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Questions tagged [graphics]

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7 views

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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1answer
15 views

Algorithm for blending/merging shapes together like liquid

This is a basic example of how 2 circles would come together: A more complex example would be an arbitrarily shaped polygon like a country on earth, merging with another one or a circle. All of the ...
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1answer
19 views

How to find the angle of an arc to draw graphic

I would like to draw an arc from a specific point to a goal point, during the process of drawing a larger path. I would like to do it using bezier curves, which aren't adequate for modeling circular ...
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1answer
23 views

Convert NURBS curve into Cubic Bezier Curve

From this: Maybe you already know this, but it's impossible to convert nurbs to bezier splines exactly because nurbs are rational functions, and bezier splines are polynomials. I don't understand ...
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0answers
27 views

How much of the x86 instruction set does blender use? [closed]

I'm trying to better understand benchmarks that are commonly used for computer hardware. I've been unable to find an answer to this question. Extra credit if you can provide a breakdown in ...
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1answer
49 views

What is the relation between Computer Graphics, Discrete Geometry, and Complexity Theory?

I am a master computer science student, and I am interested in both geometry and complexity theory. So I would like to know what is the relations between discrete geometry, computer graphics, and ...
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0answers
27 views

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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24 views

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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28 views

Is there ongoing research on Markov Chain Monte Carlo algorithms (other than Metropolis-Hastings) for use in ray tracing? [closed]

Metropolis Light Transport is an application of the Metropolis-Hastings algorithm. Its variants differ only in the used "mutation strategy". Is there ongoing research on other Markov Chain Monte ...
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1answer
35 views

Why strokes are treated differently than fills in modern graphics pipelines

This article shows some of the issues. But basically, on the web, you have fillStyle and strokeStyle, and in WebGL you have ...
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0answers
33 views

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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2answers
46 views

How does RAMDAC get notified about framebuffer write?

I'm learning computer graphics, and I read this course lecture in order to understand how graphics I/O works under the hood. But the following explanation was not very clear to me: The values in ...
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1answer
40 views

How curves are represented in a computer

I am confused now (in thinking about limits and continuity) how curves are represented in a typical modern computer. Curves are "continuous" in that there is no discrete change from one angle to the ...
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1answer
319 views

What is the difference between luma and luminance?

I understand the following (correct me if I'm wrong): Statements Luma as the weighted sum of RGB gamma corrected components, but luminance is the weighted sum of RGB linear components. The gamma ...
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1answer
21 views

Is z-buffering the same as rasterization?

I understand z-buffering as being "object-first" in contrast to "pixel-first" since the for loop starts with checking each triangle in the scene rather than each pixel. However, is this the same as ...
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1answer
37 views

Is Phong shading a pixel-first computational model?

Wikipedia says that: If a mesh covers more pixels in screen space than it has vertices, interpolating colour values from samples of expensive lighting calculations at vertices is less processor ...
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0answers
29 views

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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1answer
46 views

How to solve a polynomial of the form y = ax^3 + bx^2 + cx + d using the incremental algorithm in computer graphics

I am studying Computer Graphics and need to design an incremental algorithm for solving the polynomial $y = ax^3 + bx^2 + cx + d$, and then implement that in OpenGL. The input will be the values of $a,...
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1answer
40 views

UV Projection of 3D shape onto 2D images

Given a 2D image of a human face and the corresponding 3D shape, how do I project the shape onto the images to extract texture patches from them to form a partial UV map?
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1answer
109 views

How can I efficiently plot the inside of an ellipse?

I am given the the coefficients for an ellipse in the form: $$Ax^2 + Bxy + Cy^2 + Dx + Ey + F=0.$$ I have a 2 dimensional array of point objects (in Python) called "pixels", and I need to give each ...
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0answers
19 views

How China's Weibo deleted text from my video? [closed]

I made a home 45 min video of myself giving a presentation on a physics topic using my iphone 6. The format is quicktime .MOV - about 2.8 GB. I converted it to .mp4,down to 650MB,using a software ...
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0answers
17 views

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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1answer
28 views

Labeling a limited number of points on the screen

I have a map with up to thousands of points on it. Now I want to label those points on the screen. But this would only make sense for a limited number of points and the label of points close by ...
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0answers
133 views

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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0answers
131 views

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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0answers
38 views

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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1answer
90 views

compute a gradient with “minimal” colorstops from a ordered set of RGB colors

I got a array of colors that are closely related = most of the time there is no sharp transition between color[n] and color[n+1]. Exemple of such an array of colors [0,.1,.2,.3,.4,.5,.6,.7,.8,.9,1.0,...
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2answers
79 views

Are there any hash functions/stateless RNGs that do not use XOR, but produce good quality visual randomness?

I'm looking for a small function from integers to integers - in a language that only has floats - that can act as a visual RNG. Normally I would use a function such as the one described here: ...
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0answers
47 views

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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0answers
94 views

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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0answers
217 views

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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1answer
285 views

An algorithm to find the area of intersection between a convex polygon and a 3D polyhedron?

Suppose I have a set of points in 3D which are all co-planar, and which describe the vertices of a convex polygon. I know the coordinates of all of these vertices, I know the unit normal to the plane ...
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0answers
67 views

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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0answers
100 views

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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1answer
40 views

Iterate over each cell of a grid through whose interior a given line segment passes

Let $a,b>0$ and suppose we have divided the domain $\Lambda:=[0,a]\times[0,b]$ into a grid of width $n_x$ and height $h_y$. We enumerate the grid from bottom to top and left to right. Given $(x_0,...
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1answer
97 views

Rotation matrix between two objects - alignment

I am trying to align two objects based on the notion of points and their correspondence, but struggling to find a solution. I have two objects A and B. However, they are rotated in a different ...
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0answers
50 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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0answers
88 views

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 ...
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1answer
48 views

Constructing a Pixel Image from Rectangles and Row or Column Rotations

The most recent challenge on Advent of Code involves constructing an image in a binary pixel array from a sequence of instructions: rect AxB, which sets all of the pixels in a rectangle A pixels wide ...
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129 views

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 ...
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0answers
75 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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1answer
473 views

Finding all faces in a wireframe mesh

I'm trying to find an algorithm for finding all faces in a wireframe mesh. Wireframe means only the vertices and edges are given as input. There is no restriction on the number of edges a resulting ...
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1answer
83 views

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 ...
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1answer
84 views

Is there any good way to judge whether the rectangle is inside the point cloud? [closed]

How to judge whether a rectangle in the figure is inside the given point cloud? For example, in this figure, the red rectangle is outside the point cloud and the green rectangle is outside the point ...
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1answer
27 views

Why on board graphics is unfit for gaming/rendering? [closed]

What is the difference between a dedicated GPU and an integrated one?
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0answers
131 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,...
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1answer
75 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 ...
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2answers
37 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 ...
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2answers
1k 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 ...
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4answers
3k 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 ...