Computer Graphics Stack Exchange
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Why are normal maps blue and purple in color?

I am learning about normal mapping. I understood that RGB values are converted into XYZ, but my question is how is it converted and why is the normal map blue and purple in color?
Abhinay Singh Negi
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Should the alpha channel be gamma corrected

We know that in PNG,BMP,etc... the pixel value stored is not in the linear RGB space. But I found no document saying anything about the alpha channel. Is the alpha channel stored in image files in linear space or not?
Mary Chang
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What are Spherical Harmonics & Light Probes?

What are Spherical Harmonics & Light Probes? How useful are they in computer graphics? What exactly do they do? I've heard the word spherical harmonics & Light Probes everywhere, from siggraph presentations to blog posts. Recently Matt Pettineo…
Arjan Singh
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Data structures for tile-based (deferred) rendering

Tiled rendering is used in modern mobile GPU architectures to increase the coherency of memory access by subdividing image space into a regular grid of small (e.g., 32x32 pixel) tiles. Information is scarce on the types of data structures used to…
warrenm
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Why is recursion forbidden in OpenCL?

I'd like to use OpenCL to accelerate rendering of raytraced images, but I notice that the Wikipedia page claims that recursion is forbidden in Open CL. Is this true? As I make extensive use of recursion when raytracing, this will require a…
trichoplax is on Codidact now
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How is VR different from a monitor

Apparently Macintosh computers cannot handle the Oculus Rift, because of their 'inferior' graphics cards. But should VR not just be like an external monitor? And concerning computer graphics, how are VR games any different from other games the…
Hans
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What is Tessellation in computer graphics

In recent games I have noticed something called Tessellation, Turning the thing ON destroys my frame rate. I have noticed that it when turned on it looks like Anti - Aliasing. Can someone give me further information on what exactly the GPU does.
Anarach
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3 answers

Difference between rendering in OpenGL and 3D animation software

With OpenGL and such I can render some pretty amazing looking things in "real time" 60 FPS. However, if I try to make a video of that same scene in let's say Maya, or 3ds Max it would take MUCH MUCH longer for it to render even though it is the…
J.Doe
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What's the current state-of-the-art algorithm for ray-tracing height-fields?

There have been lots of papers over the years on different techniques for drawing height-field terrain in a ray-tracer. Some algorithms ray-march the grid directly (or via a quadtree); others transform the terrain into a polygon mesh and use a…
Dan Hulme
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Is there any way to generate primitives in a geometry shader without any input geometry?

A few years ago I tried to implement this GPU Gem in OpenGL to generate 3D procedural terrain using Marching Cubes. The article suggests to implement Marching Cubes in a geometry shader to maximum efficiency. This means I need to run the shader once…
Martin Ender
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GL_STATIC_DRAW vs GL_DYNAMIC_DRAW vs GL_STREAM_DRAW: does it matter?

In OpenGL the buffer object functions (glBufferData, glBufferSubData, and probably a few others) have a parameter usage, described by the documentation as a hint of the intended usage, likely meant to help the implementation yield better…
Julien Guertault
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Progressive Path Tracing with Explicit Light Sampling

I understood the logic behind the importance sampling for the BRDF part. However, when it comes to sampling light sources explicitly, all becomes confusing. For example, if I have one point light source in my scene and if I directly sample it at…
Mustafa Işık
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What does "makeContextCurrent" do exactly?

I am pretty confused about that function. GLFW Context reference says as follow: This function makes the OpenGL or OpenGL ES context of the specified window current on the calling thread. A context can only be made current on a single thread at…
Adrian
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Physically based shading - ambient/indirect lighting

I implemented a physically based path tracer after studying PBRT by M. Pharr and G. Humphreys. Now I'm trying to apply physically based rendering to real time graphics using OpenGL ES (in an iPhone application). I want to start using Oren-Nayar and…
Fabrizio Duroni
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benefit of perlin noise over value noise

While investigating the inner workings of perlin noise, I wondered why one would use perlin noise instead of simple value noise. As far as I understand it right, the following applies: Perlin noise is a lattice based noise function, which assigns a…
Timm
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