# All Questions

2,228 questions
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### Confused on reflection coeffcient of Fresnel equations

I am reading a paper about layered materials. However, I am confused on the implementation of this paper. The following picture describe the layered material. r_ab is a complex reflection coeffcient ...
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### How to create planar slices of voxel shapes?

I would like to create many komplementer planar slices of simple voxel shapes and than export the results to png. Eg. a voxel sphere, cone, cube, ... cut to 4 pieces by 2 planes so that the no voxel ...
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### Non ray-traced Crepuscular rays/Under water godrays what *angle realistic* methods can I use?

I'm trying to figure out how to render under water godrays, I've found numerous methods that use things like rendering fake caustics via ray marching through the medium, collecting values based upon ...
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### Bump mapping with triangles and heigt maps

I'm trying to add bump mapping to my ray tracer, and I'm currently struggling to add bump mapping to it, as I don't seem to get the transformations from texture space to world space correctly. I have ...
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### Efficiently drawing multiple instances of 3D objects

I was able to write the following working code to draw any number of "sprites" (defined as 2 tringles, 6 vertices) ...
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### If you can use subdivision surfaces for 2D curves

I've seen how subdivision surfaces are good for 3D curves/modeling, but haven't seen anything on if it's good, or even usable, in 2D. My question is just that, if (a) you can even use subdivision ...
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### What algorithm is used in this animation from Tatami Galaxy?

Is there a name for this type of effect where many area sizes are increased/decreased in relation to each other? I'm looking for some type of algorithm, formula, logic, etc. for recreating this. Here ...
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### Understanding threshold finding in the Hough space in Python

I am following a tutorial on writing a Hough algorithm in Python: to my understanding it is very well written but I am new to computer graphic algorithms (not really used to thinking in terms of ...
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### Problems with Subdivision Surfaces

It sounds like Subdivision Surfaces are better than NURBS but not as good as T-splines. I would like to know some of the disadvantages of Subdivision Surfaces, what they can't do or what they do ...
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### Why do perspective correction based texture mapping do depth division

I'm currently trying to understand how works perspective correction texture mapping. I saw that actually it works by interpolating the z value of the three point of the triangle which the current ...
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### Mesh vertex to point cloud conversion? [on hold]

I need to convert all the vertices of a mesh to points in a point cloud. (Ideally a PLY file, or what a PLY could be converted from.) I need the colors from the mesh's vertex color channel or ...
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### How to calculate ray

In ray-tracing technique critical point is to calculate rays which came out from eye $E$ to target $T$ through pixel $P_{ij}$ on viewport. The "viewport" is represented as rectangle divided to square ...
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### Large movement in videos causes green and red shadows [on hold]

When I'm playing videos, in some videos, when a large amount of movement happens, a green and red copy of whatever moved appears. Also when I press play, a green glitch appears at the bottom of the ...
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### Crop equal sized portion from the image

I want to crop each small plot of small green patches from the field but I am unable to figure out , how to do it in a non-brute force way .Also , how could I crop equal portion of the image as the ...
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### How to detect if a text is mirrored in an image using opencv?

I was working on an application to perform OCR on an image. For performing OCR, one has to make sure that the the patch of image containing the text is with correct attributes. I was able to fix all ...
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### Convex hull around polygon for cave mapping

For the purpose of mapping caves, we survey new passages so that we take main polygon (survey from point A to point B) and on each "node" (survey station A in example), we shoot multiple "splay shots" ...
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### How to get the 3D position for the point with (0,0) UV coordinates?

I have a 3D triangular mesh(vertices, indices, uv coords) that I'm rendering to the screen. Let's assume that the UV mapping is one-to-one. I'm trying to find a way to find the 3D position of the ...
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### Naive Path tracer produces much darker images than Explicit light sampling

So I just thought of comparing the results from a Naive Path tracer and one using Next Event Estimation aka Explicit Direct Light Sampling. However the results from the Naive PT are very dark. Is ...
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### Can't understand the Importance sampling GGX

I've read many articles relating to importance sampling of GGX. However, I still feel confused. The formula of GGX is : And many article says we should use this formula to sample: In the formula, ...
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### How does a GLSL Sampler2D read a Vec2 UV coordinate to determine UV range

I am working with an atlas shader that steps through various sprite tiles within a single png atlas page to playback an animation with sampler2D. Looking at the shader code, I would expect to have to ...
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### Convert shader from GLsl 1.50 to 1.30

I'm a newbie with OpenGl and I'm stuck in following the tutorial. I found this tutorial with these shaders ...
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### What to reproject when doing temporal filtering in stochastic screen space reflection?

I am in the middle of implementing stochastic screen space reflection based on frostbite presentation here. On page number 39, it is stated that we need to reproject the ray intersection location ...
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### Why Diffuse Light use max(N · H, 0) instead of just letting it be negative?

In Cg tuts, Diffuse Section Surfaces that face away from the light will produce negative dot-product values, so the max(N · L, 0) in the equation ensures that these surfaces show no diffuse ...
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### Automatically picking the control points of a cubic B-spline

I have a linear timeseries which "looks" like a pseduo-sinosoidal function (\Inf -smooth, more or less regularly shaped peaks, gradual change in aplitudes, etc). I want to interpolate this function ...
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### Need help with change of basis (world to camera frame)

I'm reading up on coordinate systems and geometric transformations but the change of basis topic still confuses me. I found this exercise but, honestly, I wouldn't know how to begin: Given a world ...
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### Make a texture a clickable Button

What would be the best way to make a texture a clickable button? Suppose I have a Room (respresented by a 2D texture), where there are buttons. Would I in the main loop: check when the mouse is ...
62 views

### Why don't Direct3D/Metal support texture swizzles?

To be clear, I'm talking about behavior like https://www.khronos.org/opengl/wiki/Texture#Swizzle_mask, not "normal" myColorVariable.rbgr swizzling in a shader. I ...
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### Multiple Importance Sampling in Path tracer produces Dark Images

So I recently implemented Multiple Importance Sampling in my path tracer which was based on next event estimation. The problem is without MIS I get images like, This is obtained by setting ...
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### Texturing an “infinite” plane

I am rendering an infinite plane as described in the following answers: https://stackoverflow.com/questions/12965161/rendering-infinitely-large-plane https://stackoverflow.com/questions/7380250/how-...
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### Why does some text on my laptop have gray-scale pixels and some have color pixels?

In this question I generated the images below to explain why I can't use TTFs for that 1-bit display application. But now I would like to understand from the perspective of a non-expert, why is some ...
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### Comprehensive explanation of conservative rasterization algorithm

I am trying to implement conservative voxelization as part of real time GI in my hobby rendering engine. I find this article by NVIDIA. I am stuck at understanding the second algorithm. The problem ...
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### 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 ...
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### Composition of decomposed transformations

Say I have a scene graph, and each node has a scale, rotation, and translation. Can I combine these into a single scale, rotation, and translation?
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### Get intersection Ray with square

I have a class Ray and Square public class Rayo { public Point origen; public Vector direction; Square{ X,Y,Widht, height; } I need intersection between this ...
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### R16_FLOAT, SampleCmp and CheckFormatSupport

I want to use PCF shadow map on my d3d11 app. My shadow map is an R16_FLOAT texture. When I use SampleCmpLevelZero it didn't give a correct result. After enabling debug layer, it shows: The Shader ...
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### How to shift color values of a single RGB channel

I’m a weaver and textile maker with no prior coding or programming experience. In researching and reading through posts on this and other message boards, I was able to find a lot of useful information,...
30 views

### Bounded Biharmonic Weights alternative

Is there a more efficient alternative for BBW in the event of having only point handles rather than having cages and bones as well?
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### Rotate a model or a view with mouse input to produce intuitive results

I am writing 3D graphics software in Java using the LibGDX framework (which is a front-end for OpenGL), and am baffled by a transformation problem. How do I rotate the orientation of the camera or ...
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### What is best way to use wavefront material file color parameter Kd to set vertex color in MetalKit submeshes?

I am developing a MacOS program using MacOS MetalKit and ModelIO. The ultimate goal is to use the 3D model to analyze the acoustic properties of a performance space. Initially I'm just creating a ...
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### What does GPU serialized mean?

With GPU isolation : multiple processes use the single GPU will be serialized, cause OOM easily link https://www.slideshare.net/mobile/Hadoop_Summit/deep-learning-on-yarn-running-distributed-...
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### How much does driver quality affect Vulkan and DX12 compared to OpenGL and DX11?

Considering the fact that Vulkan and DX12 delegate most of the memory management / work scheduling tasks to the application itself, how much do drivers affect performance? To put my question into ...
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### Why MOCAP data don't use simple point coordinates?

This might sound stupid for you but I really don't know how it works in the domain of 3d animation and motion capture, but I need to work with ASF/AMC files at the moment and I find it a little bit ...
47 views

### Rendering Equation for photons carrying flux

I am trying to understand the mathematical/physical foundations of photon mapping better. In the forward photon tracing step it is established, that the rays are carrying portions of total power (...
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### 3ds max: Z-fighting when working with Large Objects

I had a z-fighting/z-clipping issue with a scene containing some very large objects yesterday in 3ds max. It can be seen in the image below: For some reason downscaling the scene significantly (a ...
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### How can I make a cube with faces of different colors? Webgl

I have to draw cubes with faces of different colors (each per face), but I don't know how to accomplish this task: I draw cubes using CPU and GPU meshes (no vertexBuffer or three.js "style") and I don'...
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### How can you avoid thin triangles in a parametric shape in a smart way?

I have created a closed 3D mesh using a parametric function. The shape is constructed by taking an arbitrary closed b-spline and scaling it based on one of the parameters (similar idea to a parametric ...
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### Bitmap-images or SVG

I'd like to create a GUI in my first Unity-game (2D). I want my GUI appear sharp in all resolutions (e.g. 1920x1200 or 3840x2160). The problem I am facing now is that I don't know if I should save my ...