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Questions tagged [physics]

The tag has no usage guidance.

0
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0answers
8 views

Stacking vertex rotations around different axes of rotation

I have a binary tree, each node being a vertex with a 3D coordinate. I have to traverse the tree in a way to rotate each child node around an axis going through it's parent. The catch is that every ...
1
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1answer
90 views

Why are BRDF and the lighting uncorrelated?

In relation to this question, in the accepted answer I have a trivial question probably. W.r.t. the following integral $$ L_o(x\rightarrow \Theta) = \int_{\Omega_x} f_r(x,\Psi\rightarrow\Theta)L_i(x\...
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2answers
83 views

Why is the approximation valid, in the formula provided by Brian Karis?

I'm sorry I'm bringing this topic up again, but I need to expound some of the topics. With reference to this question, I was wondering if someone can help me out in expanding some of the details. In ...
1
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0answers
27 views

Spring damping in Energy Function

Supposing a behavior function $C(x_1, \ldots, x_n)$, then we have a scalar potential energy function $E = \frac{k_s}{2}C\cdot C$ where $k_S$ is stiffness constant. Hence, the force is as follows $...
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1answer
214 views

Hooke's Law vector form

I'm studying spring model. There is a suggested equation (Hooke's Law vector form) But, I couldn't understand how to derive that equation. I'm reading 'Computer Animation Algorithms and Techniques ...
1
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1answer
235 views

Beginner CG Research Project [closed]

This summer I will be working with a professor on a research topic of my choice, in the field of graphics & simulation. While my professor is knowledgeable in the area he is being very hands off ...
11
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3answers
790 views

What explains the high specularity of metals?

From my understanding, the specular color usually refers to the amount of light that is reflected when the surface is lit at normal incidence, and is noted $F_0$ or $R_0$. Moreover, for non metal ...
5
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1answer
177 views

Creating Sparks using Code

I'm new to this area and have less knowledge. I want to create some graphics like sparks and lightning by writing some code, using my own physics. I don't want to use some engine, However I can use ...
3
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0answers
75 views

What is a good algorithm, and framework, to calculate centres of gravity or mass (cog)?

I'd like to take an photograph, subdivide it into a tesselation, either of squares, or (ideally), hexagons, and then find the centre of gravity (or, if you prefer, centre of mass) of each cell of the ...
5
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1answer
393 views

Can we use PhysX in WebGL?

I'm new to GL stuff (coming in via WebGL, with no direct OpenGL experience). Can we use PhysX with WebGL?
9
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2answers
282 views

Total emitted power of diffuse area light

I am reading the book Physically Based Rendering (Pharr, Humphreys). In the chapter on lights, they talk about approximating the total emitted power of different kinds of lights. For example, a point ...
1
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1answer
45 views

How would I create a virtual cabling system?

I am trying to devise a GUI system that functions as a virtual patchbay, as seen in something like Logic Studio's environment editor, or seen in virtual synthesizers that use virtual patchcables. I'm ...
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4answers
375 views

What physical properties are “lacking” to keep this 3D scene from looking like a real photograph?

So I know that I'm basically asking to identify the main problem to be solved in creating realistic 3d Graphics, but as someone without much technical experience in the field, I'm curious that if ...
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2answers
199 views

What is the effect of the BRDF denominator?

I was reading a paper on BRDF. I've come across this formula : $$ f(\omega_i, \omega_o ) = \frac{FDG}{4(N.V)(N.L)}$$ The (N.L) term can be cancelled by the cosine term which appears in the rendering ...
7
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1answer
641 views

Resulting Probabilty Density in Path Tracer for paths using Next Event Estimation

I am trying to implement my own Gradient Domain Path Tracer by following the code of this guy who already implemented it: https://gist.github.com/BachiLi/4f5c6e5a4fef5773dab1 I already managed to ...
7
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5answers
281 views

Why does the 1/r² term appear with point sources?

I'm currently reading some books on radiometry. They mention that radiance is constant along a ray. It doesn't change with distance. However, I've seen some raytracer and they put the 1/r² factor when ...
7
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1answer
1k views

What's the difference between irradiance and fluence/radiant exposure?

A paper$^1$ I'm reading says fluence measures the incoming radiance from all directions and that fluence is similar to irradiance. It's defined by $\phi(x) = \int_{4 \pi} L(x, \vec{\omega'}) d\omega' $...
13
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2answers
469 views

Fresnel reflectance of gold: red channel greater than 1?

I've been trying to understand some of the physical principles behind light and material interaction lately. In his talk Physics and Math of Shading, Naty Hoffman explains Fresnel reflectance and ...
9
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1answer
172 views

How could I check the correctness of my result of fluid simulation?

I wrote a particle based fluid simulating program. It's hard to tell if I get the right result. The visualized result seems reasonable, but some part of it looks weird. I don't know wether it's a ...
30
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2answers
3k views

How physically-based is the diffuse and specular distinction?

The classical way of shading surfaces in real-time computer graphics is a combination of a (Lambertian) diffuse term and a specular term, most likely Phong or Blinn-Phong. Now with the trend going ...
12
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2answers
840 views

How to build a decent lens/camera objective model for path tracing?

I have written a small path-tracer after learning and experimenting on smallpt. The only thing that I did not write (and understood) myself is how the initial rays are computed and fired from the ...
7
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2answers
119 views

Overlaying graphics on particle simulation

How can I overlay graphics on particle simulations? For instance if I am representing a liquid or gas with tons of little points how can I make those points look like a liquid or gas? Take Nvidia Flex ...