Questions tagged [graphics]
The graphics tag has no usage guidance.
54
questions with no upvoted or accepted answers
6
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answer
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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 ...
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4
votes
0
answers
108
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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:
...
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3
votes
0
answers
109
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Algorithm to count number of overlapping rectangles of the same colour?
Say you have a grid of pixels. And there are 20 overlapping red rectangles on a blue background.
I want to find an algorithm to count the minimum number of rectangles that are needed to form the image....
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3
votes
0
answers
72
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area of the projection of a mesh
Given:
a quadrilateral mesh that forms the surface of a sphere
a linear projection from 3D to 2D (a 2x3 matrix)
The mesh is not convex in general, but it is regular enough
that we know that the ...
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3
votes
0
answers
169
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Is it possible to simulate/emulate non-euclidean geometry using computer graphics?
I am aware of the frequent use of "smoke and mirrors" in order to achieve the effect of non-euclidean geometry, but I was wondering it if it possible to implement spherical (sometimes called elliptic) ...
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3
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0
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699
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Available algorithms for drawing (filled) Bézier paths
There are plenty of libraries around allowing to draw Bézier paths, but not that much information about how to implement one of those libraries.
The question is: What algorithms are used for drawing ...
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3
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0
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33
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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 ...
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3
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0
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546
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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 ...
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3
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0
answers
217
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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 ...
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2
votes
0
answers
104
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A Single Row GUI Layout Algorithm
I need a layout algorithm and use it in the GUI, but I can't use existing GUI toolkits at the moment, so I would like to find a layout algorithm.
I only need to do a single row layout, and here is the ...
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2
votes
0
answers
389
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Semi-automatic layout algorithms for a mind map
There're some existing tree layout algorithms such as Tidier Drawings of Trees and Drawing Non-layered Tidy Trees in Linear Time. I call them as automatic layout algorithms since positions of nodes ...
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2
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0
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195
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Sugiyama's algorithm: ambiguity in Barycentric Method for arc (edge) crossing reduction?
Context:
This question rises from the paper "Methods for Visual Understanding of Hierarchical System Structures" by Kozo Sugiyama, Shojiro Tagawa and Mitsuhiko Toda, which lays out a framework (the ...
- 121
2
votes
0
answers
355
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Modified Sutherland Hodgeman Algorithm
I'm familiar with applying the sutherland hodgeman algorithm for convex polygons(and even concave polygons with a slight modification) against convex clipping windows.
However, if I am to modify the ...
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,...
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1
vote
0
answers
26
views
Polygon union with arcs
I have two non-convex polygon which intersect one another. I have written program years ago to find union polygons. I described that I has been used algorithm Weiler-Atherton. But in Wikipedia I found ...
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1
vote
0
answers
123
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Distance between two points on 3D Triangular Mesh Manifold
I'm working on my bachelor thesis (on Computer Science) and right now I'm having a problem about finding shortest path between two points on 3D triangular mesh that is manifold. I already read about ...
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1
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0
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27
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Origin of GUI terminology
I'm wondering where the GUI terminology like modal dialogue comes from.
Who first used these terms? Is there a paper or a book, or was it just sw?
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1
vote
0
answers
16
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Triangular Rasterisation with Barycentric Coordinates
I'm having trouble with a pretty basic function that tests whether or not a point is inside of the triangle by trying to find its barycentric points with 2 other points on the triangle. When i run my ...
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1
vote
0
answers
70
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Using Marching Squares to connect curve ends in adjoining squares
I'm learning Marching squares for a graphic program I'm working on and, while I understand how to connect points along an edge of a single square depending on the vertex values, I am unclear about how ...
1
vote
0
answers
149
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Where is the epipole if one camera center is not in view of the other?
In the book multiple view geometry, the epipole is defined as follows:
The epipole is the point of intersection of the line joining the
camera centres (the baseline) with the image plane. ...
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1
vote
0
answers
109
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Algorithm or Method to reconstruct 3D world coordinates from 2D pixels with some known corresponding real-world dimensions
I have an algorithm than can recognize the 2d pixel locations of certain 3d points within a 2d image. Ultimately we are interested in computing a real-world horizontal distance between these points. ...
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1
vote
0
answers
19
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Convert Subdivision Curve to Bezier Curve
Wondering if there is a way technically to convert a Subdivision Curve into a Bezier Curve.
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1
vote
0
answers
31
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How to register an articulated model to noisy predictions?
Given point sets $Y$ and $M$, I'd like to register articulated $M$ to $Y$ without changing the edge distances of $M$. The point correspondences between $Y$ and $M$ are known and points have a fixed ...
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1
vote
0
answers
125
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What areas of geometry are used in computer graphics?
I've taken intro to graphics and am interested in diving deeper into the subject. My understanding is that the field depends a lot on geometry, but I'm having trouble figuring out exactly what ...
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0
answers
22
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Given a JPG of a wallpaper, how can I find the smallest section which contains the pattern?
I recently made the photo
of tapestry, but I am not able to identify the smallest patch which contains the pattern.
Now I wonder: How could I write a program that does so?
A first step could be ...
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1
vote
0
answers
113
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Why is the scan line filling algorithm for computer graphics so complicated?
It seems to me that the algorithm is over complicated.
It makes use of tables, buckets, and sorting, which all seem unnecessary.
I don't understand why I can't just fill between pairs of scan line ...
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1
vote
0
answers
76
views
How to detect if objects are on top of each other?
Lets say we know the co-ordinates of each object in a camera co-ordinate systems. How do we find out if some object is on top of each other? My idea is: Compare each object and point with one another....
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1
vote
0
answers
294
views
Number of colors in frame buffer
I don't know how to solve this. The main thing I do know how buffers work but I don't know about display locations and lookup tables.
A color frame buffer has 3 bits per display location and 6 bits ...
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1
vote
0
answers
50
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 ...
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1
vote
0
answers
125
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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, ...
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1
vote
0
answers
96
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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 ...
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1
vote
0
answers
50
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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 ...
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1
vote
0
answers
55
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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 ...
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1
vote
1
answer
212
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A problem about the midpoint ellipse algorithm
I have read the book "Computer Graphics with Open GL" (Hearn, Fourth Edition) recently. However, when I read the midpoint ellipse algorithm, the following example in the book is confusing me:
For ...
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1
vote
1
answer
141
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Translating between coordinate systems
Let's say I needed to render an image at 1920 x 1080 and also at 1024 x 768. Instead of drawing two separate images, it might make sense to draw the scene in a common "virtual" coordinate system and ...
- 141
0
votes
0
answers
21
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better ways to integer interpolation?
I made some code about "integer interpolation" for running approximate alpha blending at FPGA which have low quantities of logic gate.
Let's refer to "II" as integer interpolation.
...
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0
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0
answers
21
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Algorithm for computing the vertices of a polytope defined as the intersection of half spaces
There's a very similarly sounding question with an answer already, but my setup is very, very different.
You are given $k$ half spaces in dimension $d$, defined by a point and a direction. You want to ...
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29
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NURB Sphere surface degree elevation and knot insertion
The code for degree elevation of curves in The NURBS Book by Les Piegl and Wayne Tiller pages 206--209(The_NURBS_Book) assumes the knot vector for the curve is given as:
$$(0,...,0,...,1,...,1)$$
...
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0
answers
41
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Convert NURBS surface into Cubic Bezier Surface
The following post discussed how to convert(approximate) NURBS curve into cubic Bézier curve:
Convert NURBS curve into Cubic Bezier Curve
I am trying to come up with an algorithm that converts(...
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0
answers
39
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How to make a GUI for first-order logic representation?
This idea blows my mind, I would appreciate for any guidance. In essence, the question is how a machine should work to transform any kind of formal logic into its graphical representation (e.g. ...
0
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1
answer
145
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What is this question actually asking for me to solve?
(15 marks) Suppose a ray comes from a point (2, 8) and hits at mirror point (6, 6). Assume
that perpendicular vector a point (6, 6) is 𝑛̅= (0, 3). Find the reflection emitting point from
(6, 6).
[...
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0
answers
16
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Why are point clouds useful for large datasets of geometries?
In my computer graphics course I came across this "pro" for point clouds:
Useful for large datasets (>> 1 point / pixel)
I'm trying to wrap my head about it, I know drawing is ...
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327
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Write/Read data to/from VRAM
My understanding of how a GPU works is kinda solid I think.
This is what I understood searching on the Internet:
VRAM (or framebuffer) stores what you see on screen.
Most of what the GPU does is ...
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640
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Are point clouds faster to render than triangle meshes? What are the advantages of using one over the other?
I searched online but I couldn't find any comparison between rendering a point cloud and rendering a triangle mesh.
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Adaptive Subsampling Bilinear Interpolation in Screenspace
The test-object is a signed distance function that is computed with ray-marching. When the ray hits an object the intersection-flag is set to 1 or otherwise set to 0. To speed up the process (since ...
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0
answers
383
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Alpha Blending (?) of RGB colors
I've got a theoretical exercise at my university which belongs somewhere between alpha blending and ray casting – to be honest, I’m not sure. It says, that we are looking at a voxel (1-centimeter ...
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53
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How to prevent moire artifacts in this light casting algorithm?
I am writing a 2D light casting algorithm with OpenGL compute shaders.
The algorithm is simple:
For each light source shoot out light rays from it, the ray begins at the light coordinates, it ends at ...
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0
answers
74
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Math behind path tracing
I seem to remember seeing somewhere (many years ago) a writeup of the math behind calculating the outline of Metafont glyphs. The basic idea is you have a "pen" that is a circle or oval, that you ...
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0
answers
176
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Reversible 2D Shape Descriptor
This is a research problem and I am just wondering if there is any already existing answer in any computer vision related paper that may have skipped my notice since this is not my active area of ...
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answers
365
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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,...
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