Lecture 5: Basic Graphics Primitives Rendering Flashcards
The basic geometric objects in CG(Computer Graphics) are usually called ? or ?
(fill in the blanks)
(not same answer)
primitives. graphic output primitives
is a graphics object that is essential for the creation or
construction of complex images.
(identify)
primitive
Fortunately, ? is constructed from a few basic elements, as
opposed to the great variety of graphics applications.
(identify)
graphics
Graphics Primitives Include:
(enumerate)
- Lines
- Areas
- Circle
- Rectangle primitive
- Arc
Graphics Primitives Include:
?, especially straight ?, constitute an important building block of computer images.
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(same answer)
Line/s
Graphics Primitives Include:
Lines/Straight lines
A straight line can be developed in two different ways:
(enumerate)
- Structural method
- Conditional method
Graphics Primitives Include:
Lines/Straight lines: Structural Method
(describe)
determines which pixels should be set before drawing the line
Graphics Primitives Include:
Lines/Straight lines: Conditional Method
(describe)
tests certain conditions to find which pixel should be set next
Graphics Primitives Include:
Lines/Straight lines
need two points and additional control points.
(identify)
Curves
Graphics Primitives Include:
Lines/Straight lines
are connected sequences of lines.
(identify)
Polylines
Graphics Primitives Include:
are bounded by closed polylines or polygons.
(identify)
Areas
Graphics Primitives Include:
can be filled with colour or a texture.
(identify)
Areas
Graphics Primitives Include:
Areas
even though generally constructed from straight lines, is an important graphics primitive.
(identify)
Polygon
Graphics Primitives Include:
Areas
is a closed area of image bounded by straight or curved lines and filled with one solid colour.
(identify)
Polygon
Graphics Primitives Include:
is an eight-way symmetric figure.
(identify)
Circle
Graphics Primitives Include:
Circle
The ? is the same in all quadrants.
(fill in the blanks)
shape of circle
Graphics Primitives Include:
draws a rectangle with a given starting top left point(x and y coordinates) and a delta x and delta y, plus a line weight and line pattern.
(identify)
rectangle primitive
Graphics Primitives Include:
is drawn as a portion of an oval.
(identify)
Arc
Graphics Primitives Include:
Arc
are measured in degrees.
(identify)
Arc angles
Graphics Primitives Include:
Arc
? from a starting angle by the number of degrees specified by their arc angle.
(identify)
Arcs sweep (i.e., move along a curve)
Graphics Pipeline
(enumerate)
- Application program
- Application data structure
- Graphics system
Graphics Pipeline
This is a collection of output plotting subroutines based on 2D or 3D geometry of the object to be displayed
(identify)
Application program
Graphics Pipeline
Application Program
performs the following:
(enumerate)
- View transforms
- Converts from viewport to normalized device coordinates (NDC)
- Clips
- Maps data to device coordinates
Graphics Pipeline
Application Program
specifies what part of the world scene is to be displayed and converts those points into view coordinate points.
(identify)
View transforms
Graphics Pipeline
Application Program
specifies where in the view surface should the object be displayed.
(identify)
Converts from viewport to normalized device coordinates (NDC)
Graphics Pipeline
Application Program
Determine visible surfaces and shading. Then, the object outside the NDC is clipped.
(identify)
Clips
Graphics Pipeline
Application Program
All the geometric and non-geometric details in the data structure are converted to one of the graphics output primitives and passed to the graphics system i.e. the objects are scan converted into pixels and the framebuffer displayed.
(identify)
Maps data to device coordinates
Graphics Pipeline
This is a database of descriptions and properties, like geometric coordinates, colour, surface texture and connectivity relationships of objects to be displayed on the display unit of the graphics system.
(identify)
Application data structure
Graphics Pipeline
This handles the low-level architecture of the display processor and xy co-ordinate system of the physical screen, hiding these details from the user.
(identify)
Graphics system
Line Drawing
(enumerate)
- Straight line
- Line
- Line drawing
- (DDA Algorithm) The Digital differential analyzer algorithm
Line Drawing
Given the specification for a ?, find the collection of addressable pixels which most closely approximates this line.
(fill in the blanks)
straight line
Line Drawing
in Computer graphics is a portion of straight line that extends indefinitely in opposite direction 2.
(identify)
line
Line Drawing
It is defined by its two end points.
(identify)
line
Line Drawing
is accomplished by calculating intermediate positions along the line path between two specified end points positions.
(identify)
Line drawing
Line Drawing
is an incremental scan-conversion method. Such an approach is characterized by performing calculations at each step using results from the preceding step.
(identify)
(DDA Algorithm) The Digital differential analyzer algorithm
Line Drawing
is a scan-conversion line algorithm based on calculation either ∆y or ∆x
(identify)
(DDA Algorithm) The Digital differential analyzer algorithm
Line Drawing
Limitations of DDA
The ? & ? are time consuming procedures.
(enumerate)
- rounding operation
- floating point arithmetic
Line Drawing
Limitations of DDA
? can cause the calculated pixel position to drift away from the true line path for long line segment.
(identify)
Round-off error
Line Drawing
Limitations of DDA
? can cause the calculated pixel position to drift away from the true line path for long line segment. The big advantage of this algorithm is that it uses only integer calculations.
(identify)
Bresenham algorithm
Line Drawing
Limitations of DDA
? An accurate and efficient raster line generating algorithm developed by Bresenham that uses only incremental integer calculations
(identify)
Bresenham’s Line Algorithm
It is a process of representing graphics objects a collection of pixels.
2D Scan Conversion
2D Scan Conversion
The graphics objects are ?.
(fill in the blanks)
continuous
2D Scan Conversion
The pixels used are ?. Each pixel can have either on or off state.
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discrete
2D Scan Conversion
Any model of graphics can be reproduced with a dense matrix of ?.
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dots or points
2D Scan Conversion
Most human beings think ? as points, lines, circles, ellipses.
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graphics objects
2D Scan Conversion
For generating graphical object, not many algorithms have been developed.
(true or false)
false: For generating graphical object, not many algorithms have been developed.
true: For generating graphical object, many
algorithms have been developed.
2D Scan Conversion
The process of converting is also called as ?. The algorithms implementation varies from one computer system to another computer system.
(fill in the blanks)
rasterization
2D Scan Conversion
Some algorithms are implemented using ?
(identify)
Software
2D Scan Conversion
Some are performed using:
(enumerate)
- Hardware or Firmware
- Various combinations of hardware, firmware, and software
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
(enumerate)
- Scan-Converting
- Scan Converting a Straight Line
- Circle-Generating Algorithms
- Ellipse-Generating Algorithms
- Line Attributes
- Mid-point circle drawing algorithm
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
a point involves illuminating the pixel that contains the point.
(identify)
Scan-Converting
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
A straight line may be defined by two endpoints & an equation.
(identify)
Scan Converting a Straight Line
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
General function is available in a graphics library for displaying various kinds of curves, including circles and ellipses.
(identify)
Circle-Generating Algorithms
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
An ellipse is an elongated circle. Therefore, elliptical curves can be generated by modifying circle-drawing procedures to take into account the different dimensions of an ellipse along the major and minor axes.
(identify)
Ellipse-Generating Algorithms
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
Basic attributes of a straight line segment are its type, its width, and its color. In some graphics packages, lines can also be displayed using selected pen or brush options
(identify)
Line Attributes
Algorithm for drawing Line, Circle, Ellipse, Arcs, & Sectors
is an algorithm used to determine the points needed for rasterizing a circle.
(identify)
mid-point circle drawing algorithm
