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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 ...
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. ...
• 1
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### 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 ...
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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 ...
• 341
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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: $$(0,...,0,...,1,...,1)$$ ...
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(...
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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. ...
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). [...
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### 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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### 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 ...
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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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1 vote
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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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### 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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### 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 ...
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....
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### 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 ...
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1 vote
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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
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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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### 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 ...
1 vote
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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 ...
1 vote
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 ...
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 ...
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1 vote
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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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### 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 ...
1 vote
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. ...
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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. ...
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 ...
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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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1 vote
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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
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### 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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### 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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### 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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1 vote
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 ...
1 vote
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 ...
1 vote
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 ...
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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.
1 vote
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 ...
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### 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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1 vote
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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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1 vote
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### 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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### 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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### 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 ...
• 155
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 ...
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1 vote
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 ...
• 155
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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 ...
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,...
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### 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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### 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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1 vote