Questions tagged [rendering]

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31 views

Why does my image has a square pattern in cuda path tracer?

I am writting a path tracer in cuda following the Shirley's book. I am having a square pattern as an output. The size of the block change if I change the block dimensions. For this image, the block ...
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33 views

What is the simplest way to create basic 3d/isometric style images programatically like autocad/blender

I need the simplest route to programatically, via command line, through python or node, to create something like this using basic input of distance and 90 degree turn etc: https://i.imgur.com/SdY02gQ....
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1answer
41 views

Reference for Inverse Rendering

I'm not sure this is the right place to ask for this reference but it's worth the shot since it is graphics related. I'm looking for the very first paper describing what "Inverse Rendering" -...
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1answer
28 views

What is 2D BRDF Slice/Lobe?

I was recently trying to read some rendering papers and textbooks. The word 2D BRDF slice/lobe is often used while no official definition is provided. I know that BRDF is a 4D function of input ...
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1answer
47 views

How can I make a graphics demo without a frame buffer?

I am programming a microcontroller - a tiny 8 bit computer that has about 100Mhz - 300Mhz CPU clock speed and 64K application RAM (actually ROM), but only a tiny amount of RAM (6K) - nowhere near ...
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1answer
82 views

What are the use cases for multiple render passes?

From what I understand of Vulkan, we have a render pass with its associated image resources and subpasses, and each subpass accesses those resources and may synchronise with previous subpasses to ...
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1answer
35 views

Albedo image map to color's Light Reflectance Value (LRV)

In many datasets in the literature of both Computer Vision and Computer Graphics there is the albedo map of a scene represented as RGB images, which in principle corresponds to the diffuse reflecting ...
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0answers
51 views

Conditionals and branching in shaders

This is a quite wide subject which implies a lot of topics such as the platform or the compiler, but I think that it could be useful for everyone to know more about this. A common mistake is to think ...
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0answers
45 views

What's a good research topic in Computer Graphics?

I am currently trying to find topics for my master's thesis. I would really like to do something in the field of computer graphics, but I've been having trouble finding what are some current problems ...
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1answer
37 views

UV partial derivatives of a cylinder shape primitive

I am new to rendering and I would like to calcualte UV partial derivatives of a cylinder shape, which is parameterized by radius $R$ and length $L$. Using cylindrical coordinate mapping, for a surface ...
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0answers
78 views

Why does my self-written rendering engine make further away objects look larger?

I am writing a very simple rendering engine. I have already made a few tests, but somehow the images it creates look wrong. Objects that are further away from the camera look larger than objects ...
2
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1answer
57 views

Rendering moist/wet materials like human anatomies for surgical simulators

Real human anatomies look wet/ moist when operated. I am looking for some good methods for rendering anatomies in a virtual simulation, and hence I have done a literature survey on 'Rendering wet ...
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1answer
66 views

How to display an in-memory framebuffer

I'm planning to write a small software rendering engine (before anyone asks, it's kind of a learning/scientific experiment for me). Before writing any code, I'm already stuck at the very first step: ...
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0answers
46 views

Accelerating dose calculation for a radiation therapy planning system

During radiation therapy, appropriate radiation is fired from various positions around the patient. Radiation therapy planning determines the values of the radiation at various positions. This ...
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1answer
41 views

How are digital painting canvas rendered?

Digital painting and raster graphics software like Krita and Photoshop have a canvas where you can paint with brushes. From a programming perspective, how is this canvas rendered? Can it be included ...
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1answer
79 views

Has anyone found an analytic solution to the product of spherical gaussians from Xu et al?

In section 4.2 of this paper: http://cseweb.ucsd.edu/~ravir/274/15/papers/a209-xu.pdf Xu et al approximate the product of 2 anisotropic Gaussian distributions. I want to know if someone has found not ...
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1answer
47 views

Converting Vertex and Index buffers to a File Format

I have many sets of vertex and index buffers that I’d like to render on to the screen. Ideally each model in different locations with-in world space. I’m actually doing a statistical study on spatial ...
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1answer
46 views

Finite difference wave equation shown in paper is wrong?

I'm trying to produce wave surface animations, and I came across this paper: Fast_Water_Animation_Using_the_Wave_Equation_with_Damping. In the paper they go to provide the following equation: At ...
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0answers
41 views

2D metaballs with marching squares and linear interpolation

I struggle do understand how linear interpolation works in the marching square rendering algorithm context. I created simple example in GDScript (Godot) of random floating metaballs to demonstrate ...
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1answer
60 views

Ray Tracing Bounding Volume Hierarchies nodes

I'm new to computer graphics programming so I apologize in advance if my question is stupid. I'm trying to implement a BVH for my ray tracer and I looked at some lectures explaining BVH. They all ...
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1answer
51 views

In Game Engines, how much of the graphics pipeline is already written?

I'm trying to understand how much graphics programming actually needs to be done if you are using an engine like Unreal Engine to build and package a game. I understand some of this might have to do ...
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1answer
57 views

Two questions on Gamma correction and Tonemapping

I have few questions regarding tone-mapping and gamma correction. is a tone-mapping operator a function whose output is a value between [0,1] ? If this isn't the case and since gamma encoding ...
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0answers
39 views

How to read illum value from mtl file using Assimp library?

I am loading an OBJ file using the ASSIMP library. Following is the MTL file associated with the obj file. ...
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1answer
79 views

glBindImageTexture returning INVALID_VALUE

I am currently having an issue with OpenGL as I am trying to load some vector information into a 3D texture. Currently, I am developing in OpenGL 4.6 which should support Image bindings. this my ...
2
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1answer
37 views

Controlling “zoom” and “position” of a cubemap in shaders

I am trying to mimic reflections in image composition using shaders. I have gotten this far: In this image the floor is "reflecting" the back wall, however the reflection is uncanny because the ...
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0answers
82 views

How to achieve higher FPS for my GPU pathtracer?

So I've written a GPU based pathtracer using OpenCL-GL interoperability. The system uses the Mega-Kernel Approach instead of a wavefront one as I was aiming it as an educational software for other ...
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1answer
56 views

constant pixel width for any scale

I have a standard 3d camera/projection/model setup that renders rectangles with a WebGL shader. Users can zoom out and fly anywhere. I want to make sure that regardless of the scale, width of the ...
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1answer
77 views

BDPT - How to handle deterministic ray PDF?

I'm trying to implement a simple BDPT without MIS as described in Lafortune's paper. I've used the weighting scheme defined in the paper in which they suggest that the weight be based on the surface ...
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0answers
90 views

Procedural Generation of 4D Shapes

I'm curious if anyone has any insight into how one might procedurally generate 4D objects, as showcased in Miegakure (or the developer's other game, 4D Toys ). I built a program a while back to do ...
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1answer
61 views

Extracting information from EXR Files

I am relatively new to computer vision and image processing. I have a single EXR file with 7 channels: 1-3 give me the RGB values, 4-6 give me the surface normals coded as RGB values and 7th channel ...
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1answer
152 views

Which technique should be used for rendering under water images, Ray tracing or Radiosity?

Rendering is the process of computing a three-dimensional geometric description of a scene into a two-dimensional image representation that looks real. Ray-tracing and Radiosity are two of the most ...
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35 views

Inverse path sampling in (bidirectional) path tracing

In Section 4.1 of the paper Fusing State Spaces for Markov Chain Monte Carlo Rendering, it is described that the CDF $P$ of the distribution of paths of length $k\in\mathbb N$ may be factored into a ...
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0answers
24 views

Computing inverses in Reversible-Jump Metropolis Light Transport

Say we are sampling a path $\rm x=(\rm x_0,\ldots,\rm x_{n-1})$ of length $n-1$ using bidirectional path tracing. Let $p_s$ denote the area product density corresponding to the used connection ...
3
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1answer
67 views

Intrepret path/light tracing by rewriting light transport equation

Given the rendering equation: $$ L_o(x, \theta_o) = L_e(x, \theta_o) + \int_{\Omega} \! f(x,\theta_i,\theta_o) L_i(x,\theta_i) \cos(\theta_i, \theta_o) \, \mathrm{d} \theta_i. $$ Rewriting it using ...
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0answers
87 views

BSP tree rendering

As a little project, I'd like to implement a BSP merging algorithm for Boolean operations on solids. But to even tell whether it works, I need some way to render the BSP tree. In other words, I have a ...
3
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1answer
134 views

Is there a way to perform calculations of Mandelbrot set using only integer numbers?

I would like to create program in JavaScript (JS) which draws Mandelbrot set with arbitrary precision (zoom). In JS there is build in integer type BigInt which support simple operations like +,*,/,...
2
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1answer
172 views

Rendering equation for spherical lights

I am currently implementing spherical lights in my DirectX game engine. I decided to build the shading formula from the classical rendering equation. Here is what I get: The simplifications show that ...
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4answers
279 views

Why isn't rasterization combined with raytracing more often?

If I'm not mistaken, you can make a hybrid renderer which lets a rasterizer solve the visibility problem, then shade all of the projected shapes with a raytracing algorithm. It seems that this isn't ...
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0answers
102 views

Irradiance field approximation with black probes

I'm posting here after some time searching the Internet and reading presentations and papers, to find out the best options to solve the problem I have. I'm implementing irradiance field with ...
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0answers
36 views

Factorize probability densities in Bidirectional Path Tracing

Say we have fixed a length $k$ for paths we want to sample using bidirectional path tracing as described in the Physically Based Rendering book. Let $q_{s,\:t}$ denote the probability density of ...
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0answers
100 views

Why does the reflected component in Lambertian path tracing get multiplied by a factor of 2?

I would like to intuitively understand the Path Tracing equation/formula/pseudocode, but I'm not fully getting the last return statement. As per Wikipedia page: <...
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0answers
63 views

Voxel terrain generation optimization

Chunking is used as optimization in voxel terrain generation to not render hidden part of the terrain by dividing the terrain into chunk and make it a single mesh. Instanced rendering is used in ...
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1answer
213 views

Difference betwen Rendering Equation, Lighting model, Ray Tracing, Global Illumination and Shadows?

What is the difference between all these techniques? I know what a lightning model does, eg Phong, Flat, Gouraud. As far as I know both Ray Tracing and Global Illumination are just lighting models ...
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0answers
57 views

How to render multiple shaders per mesh

I've tried looking everywhere, but I just don't get it. How is multiple shaders assigned to a mesh if you can only bind a single shader in OpenGL? Assume I have a mesh with a texture shader and now I ...
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0answers
106 views

Implementing GGX VNDF importance sampling with DXR

I am currently implementing the GGX specular BRDF in a DXR raytracer using the importance sampling method describe by Heitz I am sampling the VNDF with: ...
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0answers
25 views

Report standard deviation in Rendering results

I noticed that a common metrics for image quality assessment (Monte Carlo path tracing) is MSE between the generated image and a reference one. My question is: why isn't the standard deviation ever ...
2
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1answer
68 views

Mixing HSV Channel

I have a question about the saturation channel. 1.) So far I know, that saturation channel only give intensity to Hue channel, but I do not understand, how saturation channel can be dark and what is ...
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0answers
81 views

Multiple Importance Sampling in Bidirectional Path Tracing

I'm trying to understand the computation of the path density described in the book Physically Based Rendering. They assume that a path $$x=(x_0,\ldots,x_{n-1})=(q_0,\ldots,q_{s-1},p_{t-1},\ldots,p_0)$$...
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1answer
64 views

Estimating the position of vertexes in a 3D model

Introduction to my project: We are machine learning scientists and working on a biomedical system for tracking tongue for speech pathology using a technology called EMA (Electromagnetic ...
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0answers
65 views

How to display image from CUDA / What API to port my project to for real-time raytracing?

I started a raytracing project using the python numba library which provides a just-in-time compiler for CUDA kernels. When the scene is rendered my result is a 1920 x 1080 x 3 RGB array in GPU memory....

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