# All Questions

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### BC7 texture with alpha has the same size as BC7 without alpha

So i've a made a texture. I've saved the RGB one with BC7 compression, then added alpha channel[specular map] with varying levels of grayscale, and saved the file again as RGBA with BC7 compression. ...
74 views

### Why does the camera not remain child of the other camera after adding it in osg?

I am writing an OpenSceneGraph based program that uses two cameras, one to render the preview for the user and one that uses a callback to make screenshots with MRT. The exporter camera is using an ...
18 views

### What modern C++ Unit Testing Framework do you use for highly parallel image, 3D and higher dimensional matrix processing workloads?

Most of the existing open-source libraries such as OpenCV, Tensorflow, and Pytorch use Google Test. I would like to know about strong alternative testing frameworks that thrive under a similar ...
90 views

I am relatively new to compute shaders and gpgpu in general so bear with me if i am missing the point somewhere. The main thing i do not yet understand / see is how to get memory from a compute ...
27 views

### Implementing monte carlo path traced refractions problem

I am writing a forward monte carlo path tracer with the added feature of specular refractions for transparent materials, I have managed to come this far but something is not quite right and I am ...
12k views

### Why are quads used in filmmaking and triangle in gaming?

In film school, in the classes of 3D modeling, I was told that when we model something for films we maintain topology of 4 edged polygons. Any polygon which has more or less than 4 edge/vertex is ...
68 views

### Why does the red color channel lose the most details during jpeg compression

I have an e-commerce website dealing with flowers and cakes. We get our photoshoot done inhouse and also the post-shoot editing of images. While we upload them on the website all images go through the ...
303 views

### Where should the ray origin be put in perspective camera ray tracing?

Where should the ray origin be put in perspective camera ray tracing? The following gives a picture of the ray tracing in the perspective camera setting: https://www.cs.cornell.edu/courses/cs4620/...
14 views

### How to transform x-y-z red-green-blue arrows and draw them on 2D screen?

I'm making a raytracer and want to print debug arrows Blender example: Old version of 3d max: How do I do the same having camera forward, up and right vector? I think I need some kind of matrix ...
35 views

### Best practice for managing many shaders and merging multiple shaders into one?

I have managed to greatly minimize draw calls on my recent project, but as I'm adding more shaders, I see that I have to switch more times and that is causing a lot of draw calls. What is the best ...
63 views

### Local Coordinates of Deformed Lattice

I'm making a lattice based volume FFD and I'm having trouble with gaps in my data resulting from doing a typical deformer. I think I need to go through the voxels in the deformed lattice and then find ...
45 views

### Groupshared memory and parallel reduction over multiple kernel dispatch

I am doing some parallel reduction and mostly following these nVidia slides. However they are not very detailed in places or I might be missing/misunderstanding something. Edit 2: While I figured ...
27 views

### HSI color space and RGB color space relationship in Steganography

I need to embed text in an image, research papers say HSI produces better mse and psnr therefore are better for steganography. I have RGB values(69,223,90) and its corresponding HSI is (127.223,0.458 ,...
598 views

### Phong: Real-time rendering of Metal and Plastic Materials

Using a shader that works like Phong, what would be the difference between painted Metal and plastic? I seem to remember reading in books years ago, that I no longer have access to, the following: ...
32 views

### An equation about PDFs and differentials in the book of pbrt-v3

Why does the equation at the bottom of the following page hold? http://www.pbr-book.org/3ed-2018/Monte_Carlo_Integration/Transforming_between_Distributions.html \$p(\theta,\phi)d\theta d\phi=p(\omega)...
370 views

### How can I raytrace a scene that does not fit into memory?

If the scene to be raytraced cannot be stored in memory, then without adding more RAM to the machine it seems unrealistic to render it in a practical time span, due to the need to load different parts ...
55 views

### Coloring arbitrary closed regions

I'm trying to implement the following paper in modern OpenGL http://web.media.mit.edu/~lieber/Publications/Coloring-Book.pdf The issue is that the algorithm described requires you to consider ...
33 views

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### Can you use OpenCV Stereo 3D Reconstruction with iPhone cameras to approximate LiDAR?

If the iPhone had LiDAR sensors, it would be possible to generate a 3D point cloud that you could theoretically use to furnish a 3D AR reconstruction of your surroundings. E.g. you could create an AR ...
113 views

### 3D object to slices like in medical scan

I am novice lacking professional terminology. I want to create from 3D object (let's say from polygon mesh) a slice through to PNG file in order to create something like reverse medical MRI scan from ...
600 views

### How correct is rendering in XYZ / linear RGB space?

I have a spectral power distribution (SPD, 5 nm steps) for all light sources in the scene and SPDs for the reflectance of all surfaces under any light / viewer angle in question. I'm going to ...
84 views

### Shader that transforms a mercator projection to equirectangular?

I am new in the OpenGL - GLSL and trying to make a shader that taking a mercator projection texture as a source and converting it to an equirectangular projection texture. Sample input: (1024x1024) ...
53 views

### What's more optimal - sampling one channel at a time or all channels at once?

I'm going through and optimizing some of my glsl code for a project, and have come across a scenario several times that I am not sure how best to optimize. In summary - Is it faster to sample a ...
81 views

### Weird glColor3f results in framebuffer objects

The code is glColor3f(1, 1, 1); gluSphere(gluq, 0.2, 10, 10); glColor3f(1, 0, 0); glTranslatef(1, 0, 0); gluSphere(gluq, 0.2, 10, 10); In short, when I draw ...
14 views

### How Quantum works exactly in MagickCore?

It's been long I have been trying but I guess I will give up now, I am not able to understand some stuffs + documentations seem wrong. For example, In Magick++, the QuantumRange equations they ...
58 views

### Help me understand the voronoi shader

I am trying to understand the voronoi shader implemented in the Book of Shaders in the Tiling and iteration section: https://thebookofshaders.com/12/ Specifically how do these lines calculate the ...
29 views

### C++ code to subdivide skinny 3D triangles into more regular triangles

I am currently in the search for a C++ function that takes a triangle and some input control data (e.g. max area) and returns a list of triangles that are as equilateral as possible. I know there are ...
27 views

### How to get “Equal” (saturation, brightness) Red and Green Colours in a Web-based Application?

I am looking for a red and a green hue that are equally discernable against a gray background on any PC monitor, using HTML/CSS-based application. There are many possible solutions to balance these ...
64 views

### Creating glsl library

I have different functions for example normalmapping which I use all the time... Now I thought about making a small glsl library. My problem: I don't want to have all functions within the same "...
36 views

### Early depth test in WebGL

I understand that in OpenGL early depth test can be performed in the rasterizer (before running the fragment shader), but is it the same case for WebGL? If so, how is early depth test enabled in WebGL?...
12 views

### Custom Create Maps in OpenGL

I am trying to create some procedurally created terrains for which i need to create noise maps. How do I create a texture of noise map in OpenGL and then pass that in my vertex shader as a heightMap? ...
27 views

### How to properly combine diffuse and rough specular BRDFs in a path tracer

Looking around here on various sources (including related questions on this site), if my understanding is correct, when implementing a path tracer with a material which has both a diffuse term and a ...
87 views

### How can I raycast with chunks?

I am attempting to implement chunks/octrees to speed up my render times. However, sometimes the walls show horizontal or vertical lines (rays hitting the inside of voxels?) or some blocks disappear ...
8 views

### Debugging Python OpenGL apps

how do I debug OpenGL apps written in python? I tried but I was unable to use standard tools like nvidia nsight or glsl-debugger or renderDoc on python code. Are there any specialized tools for ...
30 views

### How to find the BRDF of a rough specular surface

So I know that the BRDF for a diffuse material is `albedo/π', and I know that the BRDF for a perfectly specular surface is only non-zero on the reflected direction. How would I find the BRDF for a ...
25 views

### How to convert from XYZ or sRGB to ACEScg/AP1

I'm confused about how to properly convert from sRGB or XYZ color space to ACEScg. Specifically whether I have to account for differences in white point explicitly. The aces github page gives the ...
40 views

### Is it viable to create computer graphics via terrain scanning?

Couldn't find any resources on this, so I'll ask here. For example, I want to create a game model of a mountain peak. I took lots and lots of drone footage, almost from every side, photography ...
48 views

### Weird patch on reflective spheres on planes in raytracer

I am writing a small raytracer in python , everything was working fine but when i implemented plane geometry then the reflective spheres are getting weird patches on lower bottom. image below: I ...
23 views

### Analytical derivative of a 3D Simplex Noise field

I am using Simplex Noise to generate a 3D field. The specific implementation is FastNoise-SIMD. Assume I want to have a gradient (or derivative) for a sample at Sx, Sy, Sz in that field. Do I ...