All Questions
3,963
questions
0
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0
answers
32
views
Rotating a set of cameras to look at a rotated object
I'm trying to use Instant NGP on a synthetic image dataset. I have image sequences of a moving object with the following information:
I have the object's xyz and the camera's xyz positions in a void.
...
- 1
0
votes
1
answer
35
views
What's the intuition behind color burn and other blend modes?
I've implemented a simple color burn function in one of my shaders and I understand the results (I think), but the math behind it, although simple, is unintuitive to me. I struggle to understand how ...
-1
votes
1
answer
159
views
How to send data from a C# application to a C++ DLL?
I have a C++ graphics engine and I would like to build an editor for it in C#. I want to be able to send data from the editor to the engine such as what tool is being used and any user-defined ...
- 2,491
1
vote
1
answer
135
views
Importance sampling of the blinn-phong brdf in pathtracing
tl;dr:
How do you importance sample the blinn-phong-brdf?
Recipe for importance sampling of the phong brdf as far as i understood it (pseudo-code):
...
- 11
0
votes
2
answers
40
views
Finding vertices of a polytope?
Assume that in 3D we have a polytope defined by the intersection of halfspaces.
A half space is the set of all solutions of a linear inequality $P = N \cdot x + c \leq 0$ Where $N$ is the normal to ...
- 1,696
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votes
0
answers
50
views
"Smoothing out" raymarched reflections
I am writing a program to display 3-dimensional lattices (honeycombs) using raymarching and reflections. I made a simple cubic honeycomb to start. The usual method is to use a repetition operator, by ...
- 101
1
vote
1
answer
54
views
Confusion about the bias during Monte Carlo integration
I recently stumbled into this question:
Say, for example, we are doing mean-free-path sampling (distance sampling) in a scattering medium and to keep it simple, let's only consider the single ...
- 575
1
vote
3
answers
136
views
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 ...
1
vote
1
answer
32
views
Automatically convert field of white and an outline to transparent background
I'm trying to convert images that have a single object with an outline to a transparent background. I'm currently using the image/png package in golang but can switch to any language thats more ...
- 11
0
votes
0
answers
33
views
3D engine projection distortions
I'm trying to write my own 3D engine using Python and Pygame.
I have successfully implemented rotation and projection matrices to display 3D models. However I am so far unable to implement translation ...
- 11
0
votes
1
answer
44
views
Why capsule box intersection algorithms not widely used
I have searched through a lot of libraries and sources, that include very diverse intersection algorithms, for computer graphics. And I've never found a capsule-box intersection algorithm. Despite ...
- 516
0
votes
0
answers
77
views
Vulkan: Compressed image formats and mipmapping
I am currently grappling with the computation of mipmaps for block compressed formats (BC7) in Vulkan. The limitation with these formats is that the size of the block compressed texture needs to be a ...
- 1
1
vote
0
answers
54
views
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 ...
- 171
0
votes
1
answer
50
views
Methods for filling the area between complex curves
I'm looking for algorithms or methods suitable for filling the area enclosed between complex curves - for example, the area within an outer ellipse but outside an inner ellipse, or the area bounded by ...
- 101
0
votes
1
answer
75
views
What is the theory behind a CPU being able to do everything a GPU can? Can I have something GPU based that can not run on a CPU?
GPUs have a smaller instruction set than a CPU does, but that means that from an architecture POV all the instructions in a GPU have a combination of slower CPU equivalent instructions?
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0
answers
49
views
Computer Graphics Previous Year Question asked in UGC NET 2021
What is the transformation matrix M that transforms a square in the x-y plane defined by (1, 1)T (-1, 1)T (-1, -1)T (1, -1)T to a parallelogram whose corresponding vertices are (2, 1)T (0,1)T (-2, -1)...
- 101
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0
answers
50
views
Is it possible to scale a view matrix?
My world has the base unit of 1024. Each tile is 1024x1024 units.
When the camera is at the center of a tile, the tile ranges from -512 to 512 in view space (no rotation).
Does it make sense (and is ...
- 171
1
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0
answers
51
views
How do freehand vector drawing tools typically decide where to place the control points?
I'm devising an algorithm to take a freehand curve and make a bezier spline from it. I can do this already just fine, but it's a naive implementation that creates about as many bezier curves as there ...
- 142
1
vote
1
answer
104
views
What is out-of-core raytracing?
I just stumbled upon this "out-of-core" term and tried to see what it is about. There are a few papers and even a few questions talking about it here at computergraphics.stackexchange, but I ...
- 1,541
1
vote
0
answers
42
views
Measure for volumetric rendering equation
Recently I've been digging deeper into the volumetric rendering (volumetric path tracing, to be specific). I already know that for surface rendering, there are two commonly used measures (reference ...
- 575
1
vote
1
answer
278
views
Game texture looks pixelated at big distance
I'm currently making a game with Python's Ursina module, and everything runs well, except:
the grass texture (size: 8192x8192px) looks pixelated at big distance (everything inside the red marker). How ...
- 11
1
vote
1
answer
101
views
What is the "kernel" in learnopengl SSAO tutorial?
I am currently reading the SSAO tutorial on learnopengl.
In it, there is a "kernel" that has the dimension of 64 and contains ...
- 171
1
vote
1
answer
123
views
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 ...
- 13
2
votes
0
answers
51
views
Volumetric Renders become brighter as the focal length changes
Before we start, I have to warn yall, this program was written in VEX. Which is a programming language for Houdini. So it is a language within a 3D software. Its not really meant for this sort of ...
- 121
0
votes
1
answer
46
views
How to set Vulkan Validation Layer filter via the vk_layer_settings.txt?
I have just activated the Vulkan Best Practices Validation and due to that I get the following warning:
Validation Layer(WARNING): Validation Warning: [ UNASSIGNED-BestPractices-vkCreateInstance-...
- 1,541
0
votes
0
answers
49
views
Floating point precision in 3d modeling software
I'm working on a simple 3d modeling application. I'm using 1 meter as unit of measurement. When working with small triangles where an edge length is around 1 centimeter (0.01 units) or less, I started ...
- 516
0
votes
1
answer
62
views
Patchy patterned artefacting in depth buffer
I am writing a polygon rasterization renderer. Some meshes render flawlessly, but some produce strange artefacts in the depth buffer. These artefacts do not just appear when I save the depth buffer ...
- 3
2
votes
0
answers
42
views
How to properly use scattering coefficient during volumetric path tracing?
The increased radiance during sampling is known by:
$$
L_s = L_e + \sigma_s \int p(w, w')f_p(w, w')dw'
$$
The latter part, which accounts for in-scattering radiance bears a $\sigma_s$ in it.
The ...
- 575
1
vote
1
answer
126
views
is there an universal way to set a uniform?
so I'm working on a game engine.
It's partially python and c++.
One part that is currently a pain point is setting the uniforms for shaders.
Currently I have to define a behavior for all 50+ methods ...
- 13
2
votes
1
answer
75
views
How can I get an Irradiance or power value from RGB?
is there a way to output the power in watts from an R, G and B value? I know there are many formulae to get perceived brightness but is there one to get an objective amount (relative or otherwise)?
...
- 21
1
vote
1
answer
69
views
What is the name for a film overlay where there is an array of crosses?
I've seen this in a lot of animations of spaceships, as well as the intro sequence to The Expanse which I've attached a screenshot of. https://vimeo.com/734114243 is also an example.
The above ...
- 33
0
votes
0
answers
40
views
0
votes
0
answers
94
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 ...
- 575
0
votes
2
answers
125
views
Where does sin(theta) go in estimators of The Rendering Equation?
Consider this equation, where we have a surface integral over hemisphere with Lambertian BRDF and cos(theta) from The Rendering Equation:
$$
\int_{0}^{2\pi}\int_{0}^{\frac{\pi}{2}}\frac{albedo}{\pi}...
- 125
0
votes
2
answers
123
views
Storing array of floats within shader
I am about to implement a framerate histogramm chart for a DirectX Renderer.
Ideally I would do this in pure shader code, but for a a histogramm I need to store the timestamps of the last ...
0
votes
0
answers
69
views
Defining ray direction vector
Here I try to combine scratchapixel's articles to understand the operation of the camera-to-world matrix and ray direction vector. Here https://www.scratchapixel.com/lessons/3d-basic-rendering/ray-...
1
vote
1
answer
48
views
Question regarding texture mapping sampling
I am new to computer graphics and have taken up a course in my university on computer graphics. Need help regarding a question as I could not find any relevant resource on the internet so hoping the ...
- 13
0
votes
0
answers
39
views
Does sampling GGX VNDF take into account the cosine incidene of outgoing ray?
Could sampling GGX VNDF sampling,
based on:
"Sampling Visible GGX Normals with Spherical Caps" and
"Sampling the GGX Distribution of Visible Normals"
produce a normal that (based ...
- 730
0
votes
1
answer
69
views
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 ...
- 3
1
vote
1
answer
105
views
Is glDeleteBuffers/glGenBuffers needed if I want to resize the buffer?
Firstly the VBO was initialized like below:
...
- 13
0
votes
0
answers
29
views
Why does my screen flicker when scrolling the image below?
I'm not sure if this is the correct place to ask this, but does anyone here know why my screen flickers (not in a broken kind of way) when scrolling on this image from Claude Mellan
- 101
1
vote
0
answers
55
views
What is this cardioid/fish-like graphic that appears in FFXVI when looking at the sun?
In Final Fantasy 16, a recent video game, when looking towards the setting sun, one sees several circles, which seem like the lens flare that one commonly sees in games. But the most prominent (circle)...
- 111
0
votes
1
answer
46
views
Position a 3D camera directly above or below the target
I'm trying to setup a 3D camera in WebGL. The camera is setup with the help of a lookAt function. The lookAt function takes cameraTarget, ...
- 127
1
vote
1
answer
87
views
Move the camera in orthographic 3D
I'm trying to figure out how to move a camera in orthographic 3D. The scene is orthographic in the sense that an object looks the same regardless of position. The only thing that may affect the size ...
- 127
0
votes
0
answers
17
views
How can I generate a reflectance map using a perspective camera?
In simple words, a reflectance map is a function f(n) that map a surface patch with normal n to its reflected radiance given a ...
- 119
1
vote
1
answer
51
views
Shading normal and geometric normal for refractive surface rendering
I got confused when implementing my own renderer. I read this from the PBR-book:
Fortunately, there is an elegant solution to these problems. When evaluating the BSDF, we can use the geometric normal ...
- 575
1
vote
0
answers
25
views
How to solve GGX roughness from existing maps
I have a problem that I cannot really wrap my head around.
I have a minimal light stage setup to scan heads:
I have cross polarized cameras and parallel polarized cameras.
I have parallel polarized ...
0
votes
0
answers
48
views
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 <...
- 11
0
votes
1
answer
221
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&...
0
votes
2
answers
92
views
Glitches with raymarcher shader
I have been programing a simple ray marcher with GLES, using The Book of Shaders editor. I noticed that on scenes with multiple objects (multiple SDFs), I am getting glitches on edges of object which ...
- 111