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2
votes
2answers
14 views

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. ...
2
votes
0answers
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 ...
1
vote
0answers
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 ...
1
vote
1answer
90 views

Sharing memory between compute shader and pixel shader

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 ...
2
votes
0answers
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 ...
15
votes
6answers
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 ...
2
votes
2answers
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 ...
1
vote
1answer
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/...
0
votes
0answers
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 ...
3
votes
0answers
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 ...
0
votes
1answer
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 ...
2
votes
0answers
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 ...
1
vote
0answers
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 ,...
4
votes
2answers
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: ...
0
votes
0answers
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)...
12
votes
4answers
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 ...
3
votes
2answers
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 ...
3
votes
1answer
33 views

Operator associativity and 4x4 matrices - performance question

During vertex processing with 4x4 matrices, we might stack multiple transformations like projection, model-world, world-camera, etc. by doing something like this: $$v_{final} = T_N \cdot ... \cdot ...
3
votes
0answers
34 views

How do I make sure my cosine-weighted sampling works fine?

I'm working on a pathtracer and while it's working mostly fine, I'm getting different outputs with cosine-weighted sampling and uniform sampling : Uniform sampling is on the left, cosine-weighted is ...
0
votes
1answer
93 views

What is wrong with my metalic PBR shader?

I feel like my light conservation math isn't correct, but I am not sure which part is wrong. Is reflected light supposed to influence the diffuse light? Does metalness only affect the reflected ...
4
votes
3answers
87 views

Visualize the interpolated unit quaternion on the surface of the unit sphere

My major is mechanical, please forgive me for asking questions that may seem trivial to you. First, I'm reading the following paper: Dam, Erik B., Martin Koch, and Martin Lillholm. Quaternions, ...
1
vote
1answer
77 views

Problem on understanding gamma correction

I am struggling understanding gamma encoding/decoding. So the colors I see and the values I get from a color picker application(like MS Paint) are already in sRGB space(correct?). Assume the color ...
1
vote
1answer
60 views

Export Model Textures Per Face

(Note that as far as attempts go, I can't find anything that helps me) I have a 3D polygon, and for simplicity's sake it's going to be the one below: It is textured using the UV map below: Side ...
3
votes
0answers
58 views

volume raymarching - aligning sample coords with the 3d texture

I'm implementing a volume raymarcher and the unlit basic version seems to be working fine. This article helped a ton grokking the view-to-volume-space transform: http://www.lebarba.com However, it ...
2
votes
1answer
34 views

With vsync enabled where does the wait happen in OpenGL?

When having vsync enabled I'm imagining that OpenGL has an explicit wait function to try and keep the frame rate constant. If so where is this function implemented exactly? After running some tests <...
2
votes
0answers
30 views

Normalization technique to increase spread of data in rgb space

I am visualizing a dataset. My technique is to encode the data into a rgb image with the channel range [0, 255]. The data clusters in a narrow range relative to [0, 255], however, so I'm not getting ...
1
vote
1answer
66 views

Linear independence of three points

What is the best way to prove if three points are linear dependent? This is my current way to do it: $$\mathbf{v_a} = \mathbf{b}-\mathbf{a} \\ \mathbf{v_b} = \mathbf{c}-\mathbf{a} \\ \mathbf{v_c} = \...
0
votes
0answers
20 views

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 ...
1
vote
2answers
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 ...
11
votes
1answer
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 ...
3
votes
1answer
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) ...
1
vote
2answers
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 ...
1
vote
1answer
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 ...
0
votes
0answers
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 ...
1
vote
1answer
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 ...
0
votes
0answers
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 ...
1
vote
0answers
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 ...
2
votes
1answer
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 "...
0
votes
1answer
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?...
0
votes
0answers
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? ...
1
vote
0answers
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 ...
2
votes
1answer
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 ...
-1
votes
0answers
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 ...
1
vote
0answers
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 ...
2
votes
1answer
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 ...
0
votes
1answer
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 ...
0
votes
2answers
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 ...
3
votes
0answers
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 ...
1
vote
1answer
48 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 ...
0
votes
0answers
30 views

What are some uses for the vector triple product in computer graphics?

I have just learned about the vector triple product (Lagrange formula) from a math for computer graphics textbook, however the book does not mention any use cases for it beyond the fact that it's a ...

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