Questions tagged [rendering]

Questions about the conversion of a 2D or 3D model to a photorealistic or non-photorealistic image.

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How to create a more photorealistic ocean?

Photorealism has many elements. Take, for instance, the figure 1 below, a shot from Dune Part One movie. Figure 1 The process of production of a image such as this one, is laborious and involve more ...
M.N.Raia's user avatar
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Multiple importance sampling with Next Event Estimation gathers less energy compared to One-sample-model

I'm developing a webgpu pathtracer using multiple importance sampling with two similiar techniques, next event estimation and one-sample model. For some reason, next event estimation seems to gather ...
Domenico's user avatar
1 vote
1 answer
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Why is the indirect illumination (using IBL) in my PBR shader overpowering everything?

I'm trying to implement a basic form of physically based rendering (PBR) and I am using the PBR tutorial from learnopengl dot com as a reference. The PBR I am implementing consists of two parts, ...
unusually_crispy_crisps's user avatar
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Which thread should own, acquire and present a window surface?

I’m writing a multithreaded renderer. It happens to use wgpu in Rust, but that probably has no bearing on my question except perhaps it will influence my terminology. Currently, I have two threads, a ...
junglie85's user avatar
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How does a path tracer capture light falloff if it deals exclusively with radiance?

My understanding is that path tracers deal with radiance because radiance is constant along a ray. You simply go through and evaluate the light transport equation: $$ L_o(p, \omega_o) = L_e(p,\...
Chris Gnam's user avatar
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Problems with distributed ray tracing and particle system

based on the ray tracing stunning effect, I'm considering a resilient distributed ray tracing implementation, I've just finished a basic computer graphics course, and I'm currently working on directX ...
Haitao Xiao's user avatar
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1 answer
101 views

Lambertian surface and the luminous intensity

I am currently studying the basics of photometry to better understand the rendering equation of Kajiya. One thing I'm currently struggling with is Lambert's cosine law. Let's go over the premises: A ...
Bartolini's user avatar
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Ray Tracing in Camera-World Space

I am trying to implement rendering in "Camera-World" space following PBRT-V4's camera implementation in my Rust ray tracer. I Have been trying to solve that for days I read these multiple ...
AregevDev's user avatar
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215 views

Spherical Harmonics for view-dependent effects in research of learned radiance fields (NeRF, 3D Gaussian Splatting)

In research on making the rendering of learned radiance fields (e.g., neural radiance fields) faster, many approaches use Spherical Harmonics (SH) to approximate view-dependent color (e.g. baking SH ...
wawaderwaran's user avatar
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What kind of code would it take to visualize just 1 3d gaussian in Godot?

I'm trying to create the simplest possible implementation of the gaussian visualization code from this paper in Godot, https://repo-sam.inria.fr/fungraph/3d-gaussian-splatting/ but I just don't even ...
Ethan's user avatar
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How to correctly handle rendering of ~600000, arbitrary colored 2D squares with WebGL?

Information I have to render a map, that is rendered as a 2d collection of squares of different color, separated by white lines horizontally and vertically. There may be ~600000 squares surrounded by ...
h4ckthepl4net's user avatar
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Partial Derivatives of Spherical Angles and Refracted Ray w.r.t Surface u,v

I am reading on "Specular Manifold Sampling" paper with the implementaion(for the simple case) here on Mitsuba at github. As part of the calculation it needs to compute partial derivatives ...
ali's user avatar
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1 answer
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Confusion regarding incident direction in render equation

I am studying from pbrt-v3 and the rendering equation has just been introduced as $$ \underbrace{L_\mathrm{o}(\mathrm{p},\omega_\mathrm{o})}_\text{Outgoing radiance }=\underbrace{L_\mathrm{e}(\mathrm{...
Scene's user avatar
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Sampling scattering direction around directions other than the last ray direction

In a path tracer, if we want to sample a ray direction in scattering medium, we can use phase function sampling, which actually use the direction of the ray before sampling as a sort of anchor to ...
Enigmatisms's user avatar
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HTML Canvas not drawing

I'm working on a 3D Renderer with the canvas element and JS but currently the cube I made is not rendering. I currently have it set to just render a wireframe of the cube and am hoping to render the ...
GryphonFire7's user avatar
2 votes
1 answer
92 views

White spots when rendering diffuse material with environment light

I am trying to implement a simple shader. A round ball object is rendered with uniform albedo and I noticed some strange white spots on the outputs. I perform importance sampling with 512 light ...
Ivan's user avatar
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How does higher draw distance strain the CPU?

I am looking at many games like Dead Island 2, Red Dead Redemption 2, and Minecraft and I see that while the render distance grows, the CPU load grows with it. Why could this be happening? Lack of ...
Vasilescu Andrei's user avatar
1 vote
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Is it possible to render to a octahedron texture directly?

I am considering using octahedron textures for environment mapping, opposed to sphere or cube mapping due to their low memory footprint and the quality they result in. Is there a possibility to render ...
Raildex's user avatar
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1 answer
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Importance sampling in a path tracer

So, I'm attempting to implement a monte carlo path tracer that uses the ggx brdf model. However, I'm rather confused about how to sample the light direction. I know that theta and phi can be sampled ...
RandomPigYT's user avatar
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127 views

One-sample model Multiple Importance Sampling with balance heuristic

Recently I feel a bit confused about one-sample model MIS. One sample model MIS can be found here in Veach 1997. 9.2.4 The one-sample model, and this one-sample model is widely used in the opensource ...
Enigmatisms's user avatar
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1 answer
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Triangle Rasterization Shaking Issues

I am making a Software renderer, and I noticed that there is a screen shaking like effect happening. shown in the first video: I tried doing filling without clipping against the small square, and the ...
Serilena's user avatar
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When do we need Dx12 Descriptors to be contiguous?

In many tutorials and examples code of DirectX 12 we can find ways to manage descriptors by creating a few descriptor heaps and allocating manually descriptors inside of them (e.g. in Mini Engine the <...
trfd's user avatar
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1 answer
562 views

What does GGX stand for?

Many render engines implement the microfacet model for rendering surfaces that are rough, metallic, and/or transparent, a concept first published in "A Reflectance Model for Computer Graphics&...
NullPointerException's user avatar
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How to design an ergonomic software rendering pipeline with painter's algorithm?

I wrote my software renderer with C++20 and the DirectX Math library. The pipeline so far consists of these steps: I use vertex buffers (...
rmvd's user avatar
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What algorithm approximates a "hand sketched" look for rendering diagrams?

I see a number of applications where polygons, lines, splines, etc., are algorithmically given a "hand drawn" look. What algorithm or general approach is applicable for this? As an example, ...
Mark Harrison's user avatar
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1 answer
61 views

My projection matrix for OpenGL fails on non-symmetric boundaries

Assuming my viewing volume has x coordinates varies from l to r, and y varies from top to bottom, and finally z-axis varies n to f, I derived the following projection matrix: ...
Serilena's user avatar
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1 answer
97 views

With a light source at (0,2,0) and unit cube (from [-1,1]) using a given shading formula, how is the r,g,b for each surface calculated?

The above problem is from a past Computer Graphics exam. I am particularly confused about the explanation given, firstly for the top and bottom planes (since the direction of normal for top plane ...
LC796's user avatar
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2 answers
217 views

Whats the best way to render (2D) parametric curves with uniform stroke width?

I want to create a rendering engine that mostly renders parametric curves on a 2d screen. As far as it seems, todays graphics are all dependent on vertices and matrices, so not sure where to start or ...
user avatar
1 vote
0 answers
67 views

How does changes in vertex data work?

I have been learning computer graphics and for some time and can't seem to wrap my head around one concept. How to handle vertex data changes? Ex. 1. I have a text rendering on a screen. And up on ...
amberbrew's user avatar
2 votes
0 answers
38 views

Optimized 3D rendering using dots and/or line segments of different sizes in Scratch

I'm developing a 3D rendering engine in Scratch, which is a block-based visual programming language. It does not have any support for bitmap rendering, but there is a "pen" plugin that lets ...
Peter Marshall's user avatar
5 votes
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59 views

Facetted look when using SampleBias

I am writing a simple material system for a game. Each material can have a specular value (phong) that is translated into "smoothness" via environment map. Similar to PBR, I compute a ...
Raildex's user avatar
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1 vote
0 answers
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How to display real time 3-D orthogonal vector rotations?

I'm an embedded developer here with very little experience in computer graphics. I'm currently working on a GUI that can display a calculated inertial solution at run time. I have hardware that can ...
Henry Gilbert's user avatar
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1 answer
66 views

Does OpenGL allocate on glBegin/glEnd?

You can enclose arbitrary amount of vertices within glBegin/glEnd statements. Does OpenGL limit the number of vertices you create or it allocates memory for more?
user avatar
1 vote
1 answer
131 views

Can anyone summarize in simple terms, how PSSMLT/MLT algorithms work?

I understand backwards path tracing and bidirectional path tracing (BDPT). However I'm failing to understand how Metrpolis Light Transport methods are even remotely feasible to run. My understanding ...
Chris Gnam's user avatar
4 votes
2 answers
1k views

What is the difference between a "meshlet" and just a small mesh?

Obviously, conceptually, a meshlet is just a small mesh. But what is the reason for making the distinction then? I'm assuming it has to do with how they are implemented. In a meshlet architecture, ...
Chris Gnam's user avatar
0 votes
1 answer
131 views

How can I transform the circular blinn-phong specular into a square shaped highlight?

I am creating a custom shading model in Unreal Engine and I would like to create a square shaped specular highlight, without changing the shape of the light itself. I tried following the approach ...
mbl's user avatar
  • 301
1 vote
1 answer
238 views

Path tracing: how to deal with ray hitting an emitter

I am writing my first path tracer and kind of feeling confused by some mechanisms. For example, when I trace a ray and the ray hits a area emitter, then how to determine the radiance of this direct ...
Enigmatisms's user avatar
4 votes
2 answers
250 views

cosine term in rendering equation

Rendering equation's value can be estimated with Monte Carlo (Physically Based Rendering: Light Transport I: Surface Reflection): $\begin{equation} \begin{split} L_o(p, \omega_o) &= \int_{S^2}f(p, ...
Rahn's user avatar
  • 183
1 vote
0 answers
26 views

A fresh perspective confusion about a paragraph

I am trying to re-implement the paper "A fresh perspective" In this paper there is one paragraph on secion 2 that reads: Usually, $z_s = z$ is the depth value of the point $P$, unchanged by ...
Makogan's user avatar
  • 1,706
2 votes
1 answer
203 views

Rendering equation integration variable change

I'm watching the TU Wien rendering lectures in the course we were presented with a rendering equation (first one on the screenshot) and then another, which results from a change of variables (if I ...
analysis1's user avatar
1 vote
0 answers
208 views

Calculation of reflection vector in Phong specular lighting

I wrote the following phong reflection model for ray tracing in Rust, but I am not sure about the calculation of a reflection vector for the specular reflection. ...
user48423's user avatar
1 vote
0 answers
63 views

Inverting perspective projection doesn't yield frustum?

I have a cube with 8 vertices representing the $[-1,1]^3$ cube vulkan uses for device coordinates. The perspective projection matrix takes a frustum and maps it onto this cube. It thus makes sense ...
Makogan's user avatar
  • 1,706
0 votes
1 answer
103 views

OpenGL - How to increase view space coordinate range in X and Y axis

I'm trying to render some objects but apparently X and Y coordinates need to be really small in-order to get something on screen. See this example of 2 lines The world space coordinates for these ...
gallickgunner's user avatar
1 vote
0 answers
64 views

Question about reconstruction filter in ray tracing?

Suppose we have an 512x512 image, then the value of pixel j should be $I_j = \int_{0}^{512} \int_{0}^{512} h_j(u,v)L(u,v) \,dudv$, where $h_j(u,v)$ is the filter function for pixel j, $L(u,v)$ is the ...
Andy's user avatar
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1 vote
0 answers
71 views

Imprecise TEXCOORD interpolation of a screen quad in DirectX

I was debugging with RenderDoc an issue on an app based on Directx11 and 12 that draw screen space quads to perform various baking steps. These baking steps just render a quad in clip space without ...
Michele M.'s user avatar
1 vote
1 answer
103 views

3D to view plane projection

I am trying to draw points of a 3D sphere onto my monitor as if I was looking out into space. Me, the viewer, is at (0, 0, 0). The plane of my monitor is at (x, y, 1) and I have a sphere out in ...
Dan Wood's user avatar
2 votes
1 answer
206 views

How to draw smoother lines and triangles?

I am currently creating my own 3D renderer. Here is a coloured cube created by the renderer. I modelled cube using a set of coloured triangles. Notice extraneous lines from edges and they does not ...
Jimmy Yang's user avatar
1 vote
0 answers
42 views

How to visualize the outgoing directions sampled from BSDF?

I'm trying to find a way to visualize the outgoing directions sampled from BSDF. More specifically, for a given incident direction, I can sample the outgoing directions, using 'BSDF sample', and I ...
Wenjian Zhou's user avatar
0 votes
1 answer
169 views

Bump mapping WITH precomputed tangents?

Most bump mapping (meaning black and white height map) uses Tangents/Bitangents computed from Position using dFdx/y. And they also compute the offsets/derivatives of the height map using dFdx/y. The ...
Ascalon's user avatar
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2 votes
2 answers
252 views

Adding cos(θ) from rendering equation ruins the renderings

I'm following Ray Tracing The Rest of Your Life to implement a ray tracer, but the explains on math (mainly pdf part) got me confused so I followed Rendering Equation to understand the math behind. As ...
Rahn's user avatar
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