Questions tagged [rendering]

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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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15 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 ...
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1answer
47 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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58 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 ...
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1answer
51 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 +,*,/,...
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1answer
128 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
112 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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89 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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31 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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63 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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45 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
91 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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35 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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61 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 ...
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1answer
66 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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62 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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33 views

Probability of choosing the current strategy in the pbrt implementation of Multiplexed Metropolis Light Transport

In the description of the Multiplexed Metropolis Light Transport implementation of pbrt it is claimed that "the inverse probability of choosing the current strategy $(s,t)$ [...] is equal to <...
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1answer
48 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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38 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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50 views

Which is more important : Texel or Pixel rate? [closed]

I would like to know which is the most important ? More particularly in games or for the display of a desk (ex KDE Plasma, Windows 10 ...) ?
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0answers
24 views

Mitsuba builds targets with scons but throws “undefined symbol” error when trying to render scene

I am trying to implement a custom add-on for Mitsuba, but when I use the Heightfield I have defined in another function call(WaveBrdfAccel) in main.cpp it compiles without any problems but when I try ...
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1answer
100 views

light probe (for global illumination) placement techniques?

I'm learning light probes used for dynamic global illumination. I have a question regarding the placement of light probes, as based on most of the pictures I have seen, they seem to be placed ...
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31 views

Software Rendering Display Latency

I've been doing some reading as to how to reduce input delay on modern computing devices. A lot of my understanding from this comes from the VR research paper by Carmack explaining the numerous ...
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2answers
118 views

Why do identical polygons not z-fight in OpenGL?

Typically when coplanar or nearly coplanar polygons are rendered in OpenGL, the textures of each polygon mix together in a non-deterministic way. My understanding is that this is caused by the limited ...
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1answer
123 views

Tone Mapping in a physically based rendering ray tracer

I'm implementing a pbr ray tracer. Let's say that I'm at the end of the process: for each pixel pi, I accumulated the radiance value in vector pi = (radR, radG, radB). At this point, these values are ...
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1answer
83 views

how to update my scene graph?

I am updating my scene graph in response to user input and the network. What is the best way to do this? The updating threads are separate. Some approaches I am thinking about: double buffer. There ...
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67 views

Programmatic rendering of 3D animations

Many years ago I used POV-Ray to render some 3D animations. I liked POV-Ray's Scene Description Language (SDL) as I could generate the required files programmatically using other languages (e.g. Perl)...
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56 views

Optimisation of Geometry Pass

I'm trying to optimize a geometry pass for a game using dx11 and deferred rendering. (All test are performed on Nvidia GTX 1060 at fixed clock rate) After profiling with NSight it seems to have very ...
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1answer
69 views

How does Next Event Estimation work with transformed lights?

I am relatively new to path tracing, and I am trying to implement next event estimation. I am following the Monte Carlo integral used to compute the direct illumination from an area light: $$\frac{1}{...
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1answer
87 views

how many watts are in the SPD of the color white?

Please help. I'm trying to implement a ray tracer, going by the PBRT book and got stuck on an issue that I fail to find the answer to. My scenes are made from objects and light sources. From that, I ...
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1answer
103 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, ...
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1answer
66 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 ...
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1answer
55 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?
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0answers
89 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 ...
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2answers
125 views

What is a list of common, cheap, real time rendering algorithms?

I am well aware of the existence of Blinn-Phong shading, which is a great tool when you are doing, for example, modelling algorithms and wan't to focus on the model. In this case a full BRDF result, ...
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0answers
110 views

How to use Photometric Units with Rendering Equation?

So I was just reading up on how to create more Physically Based Lights and wandered into the realm of photometry. I read the paper "Moving FrostBite to PBR" and in it the author claims he decided to ...
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1answer
29 views

Can you generate your own HDRI maps without using photos?

For example, preparing a scene in Maya using standard lights and rendering out a panorama? Could they also be made from scratch in photoshop using 32bit color? Is there a reason why people don’t ...
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1answer
687 views

Anisotropic GGX BRDF implementation. How is it related to isotropic GGX BRDF?

Introduction I am implementing anisotropic GGX BRDF and have encountered strange behaviour of my implementation. I thought that if I compare the microfacet distribution function I have with the one ...
3
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1answer
126 views

Adding noise to gradient

I found this picture When you zoom in to any part of the image, the background looks a bit noisy/grainy. See pixels around "violent violet" label: I'm trying to understand how to achieve the same ...
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2answers
872 views

Multiple Importance Sampling in Path tracer produces Dark Images

So I recently implemented Multiple Importance Sampling in my path tracer which was based on next event estimation. The problem is without MIS I get images like, This is obtained by setting ...
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1answer
219 views

Texturing an “infinite” plane

I am rendering an infinite plane as described in the following answers: https://stackoverflow.com/questions/12965161/rendering-infinitely-large-plane https://stackoverflow.com/questions/7380250/how-...
2
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1answer
122 views

Rendering Equation for photons carrying flux

I am trying to understand the mathematical/physical foundations of photon mapping better. In the forward photon tracing step it is established, that the rays are carrying portions of total power (...
3
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1answer
228 views

Rendering Fluid Simulations?

I've read about Lagrangian and Eulerian fluid simulations and here's what I take from their methods: Lagrangian - Simulating fluid particles by calculating displacement for each particle Eulerian - ...
2
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1answer
116 views

Computing perspective directly

Assume the screen is axis aligned with origin at 0 and there is absolutely no view transformation. in other words we will simply try to project the model onto the screen plane following perspective. ...
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0answers
226 views

Understanding bad shadows with voxel ray tracing

I have a voxel raytracer that is generating some weird shadows and I want to understand what is the source of the problem. The image is voxelized, resulting in: I then generate Hard shadows from the ...
4
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1answer
153 views

How to apply wire texture for realistic rendering of embroidery?

I am building an algorithm which takes a bitmap image as input and render the image as an embroidery design. The different steps are : Vectorize the image, I keep only 5 colors (Done) Generate ...
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4answers
2k views

For shader math, why should linear RGB keep the gamut of sRGB?

sRGB is often contrasted with "linear RGB." Images are stored on disk and passed to displays in sRGB, which is approximately perceptually uniform in intensity. Shader math is done in linear RGB, ...
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33 views

How to apply SSRT to an existing image with associated depth map?

I have the following image and depth map from a CV paper: I want to know if there is an existing way to apply screen space rendering to a pre-existing image. Before someone yells ate me saying "Why ...
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2answers
229 views

Is it possible to emulate Vulkan on a non Vulkan compatible gpu?

I don't think there is much to explain here, since the question is pretty much in the title, but i'll try to explain myself better: My current laptop's gpu does not support Vulkan, so i was wondering ...