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Questions tagged [graphics]

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3 votes
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What is the most efficient algorithm for finding the bounding inequalities of a cone given the extremal rays?

Say that I am given a cone, as specified by the extremal rays whose facets form its convex hull, what is the most efficient algorithm that finds the linear-rank inequalities whose intersection defines ...
Ning Bao's user avatar
4 votes
1 answer
383 views

Why there is light source?

In ray tracing if we are tracing a ray from camera to the object, then why there is need for light source as in this image and also rays are going towards the light source instead of outgoing from the ...
Mr.Grey's user avatar
  • 171
0 votes
0 answers
299 views

Formula for rays in ray tracing

Each time the camera generates a ray, the first task of the renderer is to determine which object, if any, that ray intersects first and where the intersection occurs. This intersection point is the ...
Inder Gill's user avatar
3 votes
0 answers
558 views

Algorithm to outline a group of points

I have a set of coordinates, in practice gps coordinates. Some of them are in clusters and some of them are scattered. Which are which is allready determined. Thus I know which ones are in a ...
Einar Sundgren's user avatar
1 vote
0 answers
50 views

Draping data onto an elevation map

I'm looking for a computational method for projecting data from one grid onto another dissimilar grid while preserving the area of the original grid. I'm not quite sure what these methods would be ...
vincentjs's user avatar
-1 votes
3 answers
246 views

Why do I need high fps values in simulations? [closed]

Sometimes I see NVIDIA simulations with an additional information abbreviated "fps". I've figured out that fps stands for frames per second, but isn't it enough to support 25 fps? Why do I need 60fps ?...
Jorgos's user avatar
  • 111
4 votes
0 answers
108 views

Computing average tile size (grid)

I am trying to compute the average cell size on the following set of points, as seen on the picture: . The picture was generated using gnuplot: ...
malat's user avatar
  • 141
0 votes
1 answer
477 views

Blob detection as Constraint satisfaction problem?

In image processing I have a black and white image which is represented by matrix {0,1}, I have to find blob (a region of connected pixels) in it. I'm confused, can this problem be reduced to ...
Thanos's user avatar
  • 113
0 votes
0 answers
527 views

Camera Matching Algorithm

I am trying to understand how camera matching (or match moving) works. I need to build a program that can move the camera in a way to match a 3D object to its projection on an image. For eg. if I had ...
shish023's user avatar
  • 101
1 vote
1 answer
116 views

Is there a way to predict rendering times? [closed]

In purpose of load balancing I need to approximatively predict rendering time my graphics software (in the specific case it's Autodesk Maya) needs to render a task given an input file (.ma/.mb) and ...
SemmZemm's user avatar
-1 votes
1 answer
66 views

Why do 3D engines use rectangular projections for the camera perspective?

In most 3d applications, the scene is projected onto a rectangular area. As the field of view increases, you see terrible distortions near the edges of the screen. Why do modeling engines limit ...
Matt's user avatar
  • 7
3 votes
0 answers
217 views

Simplify closed-path points without intruding into the inside of the path

I want to: Simplify a set of points that outlines a closed opaque image on a transparent background. The simplified set of points should not intrude into the closed opaque image. I use a Marching ...
markE's user avatar
  • 131
7 votes
2 answers
1k views

What are all the differences between the Gibbs phenomenon artefects and JPEG artefacts?

I thought the Gibbs phenomenom is the result of Fourier analysis estimation (but was it Fourier Series estimation or can it also be Fourier Transform estimation?) JPEG uses the Discrete cosines ...
Higgins's user avatar
  • 91
2 votes
1 answer
258 views

Resizing and aliasing in computer science [closed]

If you resize an 1000x1000 raster image to 10x10 and resize it back to 1000x1000 is this considered to be an example of aliasing?
Higgins's user avatar
  • 91
1 vote
1 answer
6k views

How does the midpoint line drawing algorithm work?

I'm having trouble understanding the mechanics of the midpoint algorithm. I understand the gist of what it does; it keeps us within a half a pixel of where the actual line should be printed. It does ...
CodyBugstein's user avatar
  • 2,967
2 votes
0 answers
63 views

Stream processor definition

I'm looking for an actual definition of a stream processing unit (SPU), preferably sourced. The context is not specifically graphics cards. I can find many, many articles explaining what they contain,...
user234461's user avatar
1 vote
1 answer
635 views

Sphere, triangle, and other primitive shape intersection

In a three dimensional Cartesian space, given a ray in its parametric form: $r(t) = [1, 1, 1] + t[-1, -1, -1]$ find the intersection points between the ray and the following primitives. a) A sphere ...
LulzCow's user avatar
  • 111
3 votes
2 answers
340 views

Closing shapes at non-endpoints

Consider how one would represent the following image in vector graphics: Pretty simple, right? The entire shape can be represented by a single path element. But suppose additionally that you want ...
Guest's user avatar
  • 53
2 votes
1 answer
1k views

How to do pixel array rotation whose angle not a multiple of 90 degree?

It is easy to rotate pixel array if the angle is a multiple of 90 degree. For example, (quote from Computer Graphics with OpenGL) We can rotate a two-dimensional object or pattern 90' counterwise ...
Jichao's user avatar
  • 121
3 votes
1 answer
3k views

What the difference between the Fourier Transform of an image and an image histogram?

Consider this small picture of a sunflower, and its histogram: What would the Fourier transform of the first picture look like? Is there any relationship between the histogram and the Fourier ...
user8005's user avatar
2 votes
1 answer
14k views

How do I compute the luminance of a pixel?

I have a color (say $R=100, G=150, B=130$). How do I compute its intensity? Do I just sum up all three components? Or are the colors not evenly weighted?
David Faux's user avatar
  • 1,607
1 vote
2 answers
3k views

Computer graphics: Linear Interpolation

I have two vector points $p_1$ and $p_2$. Each point has a color value $c_1$ and $c_2$. Now using linear interpolation, I would like to get the color value at point $p_3$. Concrete example: $\qquad \...
Clueless's user avatar
7 votes
1 answer
2k views

Line smoothing algorithm that perserve data uniformity

Intro: I'm working with huge data set that i need to plot in browser, and since there may be up to 1M points my idea was to create different representations for different zoom levels lets say i have ...
Dragan B.'s user avatar
  • 171
1 vote
1 answer
196 views

Extreme instancing for computer graphics

Instancing in GPU's, from my little knowledge, simply draw the same object at multiple locations. Each "instance" is just a copy of the same model at a different location. Any local effects, such as ...
Archival's user avatar
  • 171
6 votes
1 answer
349 views

Radon transform for advanced 3d graphics and games?

The Radon transform is used to take 2d projections of an object and create a 3d representation. It seems like it would be possible to apply such a transform in 3d graphics in games (although possibly ...
Archival's user avatar
  • 171
1 vote
0 answers
55 views

A text for virtual environments seminar

What is a good textbook for a seminar about virtual environments, virtual worlds, augmented reality and similar topics? The seminar is at the graduate studies level and is supposed to give ...
elomage's user avatar
  • 131
10 votes
3 answers
2k views

Intuition for convolution in image processing

I have read many documents about convolution in image processing, and most of them say about its formula, some additional parameters. No one explains the intuition and real meaning behind doing ...
hqt's user avatar
  • 223
10 votes
1 answer
2k views

How to find contour lines for Appel's Hidden Line Removal Algorithm

For fun I am trying to make a wire-frame viewer for the DCPU-16. I understand how do do everything except how to hide the lines that are hidden in the wire frame. All of the questions here on SO all ...
Scott Chamberlain's user avatar
10 votes
1 answer
1k views

Is the shadow ray in a Whitted ray tracer occluded by transparent objects?

In a Whitted ray tracer, each ray-object intersection spawns a transmitted ray (if the object was translucent), a reflected ray and a shadow ray. The shadow ray contributes the direct lighting ...
user11171's user avatar
  • 203
19 votes
3 answers
2k views

Ray Tracing versus object-based rendering?

Intro graphics courses usually have a project that asks you to build a ray tracer to render a scene. Many graphics students entering grad school say that they want to work on ray tracing. And yet it ...
Suresh's user avatar
  • 5,387
15 votes
2 answers
403 views

Which method is preferred for storing large geometric objects in a quadtree?

When placing geometric objects in a quadtree (or octree), you can place objects that are larger than a single node in a few ways: Placing the object's reference in every leaf for which it is ...
nsantorello's user avatar

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