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Questions tagged [graphics]

130 questions
19
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3 answers

Ray Tracing versus object-based rendering?

Intro graphics courses usually have a project that asks you to build a ray tracer to render a scene. Many graphics students entering grad school say that they want to work on ray tracing. And yet it seems that ray tracing is a dead field in venues…
Suresh
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15
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2 answers

Which method is preferred for storing large geometric objects in a quadtree?

When placing geometric objects in a quadtree (or octree), you can place objects that are larger than a single node in a few ways: Placing the object's reference in every leaf for which it is contained Placing the object's reference in the deepest…
nsantorello
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10
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2 answers

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 correction has two forms: gamma compression and…
winnie99
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10
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1 answer

Is the shadow ray in a Whitted ray tracer occluded by transparent objects?

In a Whitted ray tracer, each ray-object intersection spawns a transmitted ray (if the object was translucent), a reflected ray and a shadow ray. The shadow ray contributes the direct lighting component. But what happens if the shadow ray intersects…
user11171
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10
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3 answers

Intuition for convolution in image processing

I have read many documents about convolution in image processing, and most of them say about its formula, some additional parameters. No one explains the intuition and real meaning behind doing convolution on an image. For example, intuition of…
hqt
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10
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1 answer

How to find contour lines for Appel's Hidden Line Removal Algorithm

For fun I am trying to make a wire-frame viewer for the DCPU-16. I understand how do do everything except how to hide the lines that are hidden in the wire frame. All of the questions here on SO all assume you have access to OpenGL, unfortunately I…
Scott Chamberlain
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9
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1 answer

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" in R-tree is for rectangle. This seems to be a…
Martin Thoma
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7
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1 answer

Line smoothing algorithm that perserve data uniformity

Intro: I'm working with huge data set that i need to plot in browser, and since there may be up to 1M points my idea was to create different representations for different zoom levels lets say i have 100k points, i would average two-by-two until i…
Dragan B.
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7
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2 answers

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 Transform. A DCT is similar to a Fourier transform in…
Higgins
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6
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1 answer

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 too slow to be practical). For example, a very…
Archival
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6
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1 answer

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 rectangle, you’re given the $x$ position of the left…
jsguy
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5
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3 answers

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. Is this not like giant, super inefficient overkill?
Eric
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5
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2 answers

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 head. Here's the method I'm currently using: I…
Ranveer
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4
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1 answer

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 of the polygon, and I know the order (in a…
John Barber
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4
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1 answer

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 face can have and the face can be convex or…
hgs3
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