Questions tagged [rendering]
Questions about the conversion of a 2D or 3D model to a photorealistic or non-photorealistic image.
383
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What's the difference between PBR (pointed based rendering) and GS (Gaussian Splatting)
Over 20 years ago, there was a wave of "Point-Based Rendering" (PBR) or even "Point-Based Graphics". It started with two interesting papers, both published on SIGGRAPH 2000, "...
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Difference between inverse rendering and inverse graphics
I'm trying to learn computer graphics on my own and wanted to clarify -
What is the difference between inverse graphics and inverse rendering?
Would it be correct to say that inverse rendering is a ...
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1
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1
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When to apply backface culling, depending on the ray and material type?
I am currently implementing a ray tracer, which supports reflection and refraction.
I have the following types of rays:
camera rays
shadow rays
reflection rays
refraction rays
I have the following ...
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0
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gl_instanceindex takes location of my vertex input(so, it invalidate smy input for vertex)
Have problem with instanced drawing. gl_instanceindex takes input location of one of my vertex attributes. Why is it happening?
shader inputs:
...
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1
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34
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Vulkan+glm orthographic projection clipping unexpectedly
I am following along https://vulkan-tutorial.com/ and just finished the chapter on Uniform Buffers. I tried to change the projection matrix to see the outcome, however, when I change the zFar value in ...
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What is the fastest way to rasterize a triangle?
I'm making a triangle rasterizer for my 3d engine because I forgot to make a depth buffer and I was wondering what is the fastest way to rasterize a triangle,
I was thinking bresenham combined with ...
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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 ...
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106
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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 ...
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1
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1
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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, ...
0
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0
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36
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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 ...
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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,\...
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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 ...
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1
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148
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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73
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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{...
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1
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40
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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 ...
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1
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106
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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 ...
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3
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301
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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 ...
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133
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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 ...
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1
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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 ...
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0
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211
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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 ...
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1
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124
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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 ...
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1
answer
920
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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&...
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1
answer
49
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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, ...
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1
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82
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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:
...
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1
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101
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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 ...
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2
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297
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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 ...
user19809
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73
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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 ...
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40
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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 ...
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64
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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 ...
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0
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47
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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 ...
0
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1
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76
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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?
user19644
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1
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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 ...
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2
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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, ...
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1
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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 ...
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1
answer
291
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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 ...
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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, ...
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27
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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 ...
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1
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359
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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 ...
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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.
...
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72
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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 ...
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1
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118
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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 ...
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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 ...
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79
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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 ...
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112
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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 ...
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1
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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 ...
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