# Tagged Questions

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32 views

### How can I find the “thinner” path from a cloud of coordinates? [migrated]

Following up with this, I have a bunch of coordinates and I draw them on a bitmap image as a coordinate system. Now, I would like to get rid of all the noise, and filter coordinates to give a "clearer"...
19 views

### transformation between two coodinate system [closed]

I have two coordinate system; camera coordinate system and monitor coordinate system. I want to obtain the translation and rotation between these two coordinate system. the camera is placed under the ...
14 views

### What's the relationship of max-flow-min-cut and Markov Random Fields?

I am trying to follow this paper [1]. There is a relationship between Markov Random Fields (MRF) to max-flow-min-cut. An MRF can be represented as an undirected graph, and you can find flow through it,...
30 views

### Hyperplane through origin which goes through most number of points

Given $M$ points in $\mathbb{R}^{N}$ (where $M$ is larger than $N$), I was wondering if there is an algorithm to find a $N-1$-dimensional hyperplane which goes through the origin and also intersects ...
25 views

### Amount of information in scaled-down images

Does an image that is scaled down lose more Information when calculating averages of pixels rather than selecting single pixels? One way to scale down an image is to replace 2x2 pixel blocks with ...
64 views

### Algorithm for antialiasing thin lines

A very tricky problem in graphics rendering is drawing thin lines ($1px$ width) that do not look jaggy. The only implementation I have seen that is very good is that in Mathematica, but their ...
2k views

### How to generate stereo image pair from a stationary mono camera?

I have a stationary mono camera which captures a single image frame at some fps. Assume the camera is not allowed to move,how do i generate a stereo image pair of the acquired frame? Is there any ...
23 views

### Dither pattern to detect a copy?

I am printing a document and I want to print an emblem on it that will be copy resistant. For example, let's say I print the document using a 600 dpi printer. Someone copies the document on a ...
296 views

### How Is a Computer Able to Store and Quickly Manipulate All the Data Required For A Computer Display?

I did some quick math on how much data is contained on a screen at any given instant and I ended up with a number well beyond what I thought was possible. 256 colors for Red, Green, and Blue each ...
69 views

### What's the point of 48 bit colour?

I've read that the human eye can only really decipher around 10 million different colours, so what's the point in technology that uses 48-bit colour, which allows for $2.81\times 10^{14}$ colours....
37 views

### Rotating a set of points around two fixed points

I have a set of points that are used to draw a shape. I want to rotate this shape without moving its start and end points. I tried to illustrate what I want in the image below (original shape on left, ...
245 views

### What is the difference between a R-tree and a BVH?

I've just read about R-Trees: The key idea of the data structure is to group nearby objects and represent them with their minimum bounding rectangle in the next higher level of the tree; the "R" ...
46 views

### Point in Polygon Problem: Has anybody invoked the line integral?

Some twenty years prior I was given the task to solve the Point in Polygon problem for a piece of commercial software. I solved it invoking the ray casting algorithm. After a variety of enhancements ...
29 views

### Algorithms to convert 2D videos to 3D ones

Are there published algorithms that can convert 2D videos to 3D ones? If there are few published algorithms for this I am also interested to know how the conversion quality is.
62 views

### What is the worst case time complexity for intersection tests with BVHs?

This question is in the context of computer graphics. We have a scene with $n$ triangles and a ray. We want to find if the ray intersects any triangle and get the closest one. There is a ...
52 views

### Research in realtime computational physics?

I am aware that there is a considerable amount of interest in computational mechanics for simulation of cloth, hair and other elastica, particularly for animation films. The methods developed by ...
75 views

### Segmenting a human body point cloud into limbs

I have a human body point cloud taken through a Kinect (v1). Now, I want to segment the point cloud into different parts, namely hands, lower arms, upper arms, torso, upper legs, lower legs, feet and ...
12 views

### Probable focal point of a set of rays

Given a set of two-dimensional rays, how can I determine the probable focal area of the rays? For simplicity, assume a circle focal area. Imagine a number of people throwing paper airplanes at a ...
53 views

### Image Comparison tuned to Human Perception

Say I have two systems that take the same drawing commands and starts drawing on their respective platforms (i.e. HTML Canvas). After this is done, I want to save and compare these two images to ...
129 views

### Why are division/floating points inefficient in comparison to integer addition/multiplication/subtraction?

Why does Bresenham's line algorithm eliminate dy/dx division and the multiplication of that (potentially floating point) number?
45 views

### How do I output a single pixel on the monitor using assembly language? [closed]

I want a low-level understanding of how a pixel is displayed on a monitor. I am guessing that the point at which I want to display a pixel must be modified in the frame buffer, which should be sent ...
180 views

### How does the Sutherland-Hodgman Algorithm work?

The following are the Pages-96 and Page-97 of the book Schaum's outline series of Computer Graphics. The algorithm considers several things: (1) Whether the polygon is Convex or Concave. (2) ...
210 views

### Computing the number of squares which are intersected by a line internally

There's a line from (x1,y1) to (x2,y2) in a grid of squares of unit length. Write a program to compute the number of squares which are intersected by the line internally, i.e squares which are only ...
417 views

I was just wondering on a more technical side, if anyone could explain what Google does to create these amazing images from it's deep dream system. Could anyone explain to me in a step by step way, ...
91 views

### Most Efficient Method To Determine Triangle Fill Values Based On Corner Values

I have a triangle and the value of the pixel intensity at each of the three corners of the triangle. I want to interpolate to find interpolated pixel intensities for a set of points inside the ...
98 views

### How to expand 2D graphic and functions to 3D?

So I have a program that enables the user to draw 2D-objects. To rotate them, to move them, and so on, all in 2D. I want to expand the 2D objects and functions to 3D which I don't expect to be too ...
69 views

### What's the difference between all these terms?

What's the difference between them - Physically based simulation, Physically based animation, Physical simulation for computer animation, Physically based animation for Computer graphics, Physically ...
77 views

### What are some interesting applications of the skyline problem?

You are given a set of $n$ rectangles in no particular order. They have varying widths and heights, but their bottom edges are collinear, so that they look like buildings on a skyline. For each ...
22 views

### 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 ...
135 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 ...
87 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 ...
97 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 ...
18 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 ...
127 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 ?...
82 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: ...
167 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 ...
148 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 ...
44 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 ...
35 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 ...
113 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 ...
273 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 ...
67 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?
2k 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 ...
47 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,...
190 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 ...
302 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 ...
399 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' ...
1k 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 ...
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?
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 \...