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13
votes
3answers
2k views

Importance Sampling of Environment Maps

What is the best currently known and ideally also production-verified approach for sampling environment maps (EM) in a MIS-based uni-directional path tracer and similar types of renderers? I would ...
2
votes
2answers
653 views

How are hard and soft shadows cast?

I have been studying computer graphics, from the book Fundamentals of Computer Graphic (but the third edition), and I lastly read about texture mapping and shadow maps. Though, I didn't exactly ...
9
votes
1answer
10k views

What's the difference between orthographic and perspective projection?

I have been studying computer graphics, from the book Fundamentals of Computer Graphic (but the third edition), and I lastly read about projections. Though, I didn't exactly understand what's the ...
3
votes
1answer
74 views

Finding the maximum number of disconnected fragments

In a plane, we have a convex polygon with n sides. What would be the maximum number of disconnected pieces / fragments if this polygon is clipped against a square?
3
votes
1answer
207 views

Affine Transformation

We have a matrix $$\begin{bmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{bmatrix}$$ This matrix represents a ...
8
votes
1answer
776 views

How does everyone count “Rays per Second”?

Recently I'm developing a Monte-Carlo path tracer. To measure my tracer's performance, I decided to implement a simple mechanism to count how many rays can it trace in a second. Then here comes the ...
6
votes
1answer
827 views

How to implement Constructive Solid Geometry in ray tracing with implicit surfaces (spheres)?

What I'm trying to do is to simulate refraction through biconcave lens described by spheres A, B, ...
6
votes
2answers
106 views

Global illumination leading to image variation

I have a 3D scene I use to generate some images which I then process in Matlab. I noticed that when global illumination (GI) is not enabled, rendering always generates exactly the same pixel-for-pixel ...
3
votes
1answer
274 views

Generate this kind of 2d burst or pulse algorithm?

I'm currently trying to develop a game using Cocos2d-x using C++. I really need to generate this burst or (donut-shaped) pulse. I'm having a difficult time how to generate such shape. At first, I was ...
11
votes
1answer
336 views

What is my GPU waiting on?

I am writing an OpenCL program for use with my AMD Radeon HD 7800 series GPU. According to AMD's OpenCL programming guide, this generation of GPU has two hardware queues that can operate ...
3
votes
2answers
482 views

Line segments overlapping

I have implemented line segments intersetion test and at the very same test I want to include the fact that if two line segments overlap each other partially or fully , it will be flagged as no ...
1
vote
0answers
512 views

Line segment intersection test and find the point of intersection

Thanks for the suggestions. Now I am doing it as follows: First off it is identified if two line segments intersect or not. And I am using the algorithm described in the book - "Introduction to ...
1
vote
1answer
128 views

How can I resize a rendered ray traced image?

Say I have rendered an HDR ray traced image with dimensions 1920x1080 (width x height) pixels and I want to instead represent it with dimensions 960x540. Assume as well that the image has not yet been ...
3
votes
1answer
326 views

Data structure and algorithm for clipping triangulation with leaf nodes of an octree

I have an application in which I am using an octree to store a volume mesh of axis-aligned bounding boxes (AABBs). Given a water-tight manifold triangle mesh, I need to: find if an AABB is ...
7
votes
1answer
283 views

Gamma setting in games - Why 3 icons?

Whenever I try to adjust gamma settings in a game, I am shown three different icons and usually asked to make sure the left-most one is barely visible. Example: What are the other two icons for?
3
votes
0answers
162 views

Creating an Object Orientated Bounding Volume

I'm attempting to test out the maths behind bounding volume algorithms (prior to ray tracing) using MATLAB. So far, I have successfully created the relatively trivial axis aligned bounding volume, ...
8
votes
1answer
174 views

Find the longest straight line between two points on surface of polygon

My shape is a slightly concave polygon, and I'd like to know the maximal diameter. I imagine a straight line between two points on the surface of the polygon, such that the line does not pass outside ...
11
votes
2answers
2k views

What kind of technology would be involved in the rendering of human nails?

There are many references related to the physically-based rendering of several natural features of the numan body, such as skin, hair, eyes. However, I could not find specific information about the ...
3
votes
0answers
813 views

Represent vector with arrow

Another code review question. I am trying to draw an arrow to represent a vector. I have started with an unit arrow with vertices defined as follows: ...
2
votes
0answers
310 views

Can't render multiple VAO's?

I'm a newbie to OpenGL and I was following a series by "thebennybox" on Youtube. Specifically his series on modern opengl programming. I thought I would try to implement his Mesh wrapper using the ...
7
votes
1answer
123 views

Parametrize set of unordered points in 3d space

Let's assume that we have some set of points in 3d space sampled from some arbitrary surface, without self intersections and mostly flat. Is it possible to get any parametrization over this set of ...
3
votes
1answer
688 views

How to blend World Space Normals

I am trying to blend two world space normals inside a shader. One comes from a tangent space normal map converted into world space using a classic TBN matrix and the other one is a mesh normal map in ...
3
votes
2answers
675 views

How to generate binary gltf array buffers?

I'm looking for any way which enables me to quickly generate gltf files including the conversion of plain array buffers (vertex, index, color, etc.) into binary (bgltf, glb, bin) files. I'm asking ...
3
votes
2answers
679 views

Is it possible to store the plain buffer data in gltf files?

The GL Transmission Format comes along with a JSON styled main file which basicly describes the scene and binary files which contain the buffers. I'm currently writing a WebGL library and I need to ...
5
votes
1answer
138 views

Image based lighting, tangent space coordinates, and optimization

When I saw an implementation of normal mapping that computed the TBN matrix in the vertex shader and converted everything (in particular the view vector and light vector) to tangent space at that ...
1
vote
2answers
461 views

Change particular color in an image

Suppose i have a image and I want to convert the portion of image that is red to blue(or any other color). One way to do this is extract red part of image using HSV or other color values and convert ...
4
votes
1answer
28 views

Why does the G1 term have a 2 in the numerator in Walter's formula, but not in Heitz's generalized formula?

In Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs, Eric Heitz derives the Separable Masking and Shadowing function as (P.83-84): In the mentioned Microfacet Models for ...
7
votes
2answers
220 views

What methods/technologies to reduce required performance for virtual reality are there?

I'm interested in virtual reality, but according to some sources, less than 1% of computers in use today have the necessary performance to run modern VR games, granted many of them are not intended ...
3
votes
1answer
440 views

Ray-tracing the Cornell Box results in really inconsistent image

So I have a vector of glm::vec3 containing the triangles for the classic Cornell Box called triangles. The Draw method casts a ray for each pixel on the screen and ...
4
votes
1answer
573 views

How to compensate low amount of rays reaching the light in a Path Tracer

I am trying to implement for research purposes a path tracer, but so far but results are not so good and I will explain you why. The general idea before getting to the code: I am working on paths ...
1
vote
1answer
260 views

Collision detection methods for 2D and 3D environments [closed]

I found many sites, books and articles, all about especifics algorithms, I listed some of them (like bounding boxes, bounding spheres, octrees and KD-tree), but any of these founds lists every ...
20
votes
3answers
5k views

Is Russian Roulette really the answer?

I have seen that in some implementations of Path Tracing, an approach called Russian Roulette is used to cull some of the paths and share their contribution among the other paths. I understand that ...
1
vote
2answers
4k views

How to load a model in .json in three.js

I need to load a model "somemodel.json" into my "movie.js".Can someone tell me where i am going wrong.I followed the steps given here. index.html ...
4
votes
1answer
989 views

How could I use bent normal map

This might be a general question but I have some difficulties about understanding baked bent normal maps and how to use it inside a shader in Unity. From what I understand, bent normals are ...
4
votes
2answers
494 views

Could we dispense the near clipping plane?

Would it be, at least theoretically, possible to render without a near clipping plane? Could raytracing ignore this perchance? Quite many budding 3d artists have a WTF moment the first time they ...
4
votes
1answer
114 views

inside and outside region identification from 2D contour

A 3D model is sliced against a plane and the resulting 2D contour is projected onto the plane. I am looking for an efficient algorithm to identify the inside and outside region of the contour. ...
5
votes
1answer
191 views

Unlit objects in deferred rendering

What is the best way to draw unlit objects with deferred? Like skybox, particles or just glowing objects? I thought about mask in alpha channel, check it in light pass and just set diffuse color but ...
10
votes
2answers
5k views

What is an index buffer and how is it related to vertex buffers?

I have a vertex buffer like this: 0.0, 0.0, 1.0, 0.0, 0.0, 0.6, 1.0, 0.6, 0.5, 1.0 I have the following index buffer: ...
1
vote
0answers
43 views

Trouble using java connectivity and data transmition on libgdx [closed]

Hello everybody i have a trouble making datatransmition with mine program just to give the idea im trying to move this blocks when i move mine cars Here I leave the encoding of mine server/client ...
4
votes
1answer
1k views

Computing camera front direction from Euler angles

I am new to OpenGL and Computer Graphics in general. Lately I was learning how to model a camera, specifically how to model the rotation of camera. I was introduced to Euler angles for this purpose. ...
4
votes
2answers
749 views

How to generate OSX Flurry screensaver

I want to generate video similar to OSX Flurry screensaver (screenshot, video), but I have no idea how it is made. Does anyone here has an idea about how it's made, its algorithm and method?
16
votes
2answers
5k views

How to properly combine the diffuse and specular terms?

As far as I understand, in a BRDF the Fresnel term is telling us the probability for a photon to be reflected or refracted when it hits a surface. The reflected photons will contribute to the ...
5
votes
1answer
200 views

Sine-based Tiled Procedural Bump

I am trying to implement this formula to generate bump but I am facing some issue. The result doesn't look the same it's much darker. Here is my result (without same parameters) but it is much darker ...
4
votes
2answers
543 views

Path tracer not rendering shadows

I am trying to implement for research purposes a gradient-domain path tracer. In order to achieve this step I first need a working Path tracer. I have been creating one so far but results are wrong ...
1
vote
1answer
558 views

Can Frameless rendering reduce latency? And, can FPGA do 3D rendering instead of GPU?

In virtual reality, the motion-to-photon time is very important. Oculus says it has to be less than 20ms. Maybe 10~15ms is better. Some people try to introduce Frameless rendering technology into VR. ...
1
vote
4answers
1k views

Cloud based VR would be the future?

According to the following assumptions, I think Cloud based VR would be the future: 1) Real world scene rendering needs ray tracing or other complex computing graphics technologies. It needs a lot of ...
1
vote
1answer
148 views

Can V-Sync avoid tearing? I think it can't. Am I wrong?

1) Update the front buffer will cause screen tearing, every one knows it. 2) But V-Sync, I think it still get the same issue. Why I get this idea? 2.1) When GPU flips to the back buffer, current ...
4
votes
1answer
93 views

Why does the integral of NDF over a solid angle equals the area where micronormals belong to that angle?

In Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs, Section 2.2, Mr Eric Heitz defines the distribution of normals as: And then, he goes on with the following assertion: I ...
7
votes
1answer
728 views

How are we supposed to fix brightness with square roots?

I recently watched this video that talked from a physics perspective how most of the ways we deal with color on the computer is incorrect because brightness is on a logarithmic not linear scale. ...
2
votes
0answers
92 views

Converting from 360 degree vr to rectangular

What I am interested in doing is taking a 360 degree stereo video (Oculus Rift etc), and a description of how the viewing direction changes with time (rather than reading from gyroscopes) and then ...

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