All Questions

Filter by
Sorted by
Tagged with
2
votes
1answer
54 views

GL_DEPTH_CLAMP has no effect (reverse z)

In an effort to improve cascaded shadow maps, I have looked into using GL_DEPTH_CLAMP and moving the near and far plane just around the actual view frustum instead of the global bounding box. But the ...
2
votes
0answers
101 views

HalfEdge data structure in openmesh, create_face function explanation

Does anyone have experience with open-mesh or computational geometry and can kindly explain what exactly happens in the function below? ...
1
vote
1answer
86 views

How can I transform an ellipse into a circle?

I have an ellipse which has -45 degree axis. How can I transform the ellipse into a circle? Can I use shear transformation along the x/y axis?
3
votes
1answer
91 views

3D coordinates of intersection point in clipping for a rasterizer

When doing clipping in homogeneous coordinates, we need to find the coordinates of the intersection of the viewing frustum with the line to be clipped. This can be done easily if we want those ...
4
votes
0answers
109 views

Learning light transport using Q-Learning

I am trying to reproduce the results obtained by Dahm et al. in the paper Learning Light Transport the Reinforced Way. This method takes advantage of the similarity between the Bellman equation (Q-...
0
votes
1answer
55 views

Rendering 3-D point clouds obtained from depth maps as a 2.5D video

Suppose I have code to generate a bunch of frames, each of which is a depth map(I have access to the matrices which represent depth) which in turn is used to generate a point cloud. One frame would ...
3
votes
1answer
140 views

Why the ray tracing result looks weird?

I followed the book Ray Tracing in One Weekend and implemented a simple ray tracing procedure. There are 100 random samples every pixel for antialiasing, but the render result looks weird: There is a ...
2
votes
1answer
103 views

Floating Point Operations in Line Drawing Algorithms

When it comes to line drawing, DDA is the simplest and most intuitive algorithm, the core idea being: compute the slope of the line for every increment in x, increment y by the slope However, DDA is ...
-1
votes
1answer
93 views

Unsolved Problems in CQ to this day?

What problems haven't been solved yet when it comes for instance in rendering,deferred rendering, Volumetric lighting, ambient occlusion or in any other interesting area. When i say unsolved problems, ...
2
votes
1answer
62 views

Why is cos(𝜃) in the denominator in the reflectance equation and in the numerator in the shading equation?

Background: I'm reading https://learnopengl.com/PBR to learn about PBR. In the theory slide (https://learnopengl.com/PBR/Theory), the author has the reflectant equation as The theta (the angle ...
3
votes
0answers
40 views

NURBS Weights De Boor's Algorithm

I am having trouble implementing an algorithm for 3rd degree NURBS. I have been able to program 2nd degree ones from the equations described here but I am not able to derive an equation for Rational B-...
4
votes
1answer
120 views

Do straight lines always remain straight when projected with a perspective camera?

If I have a straight line in 3D space and I use a camera matrix to do a perspective projection into a 2D plane/screen will the resulting line always be straight too? If I project the start point and ...
0
votes
1answer
88 views

Sphere Texture Mapping Algorithm

I am trying to generate UV coordinates automatically to map a texture on a sphere. The problem is with seams when going from 0.8 to 0.2 there is a discontinuity and interpolation in fragment shader ...
4
votes
1answer
98 views

Why is it easier to inverse transform every object in a scene than to transform a camera?

My lecturer for a computer graphics (raytracing) paper has stated that 'It is easier to apply the inverse transform to the world than it is to apply the transform to the camera.' The example given was ...
1
vote
1answer
58 views

How to implement physically based unit in pbr renderer

According to this note, Frostbite use photometry unit in their calculation. I am trying to mimic this feature, but I am not sure what transformation need to be done. I will try to explain what I have ...
-1
votes
1answer
82 views

Difficulty including GLM into Visual Studio with OpenGL

I have been trying to implement GLM (math library) into Visual Studio with OpenGL. I have followed and watched many online resources that point me to include only the GLM folder inside the ...
1
vote
2answers
329 views

Very efficient/fast marching cube implementation

I was wondering if there's any known technique/algorithm that would compute a mesh generated by the marching cubes but hierarchically (like a divide and conquer strategy), in the implementation I know ...
1
vote
1answer
28 views

Identify plane of symmetry in 3D mesh

Is there an efficient way to identify the plane of symmetry in a 3D mesh? Preferably with existing code / software but if anyone knows how to implement it that would also be helpful. Example of the ...
0
votes
0answers
20 views

Open source tools for extracting hi-res images from video

I found recently an article in which they describe a technique to extract high resolution images from a standard quality videos. The technique exploits the fact that in a typical video the camera ...
0
votes
1answer
62 views

How to draw depth-based volume in real-time

Normally when we talk about realistic transparent volumes, we care about refraction (and total internal reflection), and we care about scattering. But there's a much simpler case of volume ...
1
vote
1answer
56 views

Organic 2d tree generation

I'm looking for a code to generate organic 2d trees like thiskind of shapes Gerard Ferrandez has an example to generate some tree but not organic like the picture shape https://codepen.io/ge1doot/pen/...
1
vote
1answer
45 views

How to translate the center of an equirectangular projection?

I'm trying to perfectly align two or more equirectangular photos of the same place taken from slightly different positions. Using an example provided by openMVG I managed to get the relative position ...
0
votes
1answer
113 views

smallpt: ray scattering and Importance Sampling

Introduction For those familiar with smallpt by Kevin Beason: In path tracing, when rays hit a surface, they are scattered and the theta angle (the angle between the normal to the surface and the ...
0
votes
1answer
50 views

What are the parameters measure the performance of a rendering? [closed]

Let's say I designed a housing model and rendered it using a rendering engine. how can I measure the performance of my rendering?
1
vote
0answers
80 views

Should I expect differences with explicit light sampling other that the noise?

I am trying to understand why my explicit light sampling implemetation does not produce the same results as my naive path tracer. Here are my results : Naive Version : Explicit light sampling ...
1
vote
0answers
40 views

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 ...
1
vote
1answer
92 views

smallpt: when to stop diffuse ray scattering

For those familiar with smallpt, the ray tracer in 99 lines: I am checking the code, and there is something that is not clear to me in the DIFFUSE ray scattering. After the rays are shot, they keep ...
3
votes
2answers
148 views

Why does opengl use 4d matrices for everything?

What I managed to figure out is that the first 3*3 is used for rotation and scale and the 1*3 at the end is used for position, but what is the bottom row used for? is it only for clipping related ...
1
vote
0answers
25 views

Help with efficient quadtree vertices indexing to avoid redundancy

I am creating a quad tree from ground zero, because I am going to collapse it from bottom up I am refining it with a certain LoD level. I am using glm for mathematics and opengl for rendering. ...
0
votes
1answer
120 views

SSAO - artifacts appearing

I am trying to implement SSAO using DirectX11 but instead I got white screen with few black dots on model. My suspect is that kernel generation or usage might be wrong. I've tried changing order of ...
2
votes
1answer
96 views

Clarifying vulkan glsl std140

So I have a uniform block that looks something lile this { mat4; mat4[128]; uint[16] } The block should total up to 8320 bytes. After aligning by 256 bytes for nvidia, that brings the total ...
2
votes
1answer
84 views

2D Line of Sight + Visibility Calculations

I am currently working on an algorithm to calculate visibility in a 2D top-down level. The level contains actors, with position and "sight" information walls, ...
1
vote
0answers
53 views

How to hide a part of a geometry dynamically using a shader in three.js

I have a very big geometry in three.js and I want to hide a section of that geometry along an axis (for example every vertex with a Z>N must be hidden). My idea is to create a custom shader in GLSL ...
5
votes
0answers
134 views

Where do “fireflies” come from?

I'm using a renderer developed by other people, and I found there are fireflies. It is strange that in a completely diffuse scene, there are still fireflies presented. To my understanding, I think it ...
5
votes
0answers
159 views

How to account for self intersection with large ray tracing scenes?

I'm working on a hybrid real time ray tracing project and trying to tackle the problem of self-intersection with larger scenes due to loss of float accuracy. The logic I'm trying to use is based on ...
3
votes
1answer
87 views

Compute shader textures compared 2D float4 arrays

I am wondering is there a difference in performance between using floating point textures as my 2D float4 array vs just passing in 2D float4 arrays? 2D float arrays eliminate the need to do texture ...
0
votes
0answers
40 views

Weight space in libigl

I'm trying to use the function of libigl uniformly_sample_two_manifold, but it does not work as described and there is no documentation whatsoever to help me understand why. I have a 3D mesh ...
1
vote
0answers
40 views

Anti aliasing thin features in textures

Assume I have a texture with a repeating line pattern. The lines are exactly 2 texels wide (really thin). Ans very spaced out (50 texels in between each line). I am now struggling with the ...
0
votes
0answers
96 views

Lanczos filter implementation issue

I tried to follow Nathan Reed post Antialiasing: To Splat Or Not to implement splat method. The image I am getting thorugh the Lanczos filter is very different than Nathan. I do not understand where ...
1
vote
1answer
68 views

Some questions about working in 0-255 integers instead of single precision floating point colors

I have many objects that store their color values. At the moment I'm storing them as vec4 values, that is four 4-byte values for RGBA, mainly because this is how the shader reads them. I was thinking ...
1
vote
0answers
50 views

Questions about a compute shaders from some source code using threads

I am trying to learn compute shaders from source codes, but i am a bit confused by whats going on in the code so am hoping someone can help answer some questions i have. The algorithm is the fast ...
1
vote
1answer
53 views

Simple Two Point Perspective of a Cube

I know this question may be a little basic, but still I haven't found an answer for it anywhere. Let's say I have a normalized cube; vertices at (+-0.5, +-0.5, +-0.5) If I render it on screen (...
0
votes
1answer
137 views

Monte Carlo Importance Sampling

I am following the "Ray Tracing - the Rest of your Life" book by Peter Shirley and I am facing some troubles in the implementation of Monte Carlo importance sampling, and Direct light sampling. Monte ...
-1
votes
1answer
86 views

Where should I learn shaders as a vulkan user?

I have no prior experience with any other graphics low level libraries and I have barely any clue how shaders work, any book related to shadings is bloated with opengl code and is demoralizing.
1
vote
1answer
51 views

Is `groupshared` memory stored in L2 cache of GPU?

The article says that L1 cache is shared by work items in the same work group(aka. SM) and L2 cache is shared by different work groups. In Direct3D, it seems that a thread group (which is specified ...
0
votes
1answer
117 views

How to simulate a line laser diode?

I'm interested in simulating the way a laser line deforms when it strikes an object and runs along the surface of it. Which concepts would be involved? Is there any 3D modeling software out there that ...
1
vote
1answer
104 views

ShadowMap peter-panning and wrong direction

I am creating Forward-Rendering DX11 engine and I have some troubles with shadow-mapping algorithm as it doesn't work as supposed. As you can see - shadow is peter-panning and looks totally not ...
2
votes
0answers
88 views

How to model braids?

Many hair simulations render their hair as lines (usually splines). Since hair is a really thin object. if the hair is braided, rather than having thin infinitesimally small cylinders, you have ...
2
votes
0answers
67 views

Trying to optimize texture mapping

We are developing a PPI plot for a radar system, similar to the following: NOTE: 1 radial is defined as a single slice of data within the circle, and 1 range gate is defined as a single point along a ...
2
votes
0answers
33 views

Mantiuk's contrast mapping seems to amount to a gamma correction

I'm reading this paper and one thing sticks out at me. Let's say I use the approximate transducer: R = 54.09288 ·G^0.41850 Then I scale it: ...

15 30 50 per page