Computer Graphics Final Exam Flash Cards

implicit vector equation of sphere formula

(p-c) * (p-c) - R^2

normal vector at a point on a sphere formula

(p-c)/R

Reasonable values for phong exponent in Blinn-Phong reflection formula: -matte/eggshell -somewhat shiny -glossy

-15 -180 -2000

Control points

-interploting -approximation

What scenarios do surface materials permit an object to have its own highlisht/specular color as distinct from the color of the lights

-some metals the diffuse reflectance contributes to the highlight color -dimming the highlight can prevent washout when the value exceeds 1

briefly explain the concept of separable filter and how it relates to convolutions in 2D

A seperable filter is one that can be represented as the simple product of two other filters. For 2D convulution, this means that we can construct two-dimensional filters by defining two seperate one-dimensioonal filters and simply multiply them together

Graphics Pipeline

Application --> Vector Processing --> Rasterizer --> Fragment Processing --> Frame Buffer Vextex Data --> Assembled Primitives --> Fragments --> Shaded fragments --> final Pixels

DDA vs. Bresenham

DDA- each time through the loop it updates the previous y-coordinate by asome fixed amount instead of recalculating it x from each time (incremental) Brensham -removes any fractional division (integer)

In gourad shading and phong shading what quantities are varied across the fragment

Gouraud - color Phong - normal vector

What is a scenario where a texture coordinate function would be bijective or one-to-one

a human face with many unique bumps and wrinkles

spline

a representationm of a curve defined by a piecewise parametric function

scene graph

a scene that can be managed by hierarchal organization (Car example)

aliasing

a set if samples can match multiple continuous signals

The phenomenon examined in the previous question, is when more than one signal is consistent with the same discrete set of samples is called

alias

If we define texture coordinates at each vertex, we can varythem across the face of a triangle using ______

barycentric interpolation

What method does the hardware rasterizer use to compute varying quantities across fragments in screen space

barycentric interpolation

given two non-parallel vectors a and b, how do we obtain a third vector that is perpendicular to both a and b

c can be found by cross computing the product a*b

piecewise

collection of curves that appropriate asmooth curve

gamma correction

controls the overall brightness of an image

samples

discrete measurements a continuous signal

convolution operation has what properties

distributive, associative, commutative, identity

reducing the number of samples by keeping only every Nth sample by keeping only every Nth sample, this is known as

down

to verify that a triangle mesh is a manifold, it suffices to check what two conditions

every edge is shared by exactly two triangles, every vertex is surrounded by exactly one complete loop of triangles

the gaze vector can be derived from

eye position and view reference point

Psuedocode for Ray Tracing

for each pixel do compute viewing ray if(ray hits an object with t ∈ [0, ∞)) then compute n Evaluate shading model and set pixel to that color else set pixel to background color

Depth Buffer

for(each object, object in scene) rasterize, obj initialize z-buffer to ∞ for each frag(i,j) < depth Buffer (i,j) colorBuffer(i,j)

Per-fragment shading vs. per-primitive shading vs. per-vertex shading

fragment - shades fragment vertex - shades each triangle specifically primitive - shades specifc shapes

halfway vector formula

h = (v+l)/ ||(v+l)||

Lambertian diffuse illumination formula

kdI max(0, n*l)

Phong specular illumination formula

ksI max(0, v*r)^p

Many pixels to one texel

mag

many texels to one pixel

min

pre-computing lower resolution versions of a texture image to allow more efficient access to downsamples texture values for higher quality antialiasing, these smaller downsamples images are called _________

mip

Name two different application areas where comp graphics can be used

movies, games, medical images, etx

ray equation

p(t) = e + td

spline curves

piecewise lineup curve, polygonal "spline"

reflection vector formula

r = d -2(d*n)n

basic ray tracing algorithm

ray generation --> ray- object intersection --> shading

Cohen-Sutherland line-clipping algorithm

reliable, and easy to understand. It uses what is termed 'inside-outside window codes' (It is the the grid of bytes)

Three core areas of computer graphics

rendering, animation, modeling

approximation

spline curve doesn;t pass through but affected by them

How does the phong reflection model change when there are multiple lights

sums up the combination of multiple lights

why do we include ambient constant in the reflection modelsums up the combination of multiple lights

sums up the combination of multiple lights

what simple change can we make to the standard shading computation to simulate two-sided lighting

take the absolut value of dot-product n*l instead of clamping negative values 0

if a ray surface intersection equation has several distinct real solutions, then what is the correct geometric interpretation of this algebraic result

the ray intersects at more than one point

what does it mean to say that ray-tracing is an image order approach to rendering

the rendering loop iterates for each pixel

We can achieve a more compact representation by representing the top and bottom of this octahedron with which of the following compression strategies

triangle fans

if we increase the number of samples by inserting interloped values , we call this`

up

a texture coordinate function φ maps ____ to points in ____

world space, texture space