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1500 questions
6
votes
2 answers
How to calculate attenuation and radiance in PBR? (point and directional lights)
I would like implement physically based rendering, following this tutorial
I was able to find a list of light sources ordered by lumens, but I have no idea how to use it in the calculations.
float attenuation = 1.0 / (distance * distance);
vec3…
Iter Ator
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6
votes
1 answer
Dealing with blown-out highlights in PBR
I've been writing some custom shaders based around Unity's Standard BRDF, which is uses GGX distribution term and Smith visibility term. It looks great at either end of the smoothness scale (1 and 2 in the pic below). However, with the smoothness…
russ
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6
votes
1 answer
List of triangles to minimum amount of convex polygons
I'm in search for an algorithm that takes the left side of the following graphic as an input and outputs a minimal amount of convex polygons as seen on the right side of the graphic.
The input mesh can be very complex and could contain several…
Timm
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6
votes
1 answer
Seamless Textures
I understand how an artist would make seamless textures by hand, but how can a computer program automate that process? Software like PixPlant is capable of doing this, but I don't understand how it does this.
Daniel Kareh
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6
votes
1 answer
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 how it should work if the sheet of glass is…
ali
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6
votes
1 answer
Monte Carlo Integration
Let $I$ = the value of integration and $p$ = probability distribution.
The estimator is denoted as $\left\langle I \right >$ and is
$$\left\langle I \right >=\frac{1}{N}\sum_{i=1}^{N}\frac{f(x_i)}{p(x_i)}$$
The expected value of this estimator is…
shashack
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6
votes
1 answer
How can I verify if a selection area is over a shape in SVG?
I'm creating an SVG editor.
I have a simple selection tool that appears when I click and move my mouse from a blank area in my SVG.
My SVG is populated with rectangles that can have a rotation applied to.
I have the X and Y position applied to a…
JSmith
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6
votes
2 answers
Color transform algorithm (that also works on saturation and value/lightness)?
To change particular colors in an image, generally you multiply the RGB by a transformation matrix. Image manipulation programs such as gimp & photoshop have a selective color change function that allows a user to convert pixels within a certain…
Escher
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6
votes
1 answer
CrazyBump Shape Recognition
I've recently been using CrazyBump, and I think I'm starting to understand how it works. But I'm confused about what it calls Shape Recognition. According to this website, that feature attempts to add directional lighting information, but what…
Daniel Kareh
- 577
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6
votes
1 answer
The reciprocity of BRDF
Many books describe that a BRDF has the following property (reciprocity):
$$f_r(x, \Theta \to \Psi ) = f_r(x, \Psi \to \Theta)$$
Why is the above equation correct?
I think the above equation should be changed as follows:
(because the two symbols…
shashack
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6
votes
1 answer
What is the difference in overlay and framebuffer?
I have been trying to understand display and graphics. I feel that it's hard to make a logical image of the terms. I understand this:
Frame buffer is a dedicated memory that has the image/video/3dimage or video to be shown, in pixel format.
Overlay…
mrigendra
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6
votes
1 answer
3D projection that increases objects' size as they become more distant
tl;dr Is there a name for a type of (non-physical) projection that causes objects to become larger the farther they are from a camera?
With a fisheye projection, an object twice as far from the camera is less than half the size on screen. (I think;…
Phrogz
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6
votes
0 answers
Cascaded shadow maps. Seams between cascades
I implemented cascaded shadow maps, where shadow maps for each cascade is rendered to one canvas:
The light projections for each cascade are calculated from the bounding spheres of camera sub-frustums:
The code for calculation visibility value:
for…
Zheden
- 161
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6
votes
2 answers
What does "Bidirectional" in BRDF mean?
So Bidirectional essentially means "two directions", right? But what are these two direction (left-right? up-down? north-south?) we are talking about in regards to bidirectional reflectance distribution function (BRDF), bidirectional scattering…
Kristoffer Helander
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6
votes
2 answers
Spherical Harmonics Diffuse CubeMap. How to get coefficients?
envmap.pdf | An Efficient Representation for Irradiance Environment Maps
Spherical Harmonics and applications in real time graphics
I am using Spherical Harmonics to turn reflective(mirror like) cube map to diffuse light cube map.
From what I…
Blue Bug
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