, you can right-click to display a shortcut menu that provides many options.
The most popular options include the following:

 Change between different visual styles such as Conceptual, Realistic and X-Ray
 Switch between parallel and perspective projection
 Choose between standard preset views such as Top, Front,

Apply 2D and 3D AutoCAD Commands

Most AutoCAD commands that are used for 2D operations can be applied to 3D models. For example, with
the ROTATE command, you can revolve a 3D solid about an axis that's parallel with the Z axis of the UCS.
To rotate the model about a different axis direction would require you to change the direction of the UCS Z
axis.

There are also commands specialized for the 3D environment such as 3DROTATE, which displays a gizmo
to facilitate rotation about any major axis.

The easiest command to start with is ROTATE due to familiarity, however the choice of which command to
use depends on the circumstances and your preferences.

Related Concepts
 About Modifying the Properties of 3D Objects
 About Converting Surfaces and Meshes to 3D Solids
 Convert 2D Objects to 3D Objects (Video)
 Create and Modify Meshes (Video)
 Create and Modify Surfaces (Video)

WHAT ARE THE TYPES OF 3D MODELING?

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There are three major types of 3D models types: solid, wireframe, and surface. We base them on the
methods and techniques used to create different 3D objects. CAD (computer-aided design) offers many other
types, but most fall under those three

 WHAT IS SOLID MODELING?

Solid modeling is the most advanced method of geometric modeling in three dimensions. Solid modeling is
the representation of the solid parts of the object on your computer. The typical geometric model is made up
of wire frames that show the object in the form of wires. This wire frame structure can be two dimensional,
two and half dimensional or three dimensional. Providing surface representation to the wire three
dimensional views of geometric models makes the object appear solid on the computer screen and this is
what is called as solid modeling.

Advantages of Solid Modeling

Solid modeling is one of the most important applications of the CAD software and it has been becoming
increasingly popular of late. The solid modeling CAD software helps the designer to see the designed object
as if it were the real manufactured product. It can be seen from various directions and in various views. This
helps the designer to be sure that the object looks exactly as they wanted it to be. It also gives additional
vision to the designer as to what more changes can be done in the object.

Process of Making the Solid Models

To make the solid models you have to first make the wire frame model of the object and convert it into 3D
view. Thereafter the surfaces are added to the 3D wire model to convert it into 3D solid model. For creating
the solid models you need to have special CAD software that can create solid models. One of the most
popular CAD software for solid modeling is SolidWorks. Its latest version is SolidWorks 2009. A number of
other CAD software like AutoCAD and others also have features of creating the solid models.

Applications of Solid Modeling

Solid modeling is used not only for creating solid models of machine parts, but also the buildings, electric
circuits and even of the human beings. The solid modeling software are being used for a large variety of
applications, here are some of them:

1) Engineering: The engineering design professionals use solid modeling to see how the designed product
will actually look like. The architects and civil engineers use it to use the layout of the designed building.

2) Entertainment industry: The animation industry has been using solid modeling to create various
characters and the movies out of them.

3) Medical industry: Modern imaging scanners are being used to create the solid models of the internal parts
of the body. This helps the doctors to visualize specific tissues of the body, designing various medical
devices etc.

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  WHAT IS WIRE FRAME MODELING?
Wire frame modelling is one of the methods used in geometric modelling systems. A wireframe model
represents the shape of a solid object with its characteristic lines and points. The word “wireframe” is related
to the fact that one may imagine a wire that is bent to follow the object edges to generate a model.
In other words, a wire frame model is an edge or skeletal representation of a real-world 3D object using lines
and curves.
Model consists entirely of points, lines, arcs and circles, conics, and curves. In 3D wireframe model, an
object is not recorded as a solid. Instead the vertices that define the boundary of the object or the
intersections of the edges of the object boundary are recorded as a collection of points and their connectivity.

One can use a wire frame model to

1. View the model from any vantage point

2. Generate standard orthographic and auxiliary views automatically
3. Generate exploded and perspective views easily
4. Analyse spatial relationships, including the shortest distance between corners and edges, and
checking for interferences
5. Reduce the number of prototypes required

Advantages of Wireframe model:

1. Simple to construct
2. Designer needs little training
3. System needs little memory
4. Take less manipulation time
5. Retrieving and editing can be done easy
6. Consumes less time
7. Best suitable for manipulations as orthographic isometric and perspective views.

Disadvantages of Wireframe model:

1. Image causes confusion

2. Cannot get required information from this model
3. Hidden line removal features not available
4. Not possible for volume and mass calculation, NC programming cross sectioning etc
5. Not suitable to represent complex solids

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  WHAT IS SURFACE MODELLING TECHNIQUE?
When we talk about surface modelling, it is basically used to create complex shape of a feature on the
external facets of an object. Technically the CAD software, it develops an object by extending a surface over
it and with the help of 3D curves that are produced by the designer. In other words, you are depicting the
boundaries of the surface of an object.

In this type of modelling, the user can actually see the entire surface points beneath which the solid interiors
are present. Surface models actually define the surface features, including the edges of an object. This is
another example where surface modelling techniques can help. While solid modelling tools helps you build
several sides of a shape at once, while surface modelling tools let you build one face at a time so you can
control the exact contour and direction of that face.

Surface freestyle tool

Freestyle tool works based on sub-divisional modelling technique. With this, you start to model a primitive
shape, for example a sphere or cube. This shape is surrounded by a control mesh. The mesh can be used to
manipulate the primitive geometry. If you pick any of the elements of the control mesh such as a vertices, an
edge or a plane, you will get a 3D dragger. One can manipulate the geometry directly with the use of the
dragging tool. As you move the control mesh, the surface will be automatically built with high quality
curvature.

Pros of Surface modelling

 Surface modelling allows to create more free-form shapes.
 It is more definitive in nature. There is no unnecessary ambiguity in this modelling technique.
 Creation of complex surfaces is easier in comparison with other modelling techniques.
 More realistic approach for creating free form objects
Cons of Surface modelling
 The steps in Surface modeling are not parametric and hence it can be hard to make design changes.
 It is rather difficult to construct.
 This methodology is more time-consuming in comparison to others.
 Surface modeling also requires a large amount of storage space.

THE BIM CONCEPT

Definition:BIM=Building Information Modeling

Also known as “Virtual Building” or “Building Simulation”

The basic concept of BIM modeling is that architects are able to use the 3D building
model to extract all the required project drawings and building views–including

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sections and elevations, presentation drawings, renderings and detailed construction
drawings, as well as quantity calculations and price estimations. Consequently,
changes to the model are instantly updated on all drawings. The image below is an
illustration of this concept.
Working with a 3-Dimensionalbuildingmodelgives the architect’s flexibility and
benefits that are not available in a traditional 2Dbuildingproject.Thecommonly used
phrases ‘Virtual Building’, ‘Building Simulation’and‘Building Information Modeling ‘are
largely interchangeable.
WORKING CONCEPT OF BIM

The most significant high lights of the BIM method are:

• Single file concept :The complete building model and all of its representations are
included in the virtual building file
• Real architectural elements used for modeling
• Changes to the model affect all related drawings (and vice versa)
• Automatic generation and updating of documentation
• Architectural content(libraries)
• Building information data attached to the elements
• Additional materials (rendering, animation ,quantity take-offs ,schedules)
• We must emphasize that unlike in 3DCAD, the BIM model consists of real architectural
elements (walls, slabs, roofs,etc.)And the documentation work flow is automatic.

EVALUATION OF THE BIM CONCEPT

Since the BIM concept was initially developed to serve the AEC market, it offers many
particular advantages for architects and designers compared to traditional CAD
methods. The only possible drawback of BIM is his relatively higher training
requirements of novice users and cross graders from 2D applications.
Benefits

Compared to 2D and 3D CAD

• Elements have architectural meaning
• Changes on one drawing have influence on all others
• Rich visualization content (animation, sun studies, renderings etc.)
• Automatic quantity take-offs, schedules
• Connectiontostructural,energycalculation,collisiondetectionetc.software

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Drawbacks
• Higher training requirements
• Might be difficult to learn the BIM approach for people who were previously 2D users
• Might be more difficult to handle complex geometry(e.g. free forms structures)then in
3D and 2D CAD

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 EVOLUTION OF AEC CAD
CAD (Computer Aided Design) applications have gone through major changes over the
course of time. The evolution of CAD software was particularly significant in the AEC
(Architecture, Engineering and Construction) industry, in which simple two
dimensional drafting programs have evolved into integrated building information
modeling (BIM) applications during the past 30years.The most important mile stones of
AECCAD are the following:
• 2D solutions

Electronic drafting board

• 3D solutions

Modeling for purely visualization purposes

• BIM solutions

Models with integrated architectural information

• Construction Coordination (5D)

Timing/scheduling and Cost estimation

Early commercial CAD applications were no more than electronic drafting boards
capable of creating 2D drawings only.

A major millstone of AEC software history was there lease of 3DCAD applications
capable of handling three-dimensional models in addition to the 2D documentation.
Some of these programs also had basic visualization functions, such as photo
rendering engines and simple movie tools.
Contemporary BIM applications provide integrated solutions for architects and
designers. Developed specifically for the AEC industry, the BIM programs feature real
building elements, automatically attached building information data and rich
visualization capabilities.
The latest AEC applications focus on the construction industry. Adding time and cost
information to the 3D BIM model (making it in to a so-called “5D” model) allows
construction companies to optimize their processes and minimize the risk of building
errors.

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AECCADTIMELINE

The history of CAD goes back to the early sixties .In this pioneering era of computer
science, researchers and programmers laid the foundations of the CAD industry.
Computer input devices (such as the mouse) and basic computer interface techniques
were also invented that time.
The first commercial CAD applications were released in the seventies for main frame
computers and workstations. Since these machines were very expensive, computer-
aided drafting remained the privilege of state institutions and large design firms
(mainly in the engineering industry).

The breakthrough in CAD usage came in the early eighties, with the appearance of
personal computers on the market. The drop in computer prices opened the way for smaller
architectural firms to start experimenting with CAD drafting.

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Thanks to the rapid development of computer hardware and computer programming,
within a few years 3D CAD solutions followed the 2D CAD applications.
By the end of the eighties, CAD developers realized that different industry segments
required different solutions.The1990 were characterized, then, by specialization of CAD
software. The Building Information Modeling concept was also developed during these
years, although some revolutionary CAD companies released similar products in the
early eighties.
The latest trend in the industry is the integrated solution offered for construction
companies. This approach is also known as 5D CAD (3D+time+cost).

The adoption of new CAD concepts by institutions and businesses usually followed the
industry innovations with a few years delay. The accompanying chart shows the
tendencies in CAD usage during the past 30 years.
As you can see, from the mid-80s onwards, more and more of the industry has adopted
some form of CAD, and we are now going to discuss the 3 most common CAD methods
• 2DCAD
• 3DCAD
• BIM

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 PLANAR PROJECTIONS

Planar projections, also called azimuthal projections, project map data onto a flat surface. The simplest planar
projection is tangent to the globe at one point. Although the point of contact may be any point on the earth's
surface, the north and south poles are the most common contact points for most GIS databases. Other
locations are used primarily for specific applications, such a navigation or locational inset maps.
When the plane touches the earth at either the north or south poles, longitude lines converge at the point of
contact and radiate outward from the pole at their true angle like the spokes on a wheel, the distance between
them increasing as the distance from the contact point increases. Latitude lines appear as a series of
concentric circles.

This particular map projection's light source originates at the center of the earth,
but this is not true for all planar map projections.

Because area and shape distortion are circular around the point of contact, planar projections accommodate
circular regions better than rectangular regions. For this reason, they are used most often to map Polar
Regions.
In the polar form, longitude lines passing through the point of contact are represented by straight lines and
directions from the point of contact are accurate.
Some planar map projections, such as the example above, represent all great circles as straight lines. Because
the shortest distance between two points on the globe is a great circle, or a portion of a great circle, the
shortest distance between two points on this type of projection is also a straight line. This makes planar map
projections that maintain this trait extremely useful for plotting navigational routes for airplanes.

Projection is the process of reproducing a spatial object on a plane, curved surface, or line by projecting its
points. Common examples of projection include photography, where a 3D scene is projected onto a 2D
medium, and map projection, where the earth is projected onto a cylinder, a cone, or a plane in order to create
a map. Planar projection figures prominently in both engineering and computer graphics. For our purposes,
a projection is a mapping of a three-dimensional (3D) space onto a two-dimensional subspace (i.e., a plane).
The word projection also refers to the two-dimensional (2D) image resulting from such a mapping.

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Every planar projection includes the following elements:

 The 3D object (or scene) to be projected

 Sight lines (called projectors) passing through each point on the object
 A 2D projection plane1
 The projected 2D image that is formed on the projection plane

The projection is formed by plotting piercing points created by the intersection of the projectors with the
projection plane. By mapping these points onto the projection plane, the 2D image is formed. In effect, three-
dimensional information is collapsed onto a plane.

DIFFERENCE BETWEEN THE TRADITIONAL/DIRECT GEOMETRIC

METHOD AND USE OF PARAMETRIC DRAWING TOOLS-

Design and revision procedures; and this is done through the use of parametric features. Parametric
features control the model geometry by the use of design variables.

What Is Parametric Modeling?

Parametric modeling is an approach to 3D CAD in which you capture design intent using features and
constraints, and this allows users to automate repetitive changes, such as those found in families of product
parts.

What Is Traditional/Direct Modeling?

Direct modeling empowers you to define and capture geometry quickly, without spending time worrying
about features, constraints, and original design intent. It is often compared to working with modeling clay.
Simply push and pull the geometry until you arrive at the shape you want.

Pros and Cons of Direct vs. Parametric Modeling

So which is better, direct or parametric modeling? The answer is “all of the above.” While each has its
benefits, the best CAD software uses both approaches to modeling. Manufacturers that integrate direct
modeling into their parametric environment report greater speed, quality, and focus on innovation that helps
them stay ahead of the competition.

But before we talk about that, let’s weigh some of the pros and cons of direct vs. parametric modeling.

WHAT IS THE DIFFERENCE BETWEEN ANSI AND ISO STANDARDS.

What are ANSI and ISO standards? ANSI stands for American National Standards Institute which writes
standards intended for use in the US. ISO is the International Standards Organization, which writes standards
for all its member states.

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ANSI dimensions are read horizontally. ISO dimensions are parallel to the dimension line.
ANSI dimensions are centered on the dimension line. ISO dimension are placed above the dimension line.
ANSI tends to use abbreviations. ISO uses symbols. (Example: RAD, DIAM, 3 PLACES versus R, Ø, 3X)

Dimensions have a different syntax.

ANSI: 1.000 DIAM 3 PLACES
ISO: 3X Ø 1.000
The American National Standards Institute (ANSI, /ˈænsi/ an-see) is a private non-profit organization that
oversees the development of voluntary consensus standards for products, services, processes, systems, and
personnel in the United States.

The organization also coordinates U.S. standards with international standards so that American products can
be used worldwide.

ANSI accredits standards that are developed by representatives of other standards organizations, government
agencies, consumer groups, companies, and others. These standards ensure that the characteristics and
performance of products are consistent, that people use the same definitions and terms, and that products are
tested the same way. ANSI also accredits organizations that carry out product or personnel certification in
accordance with requirements defined in international standards.

The organization's headquarters are in Washington, DC. ANSI's operations office is located in New York
City. The ANSI annual operating budget is funded by the sale of publications, membership dues and fees,
accreditation services, fee-based programs, and international standards programs…

he Institute administers nine standards panels:

•ANSI Homeland Defense and Security Standardization Collaborative (HDSSC)
•ANSI Nanotechnology Standards Panel (ANSI-NSP)
•ID Theft Prevention and ID Management Standards Panel (IDSP)
•ANSI Energy Efficiency Standardization Coordination Collaborative (EESCC)
•Nuclear Energy Standards Coordination Collaborative (NESCC)
•Electric Vehicles Standards Panel (EVSP)
•ANSI-NAM Network on Chemical Regulation
•ANSI Biofuels Standards Coordination Panel
•Healthcare Information Technology Standards Panel (HITSP)

whereas ISO!!

The International Organization for Standardization (ISO) is an international standard-setting body composed
of representatives from various national standards organizations.

Founded on 23 February 1947, the organization promotes worldwide proprietary, industrial and commercial
standards. It is headquartered in Geneva, Switzerland, and as of 2015 works in 163 countries.

It was one of the first organizations granted general consultative status with the United Nations Economic
and Social Council.

ISO, the International Organization for Standardization, is an independent, non-governmental organization,

the members of which are the standards organizations of the 163

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Member countries. It is the world's largest developer of voluntary international standards and facilitates
world trade by providing common standards between nations. Nearly twenty thousand standards have been
set covering everything from manufactured products and technology to food safety, agriculture and
healthcare.

Use of the standards aids in the creation of products and services that are safe, reliable and of good quality.
The standards help businesses increase productivity while minimizing errors and waste. By enabling
products from different markets to be directly compared, they facilitate companies in entering new markets
and assist in the development of global trade on a fair basis. The standards also serve to safeguard consumers
and the end-users of products and services, ensuring that certified products conform to the minimum
standards set internationally.

IT depends upon where you are working and whom you are working!!

If you are working for American based product then ANSI will come first and rest ISO will come

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