Questions tagged [material]

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Questions about BRDF parameterization

Hi I'm trying to get a better understanding of the BRDF modeling. I only implemented naive diffuse(lambert), specular and microfacet BRDF before, but I don't have much experience in mixed BRDFs and ...
3
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1answer
171 views

Iridescence/Thin-film interference integration as a layer

I'm trying to integrate the thin-film interference effect described in the paper "Belcour, L., & Barla, P. (2017). A practical extension to microfacet theory for the modeling of varying ...
2
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1answer
60 views

Confused on reflection coeffcient of Fresnel equations

I am reading a paper about layered materials. However, I am confused on the implementation of this paper. The following picture describe the layered material. r_ab is a complex reflection coeffcient ...
12
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2answers
258 views

Why does graphics speak of “dielectrics” rather than insulators?

For example, Filament's documentation at https://google.github.io/filament/Filament.md.html uses the term "dielectrics" when contrasting nonconductors to conductors, which it calls "metallics". And ...
1
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1answer
80 views

Understanding material .mtl files

I am reading this piece of documentation to understand mtl files So far I am stuck trying to understand the difference between ambient, diffuse and specular reflectivity (Ka, Kd, Ks). If I am ...
1
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0answers
28 views

Proper design of data structure to store wavefront file information?

Currently I have a naive Mesh data structure to store wavefront files. This data has 3 buffers for the vertices, normals and UVs. It works well to the point I can render the sponza scene, despite ...
3
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1answer
355 views

Combine material coefficients and textures in Phong Shading

I'm trying to implement a simple Phong shader that supports non-physically-based materials and textures. Even though the material has a texture for each light component I still want the respective ...
2
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1answer
431 views

How can I implement this BSDF?

I am trying to implement a path tracer, but I have some problem. The class Spectrum is color. I implemented a mirror material like this: ...
3
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1answer
104 views

Confused about material layering

I am a little bit confused about the various flavors of material layering in both online and offline rendering. I had naively assumed (after using the Mix Shader in Cycles and a few minutes in ...
5
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3answers
8k views

What is the difference between glossy and specular reflection?

What is the difference between glossy and specular reflection? What is their relations with BRDF?
4
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0answers
202 views

Beer's law in dielectric material

I am trying to implement Beer's law according to this page in dielectric material but I am not sure have done it correctly as the image does not suggest so. The formula is: I(s) = I(0) * pow(e, ln(A)*...
2
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0answers
44 views

Would the surface of a large carbon-nanotupe structure look metalic?

CNT is a promising new material, which Wikipedia describes as such: Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have ...
5
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1answer
499 views

Loading a material via assimp

I'm writing a raytracer and I'm using the assimp library to load objects. I have an object's material specified in a .mtl file: ...
6
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1answer
612 views

How can a diffused(frosted) glass be modelled in path tracing

How can a diffused(frosted) glass be modelled in path tracing? Currently I am able to define a window poly line as a clear glass material where it transmits or reflects the ray. I am not clear though ...
1
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0answers
262 views

Is there a material table for the Cook Torrance BRDF?

Is there a material table that lists all the specific values to obtain a certain type of material (e.g: copper or asphalt) available? I found this table in the paper: A Reflectance Model for ...
4
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1answer
342 views

Phong: Real-time rendering of Metal and Plastic Materials

Using a shader that works like Phong, what would be the difference between painted Metal and plastic? I seem to remember reading in books years ago, that I no longer have access to, the following: ...
12
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1answer
658 views

Path tracer - multi layered materials and importance sampling

I'm currently trying to implement a Monte Carlo path tracer. I've done some research and it seems that a common approach to materials is to use a layered model. Something like this: When light hits ...
6
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1answer
750 views

Mimicking Blender's “roughness” in my path tracer

Recently I asked a question regarding how to mix a glossy and diffuse shader in my path tracer: Mix shader looks wrong on my path tracer. I thought it was incorrect, but a comparison between mine and ...
7
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1answer
372 views

What is the most physically accurate model of surface materials possible in computer graphics?

I am looking for theoretical and implemented models to represent surface materials in software that strives for physical accuracy. Is BRDF really the best model? What alternatives are better? Why? ...
4
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1answer
70 views

Is there a material that contributes to GI, but isn't directly visible?

I am doing renders of the inside of a room. I would like to show a "bird's eye" view of the room, from above the ceiling (outside the room), but still see the interior of the room. An easy way of ...
4
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1answer
223 views

Material Layering

So after reading this Unreal Engine 4 Documentation page: https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/LayeredMaterials/ (Which describes how to use material layering in UE4) ...
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0answers
58 views

Alias|Wavefront .mtl File “decal” Command

There are material color and texture colors (e.g. Kd 0.8 0.8 0.8 vs. map_Kd diff.png). The documentation says of this: ...
4
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1answer
148 views

Does light particle loses energy when it hits something?

I have some material which I want to represent as a collection of spheres (atoms) and a particle of light (photon). I'm firing this particle and checking for the collision against atoms. What should ...
15
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2answers
2k views

Why do most photorealistic renderers have similar material test scenes?

I notice that most photorealistic renderers have very similar material test scenes. Here are a few examples: Blender Mitsuba Vray My question is: why is this specific model / style chosen to test ...