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Questions tagged [graphics]

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how to 3d render with only drawing pixels

I have been trying to find ways to display a 3d scene on a screen (specifically 480x240px Vex robotics brain). The only ways that I can draw to the screen is with drawing individual pixels or with ...
RBLX Reid's user avatar
0 votes
0 answers
24 views

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. ...
박성재's user avatar
4 votes
2 answers
546 views

Detecting if an edge is "inside" a polygon?

I have computed a constrained triangulation of a set of points. The constraint happens to be a closed polygon. The objective is to detect all edges which are inside the polygon, that is, an edge where ...
Makogan's user avatar
  • 341
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0 answers
21 views

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 ...
Makogan's user avatar
  • 341
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0 answers
29 views

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: $$(0,...,0,...,1,...,1)$$ ...
John He's user avatar
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0 answers
43 views

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(...
John He's user avatar
0 votes
0 answers
39 views

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. ...
Danila Nikolaychuk's user avatar
0 votes
1 answer
145 views

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). [...
Kaleb's user avatar
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-1 votes
1 answer
42 views

matplotlib.widget.Slider displays but isn't active when plt.show() is called outside function that created the slider. Am I missing something?

...
Norman Whitehead's user avatar
1 vote
0 answers
32 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 ...
Saku's user avatar
  • 141
2 votes
2 answers
415 views

Is there a working O(1)-space flood fill algorithm?

This is a purely theoretical question: among the known flood fill algorithms, there is one which does not require any dynamically-sized data structures, explicit or implicit: the so-called Walk-based ...
Leo B.'s user avatar
  • 133
2 votes
0 answers
109 views

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 ...
skiars's user avatar
  • 21
1 vote
0 answers
127 views

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 ...
Patrik Bašo's user avatar
0 votes
0 answers
16 views

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 ...
Oli's user avatar
  • 101
4 votes
1 answer
164 views

BVH construction without sorting

Common algorithms for creating bounding-volume-hierarchies (BVH) rely on grouping primitives together that are not necessarily adjacent in memory. This is either done by rearranging the primitives ...
thessalchips's user avatar
3 votes
0 answers
111 views

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....
zooby's user avatar
  • 263
2 votes
1 answer
188 views

Bresenham's line drawing algorithm guarantees

I am considering implementing my own version of Bresenham's line drawing algorithm, found here, my one question is does the algorithm guarantee that both endpoints will be covered/drawn. I am doubting ...
yosmo78's user avatar
  • 187
1 vote
0 answers
27 views

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?
Tomas By's user avatar
  • 111
1 vote
1 answer
214 views

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 ...
HZ-VUW's user avatar
  • 111
0 votes
2 answers
516 views

Interpolation: How to generate 3D objects from 2D cross-sections?

Consider a sphere sitting on an $xy$-plane, and take 2D slices parallel to the $xy$-plane at various heights of z. Suppose we take 10 slices, evenly spaced along the $z$-axis, and now have 10 images ...
colmor's user avatar
  • 1
1 vote
0 answers
16 views

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 ...
Savon Brown's user avatar
1 vote
0 answers
71 views

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 ...
MinorMapillai's user avatar
4 votes
1 answer
56 views

Detecting rotational symmetries of spatial structures

I have a spatial graph-like structure. The structure consists of vertices in the 3D space and connecting edges. Are there any algorithms available that would identify the rotational symmetries of ...
Botond's user avatar
  • 143
1 vote
0 answers
150 views

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. ...
Ralff's user avatar
  • 163
0 votes
0 answers
329 views

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 ...
Diego's user avatar
  • 1
1 vote
0 answers
109 views

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. ...
WiseDev's user avatar
  • 11
0 votes
1 answer
26 views

Are graphic cards using the Map-Reduce model when performing typical gaming rendering

I know that the Map-Reduce model is a common model of parallel computation, perhaps some sort of standard way(?). I also know that graphic cards are specifically built for parallel computation. ...
Niteraleph's user avatar
3 votes
1 answer
209 views

Complexity of "Fast Poisson Disk Sampling in Arbitrary Dimensions"

I came across the paper Fast Poisson Disk Sampling in Arbitrary Dimensions which gives an algorithm for generating Poisson disk points in $\mathbb{R}^n$. It's claimed that the algorithm is linear ...
overfull hbox's user avatar
3 votes
0 answers
74 views

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 ...
Glenn Davis's user avatar
1 vote
0 answers
19 views

Convert Subdivision Curve to Bezier Curve

Wondering if there is a way technically to convert a Subdivision Curve into a Bezier Curve.
Lance's user avatar
  • 2,243
1 vote
2 answers
493 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 ...
Lance's user avatar
  • 2,243
0 votes
1 answer
56 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 ...
user10869858's user avatar
3 votes
1 answer
2k 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 ...
Lance's user avatar
  • 2,243
1 vote
0 answers
52 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 ...
Michael Smith's user avatar
1 vote
1 answer
185 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 ...
husseinhoudrouge's user avatar
1 vote
0 answers
31 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 ...
mkocabas's user avatar
  • 111
0 votes
0 answers
649 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.
Christian Pao.'s user avatar
1 vote
0 answers
52 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 ...
0xbadf00d's user avatar
  • 217
1 vote
1 answer
43 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 ...
Lance's user avatar
  • 2,243
1 vote
0 answers
126 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 ...
lightning's user avatar
  • 225
1 vote
2 answers
279 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 ...
user6039980's user avatar
2 votes
1 answer
344 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 ...
Lance's user avatar
  • 2,243
10 votes
2 answers
7k 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 ...
winnie99's user avatar
  • 155
0 votes
1 answer
382 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 ...
winnie99's user avatar
  • 155
1 vote
1 answer
74 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 ...
winnie99's user avatar
  • 155
0 votes
0 answers
71 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 ...
Natural Number Guy's user avatar
0 votes
1 answer
597 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,...
swdeveloper's user avatar
2 votes
1 answer
52 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?
Abhinay B's user avatar
  • 121
3 votes
1 answer
390 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 ...
Jbag1212's user avatar
  • 133
1 vote
0 answers
32 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 ...
itsme's user avatar
  • 11