Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [shading]

72 questions
51
votes
4 answers

Albedo vs Diffuse

Every time I think I understand the relationship between the two terms, I get more information that confuses me. I thought they were synonymous, but now I'm not sure. What is the difference between "diffuse" and "albedo"? Are they interchangeable…
hmind
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18
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3 answers

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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15
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1 answer

How does state of the art real time hair rendering work?

It is common knowledge that hair simulation and rendering is particularly challenging and in fact rare are the examples in games that propose believable hairs. It is pretty easy to imagine how hard it is to actually simulate the high amount of…
cifz
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13
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2 answers

Programmatically generating vertex normals

I'm working with Kinect face api, it provides an array of vertices and indices for triangles which is to be rendered to make the face image. The no of vertices and their order in array as well as the indices given by kinect is always…
Allahjane
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13
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3 answers

Is a Lambertian reflector illuminated by a smaller fraction of the incident radiation when it's tilted?

In reading about Lambertian reflectance on Wikipedia I found the following phrase (in bold) which doesn't sound right to me: In computer graphics, Lambertian reflection is often used as a model for diffuse reflection. This technique causes all…
trichoplax is on Codidact now
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12
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2 answers

How is screen space ambient occlusion implemented?

I do not understand the explanation from wikipedia. For every pixel on the screen, the pixel shader samples the depth values around the current pixel and tries to compute the amount of occlusion from each of the sampled points. How can depth…
Joey
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10
votes
1 answer

Shading: Phong vs Gouraud vs Flat

How do they work and what are the differences between them? In what scenario should you use which one?
Joey
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10
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1 answer

Trying to implement Microfacet BRDF but my result images are wrong

I am trying to implement microfacet BRDF model. I am reading Sebastien Lagarde's slides. I implemented formulas to my code but i think result image is wrong. Yellow is base color of material. Specular color is red to see properly. My code: //…
hmkum
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9
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2 answers

What is ambient occlusion?

Ambient occlusion "is a shading and rendering technique used to calculate how exposed each point in a scene is to ambient lighting. Ambient lighting is regarding to What is ambient lighting?: ... lighting to be constant and independent from…
Joey
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7
votes
2 answers

Sampling against geometry normals

I am writing a basic raytracer and have implemented normal maps. However, when using normal maps, sometimes the rays generated are opposite to the surface's geometry normal, so that the rays are reaching light sources behind the object. If I kill…
anonymoose2121
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6
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1 answer

"Artist Friendly Metallic Fresnel" reversible?

While implementing the "Artist Friendly Metallic Fresnel" paper by Ole Gulbrandsen (http://jcgt.org/published/0003/04/03/paper.pdf), I read that it is fully reversible: (section 2.3.2): for all r,g ∈ (0,1), the map from (n, k) to (r,g) is a…
zeno
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6
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2 answers

PBR missing rim darkening on non metallic rough surfaces

If you have a dielectric (non metallic) sphere with a large roughness value (say, 0.95), and put it in a lighting environment that has a constant onmidirectional lighting value (such as 0.5) Cook-Torrance ggx PBR renderers seem to be missing a…
Alan Wolfe
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6
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1 answer

Microfacet shading for diffuse materials

I recently replaced the Lambertian BRDF in my path-tracer with Oren-Nayar, under the assumption that I could adjust it to use the GGX distribution model with appropriate masking/shadowing. PBR suggests this is't viable, though - Oren-Nayar is…
Paul Ferris
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6
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1 answer

What's the difference between geometric surface normal and shading surface normal?

In my opinion, geometric surface normal is the cross product of triangle edge vectors, and shading surface normal is the interpolation of the predefined normals at the three vertexes. I used Mitsuba to render the geometric normal channel and the…
chaosink
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5
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0 answers

Why is Forward Rendering/Shading named this way?

Forward rendering is the 'classic' approach to the rendering pipeline. Nowadays it is mostly replaced by a more flexible, deferred rendering approach. I did some research and had trouble finding something specific about the history of Forward…
LukeG
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