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86 views

Procedural Generation of 4D Shapes

I'm curious if anyone has any insight into how one might procedurally generate 4D objects, as showcased in Miegakure (or the developer's other game, 4D Toys ). I built a program a while back to do ...
0
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0answers
74 views

Relation between camera sensor responsivity and image reconstruction filter associated with a pixel

Let $W_{\text e}$ denote the camera sensor responsivity (i.e. importance) and $h_j$ and $W_{\text e}^{(j)}$ denote the image reconstruction filter and sensor response associated with the $j$th pixel, ...
0
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1answer
69 views

Data structure of IFC-files

I know OBJ-files essentially are one or more lists of n-tuples containing information about the location of vertices, texture and normals. However, I am not sure how this is structured in an IFC-file. ...
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0answers
22 views

Convolution of multiple gaussian filters with different sizes

What is the size of the final filter after implement convolution of multiple gaussian filters with different sizes?
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1answer
97 views

Properties of the image reconstruction filter in rendering

Let $f$ denote the measurement contribution function for paths of length $k\in\mathbb N$, i.e. $$f(x)=g(x_0\leftrightarrow x_1)W_{\text e}(x_1\to x_0)t_k(x_0,\ldots,x_k)L_{\text e}(x_k\to x_{k-1}),$$ ...
1
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0answers
34 views

Sampling the depth component of a packed depth-stencil texture while rendering to its stencil component

I need to frequently perform depth testing for any given fragment at a different fragment location than the one rendered to. Since this isn't possible with normal builtin OpenGL depth testing ...
2
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0answers
134 views

Scaling of the final image in Metropolis Light Transport

I don't understand why the PBR implementation of Metorpolis Light Transport scales the final image by b / mutationsPerPixel. The authors write: Each Metropolis ...
0
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1answer
48 views

Determining shortest vector between a ray and an axis-aligned 3D bounding box (correcting a near-miss)

I have a situation where (due to floating point error) a ray that is known to hit a bounding box fails due to floating point error. (1e-8 or so) Expanding the box is not an acceptable solution in my ...
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3answers
188 views

perspective matrix derivation

Now there has already been an answer here in this stackexchange, but I don't understand certain aspects of it. The author has MORE DETAILED DESCRIPTION HERE(#1) but the problem is he doesn't describe ...
0
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1answer
68 views

Graphics engines during the sixth console generation

From my understanding game developers used mostly proprietary, in-house graphics engines during the sixth console generation (Xbox, PS2, GC, DC) on a game to game basis. Why didn't standard engines ...
1
vote
1answer
47 views

Extracting information from EXR Files

I am relatively new to computer vision and image processing. I have a single EXR file with 7 channels: 1-3 give me the RGB values, 4-6 give me the surface normals coded as RGB values and 7th channel ...
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0answers
85 views

how is zooming done in computer graphics

Since a projection plane and a center of projection is used for achieving perspective projection, the shape of the view frustum doesn't change changing the focal length(which is the distance from the ...
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0answers
28 views

Loop subdivision, certain areas converging towards degenerate geometry

I coded loop subdivision and ran it on a cube with triangle faces. I noticed this: I am using doubles to represent my vertex positions, I am not 100% sure these are caused by floating point ...
0
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0answers
53 views

What is it that really prevents photo-realistic, real-time, digital 3D simulations?

Ever since I was a small child, seeing the amazing 3D visuals that developed in the 1980s and 1990s, I was certain that photo-realism was "just around the corner". In the year 2020, I certainly ...
2
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0answers
28 views

Quantify the variance of pixel measurements

Say $E_j$ is an estimator of the value $$I_j=\int f_j\:{\rm d}\lambda$$ of the $j$th pixel given by the path space integral of the corresponding measurement contribution function $f_j$. $f_j$ is of ...
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0answers
33 views

Is casting a shadow ray non-symmetric in pbrt?

According to the description in the book, Scene::IntersectP() "checks for the existence of intersections along the [passed] ray". This operatorion should be ...
0
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1answer
90 views

Sending programs from CPU to GPU

How does a CPU know which piece of code should be executed on GPU (i.e how to recognize whether a code is shader or not) and how is it been sent to GPU VRAM?Is it via DMA?
1
vote
1answer
63 views

How to handle Half edge boundary edge iteration from vertex?

Ok so let's say we have a portion of a mesh that looks somewhat like this: A triangle fan with one of the triangles removed. If that triangles was not removed, we could get all the edges adjacent to ...
0
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0answers
41 views

Case where ray hits corner of box

I am writing a path tracer and when wrting method for returning the normal for the plane that was hit, I am not quite sure what to do when the ray hits box in a corner, placing the intersection point ...
0
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0answers
46 views

Formula for non area light BRDFs

I'm reading a graphics book and it talks about BRDFs being the ratio between differential outgoing radiance and differential irradiance. The formula it gives is f(l, v) = dL(v)/dE(l) Where l is the ...
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0answers
55 views

Understanding Oren-Nayar reflectance model

In the Oren–Nayar reflectance model, each facet is assumed to be Lambertian in reflectance. wiki My understanding : Law of reflection tells us that angle of incidence is equal to angle of ...
0
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0answers
51 views

Mesh boolean and amount of triangles

Inspired by BSP tree mesh operations, I've implemented an operation that takes a mesh X, a BSP tree/sequence of planes, and creates a new mesh, by iteratively slicing mesh X by these planes in some ...
2
votes
1answer
93 views

How do people come up with subdivision schemes?

Be it chaikin subdivision, loop subdivision, catmull-clark subdivision... How do people come up with the coefficients for an arbitrary subdivision scheme?
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0answers
80 views

Shader sampler2D uniforms instead of attributes

In the godot game engine (using opengl) it is not possible to define custom shader attributes. A workaround is creating a sampler2D texture uniform instead and use vertexId (or in fact UV since ...
1
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0answers
37 views

How do I fix skipping ray-triangle intersections on concave edges/cavities of model?

I'm writing a path tracer and I have a problem with ray-triangle intersection tests. The problem happens most frequently with materials that implement random scattering of the ray. Here's a function ...
0
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0answers
33 views

Problem with Quad-based Tessellation in GLSL generating incorrect vertex ordered tessellation

I am trying to perform quad-based tessellation using GLSL on Unity to be able to render polynomial-based parametric surfaces on a Unity quad. The quad-based tessellation using GLSL seems to be ...
1
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0answers
46 views

Implementing the derivation of the Smith Shadowing function for arbitrary distributions

I'm trying to implement the derivation of the masking function G_1 by Smith. The appendix of Walter et al 1, Hammons presentation 2 and this research paper 3 talk in detail about it and I feel as I do ...
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0answers
16 views

What are the options/limits for high definition live video streams?

Assume we have a small computer (for example the Tegra Xavier board from nvidia), which is connected to a second computer. On the small computer we have a new frame in raw format. We want to send ...
0
votes
1answer
68 views

basic of image dithering

Is just read about image-dithering ? So I tried to implement that. Here is my result. Can someone verify it? My code : ...
1
vote
1answer
73 views

Defining “inside” and “outside” of a 3D space

I am not sure if this is the correct SE to ask this question. However, lets say I have been given 3D models of several enclosed spaces. I want to populate spaces with, lets say, planes flying through ...
0
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1answer
124 views

Which technique should be used for rendering under water images, Ray tracing or Radiosity?

Rendering is the process of computing a three-dimensional geometric description of a scene into a two-dimensional image representation that looks real. Ray-tracing and Radiosity are two of the most ...
0
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0answers
15 views

Turning layered curves to polygon mesh?

I am confronted with the problem to render 3D representations for objects marked on microscope slices. So I have a set of aligned polygons in parallel planes from tracing the outline of the object in ...
2
votes
1answer
45 views

How to subdivide faces with a half edge DS?

Assume we have a mesh represented as a half edge datastructure. We want to subdivide faces without introducing unnecessary vertices (i.e the new number of vertices must be exactly V + E where V is the ...
2
votes
1answer
37 views

2D array texture with different filtering setting per texture?

Currently I have textures which need GL_NEAREST and some other need GL_LINEAR in the same texture2dArray. In the shader I perform a manual GL_NEAREST lookup via textureFetch(). To avoid this my ...
0
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2answers
61 views

How does graphics api like OpenGL determine which triangle is back face to cull?

When I was writing a software rasterizer for my university class, we did culling in eye coordinates. Essentially, we use cross product to get a normal from the 3 vertices (in eye coordinates), then ...
0
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0answers
103 views

Unable to implement firebaseui auth in android app

i was trying to integrate firebase authentication in my android app using implementation 'com.firebaseui:firebase-ui-auth:4.3.1' but i am getting the errors: <...
3
votes
2answers
110 views

Need a fast ray-box intersection that handles if a ray is parallel and in line with a plane of the box

I've seen lots of spins on the ray-box intersection test, and a lot of them seem to boil down to this code: (omitting some details here) ...
0
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0answers
22 views

Algorithm to reproject texture after wrapping mesh using ICP?

I was watching this video, where given a base mesh we wrap it in a scanned mesh, I can imagine how to implement something similar from scratch, but I was wondering how can I assign uv coordinates to ...
1
vote
2answers
43 views

Blackbody curve to floating RGB

I want to set the color of the lamps in my game with a black body curve, but the approximations I can find for it are all in sRGB color space; and I want it in linear floating RGB. The closest thing ...
2
votes
1answer
147 views

Sampling the light vs. sampling the BRDF: difference in intensity

(possible duplicate) I'm trying to implement multiple importance sampling, as described in the PBRT book (no bouncing yet, I want to make MIS work first). What my problem is, that while the BRDF ...
0
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0answers
26 views

void* D3D11_MAPPED_SUBRESOURCE::pData to OLE_COLOR* possible?

I have found the following from this link enter link description here pData Type: void* Pointer to the data. When ID3D11DeviceContext::Map provides the pointer, the runtime ensures that ...
0
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0answers
16 views

Explanation request for a GDI code block

I have a small old code snippet where I am not sure what is actually someone wanted to do. As I am not doing and trial and error guessing dvelopment. I have to be certain about the purpose could do ...
1
vote
2answers
45 views

Y axis inversion in 3D rasterization

What is the correct way to invert the y axis during the 3D projection? I see a lot a people doing: ...
0
votes
0answers
41 views

Find the inside and outside relationship of connected components in a mesh

I extract a mesh from a method similar to Marching cubes. I want to estimate the topological relationship between connected components. For example, below, let's assume that we have 4 connected ...
3
votes
1answer
49 views

Understanding distinct vs. not distinct knots in B-splines

In reading the wikipedia page about B-Splines https://en.wikipedia.org/wiki/B-spline, I am getting confused about the concept of knots. If we have a spline of order $n$, with a knot vector ($t_0, \...
0
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0answers
44 views

Non linear transformation of vector graphic

I want to do a non-linear transformation of a svg in python. My specific problem is to transform a rectangular svg image into a frustum like image, for which i have a mathematical equation of the form ...
1
vote
0answers
90 views

Why does Schlick's approximation contain a \$(1-\cos\theta)^5\$ term?

The approximation writes the reflection coefficient as$$R(\theta)=R_0+(1-R_0)(1-\cos\theta)^5,\,R_0=\left(\frac{n_1-n_2}{n_1+n_2}\right)^2.$$Why is the exponent 5? Schlick 1994 introduces this ...
0
votes
0answers
42 views

Rotation around local axis

I am trying to understand rotation and I come across the scenario of rotation with respect to the object itself. One strategy that makes sense to me is that I would translate and rotate one of the ...
0
votes
1answer
69 views

Is there a term to refer to a cube-break-down process?

The image shown below illustrate the process to break a cube down into 4 small equal cubes. Is there a term to refer to this process, something like cube-break-down? Why would I like to know the ...
0
votes
1answer
68 views

Reading thesis on cone tracing, did the author make a mistake?

I am reading this document that talks about signed distance field rendering. In that document section 6.3, on the topic of cone tracing, it says: Cone tracing is an extension of the sphere tracing ...

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