Questions tagged [interpolation]
The interpolation tag has no usage guidance.
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interpolated normal vectors after tessellation. How to hash patch corner / edge vertices?
I have a 3D geometry (an asteroid) that is to be tessellated with respect to the camera position. Each vertex in the original mesh has a unique position and is stored once (VBO with IBO)
In the ...
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What is this method of interpolation / blending?
I am reverse-engineering two classes from a game. The two classes are responsible for generating sets of t values for interpolating / blending between two points through the formula:
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Undo barycentric interpolation
How do I undo the interpolation of vertex attributes? I'm using unity shader graph which doesn't support nointerpolation. I assume I need to store 3 float3 with one component of each float3 being 1 ...
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Calculating ray intersection with two spheres (with smooth_blending between the two spheres to make them appear as one continuous geometry)
I have the following function to define the distance to the interesection between a ray and the surface of a sphere:
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Float point placement with anti aliasing
I have an image of size H,W, and I would like to draw a point on this image at x,...
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Correct way to interpolate 1/z?
I have doubts on 1/z depth buffer interpolation. According to this website, the correct 1/z interpolation formula is
$\dfrac{1}{P.z} = \dfrac{1}{V0.z} * \lambda_0 + \dfrac{1}{V1.z} * \lambda_1 + \...
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How to make sure that triangles share edges (also not overlap each other) when rendering a quadrilateral?
Here is my simple scanline-based triangle rasterizer using pure integer arithmetic. I adapted the code from this Stack Overflow answer The below code attempts to render a coloured quadrilateral by ...
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Imprecise TEXCOORD interpolation of a screen quad in DirectX
I was debugging with RenderDoc an issue on an app based on Directx11 and 12 that draw screen space quads to perform various baking steps. These baking steps just render a quad in clip space without ...
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Smooth triangular mesh interpolation
I am looking for an algorithm which would smoothly interpolate triangles of a mesh (computed by Delaunay triangulation) where each vertex has some value (elevation in my case). I need it for PDAL ...
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What causes blobby edges with alpha testing?
I'm trying to understand what causes the blobby edges when using alpha testing to create transparency with 1-bit alpha channels. The edges appear pixelated, but with rounded corners and diagonal lines....
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Interpolating poisson disk samples in real time
If I have a regular sampling pattern there typically exist many reasonably fast ways to interpolate the results of the sampling procedure in between the sample locations. For example bilinear or ...
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How to interpolate between two MVP setups?
I am currently writing an AR experience.
I have a Camera View Matrix, A Camera Perspective matrix and the Model Matrix of the content I display.
The AR content should can be switched to "2D",...
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Deriving formula for perspective correct interpolation
I am trying to derive the formula for perspective correct texture interpolation on my own while implementing my own software rasterizer (projecting an arbitrarily rotated triangle in camera space on ...
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Methods to interpolate between 2 topologically identical 3D meshes
I have 2 3D surface meshes. These meshes have vertex-correspondence and have the same topology (same edges and triangles connecting the vertices). However, the vertex positions (3d coordinates) are ...
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Fake cubic Hermite spline interpolation with smoothstep
When scaling an image with Bicubic Interpolation, the Cubic Hermite spline interpolation is used. smoothstep is one of the four basis/blend functions of this kind ...
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Spline interpolation library in cpp
Have been searching a lot for a good spline interpolation library in cpp, came across one, which is the famous Eigen library , having the unsupported counterpart for spline fitting.<Here>.
I ...
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How to do linear interpolation?
Here in my book they have shown interpolation using parametric equation of line but I am unable to figure out how do they found out t=|y1-ys|/y1-y2 , t=|AD|/|AB| , t=|CE|/CB ,t=|EP|/|DE| here is the ...
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Determining Rational Quadratic Bezier Curve Weights for Circle
I am trying to create a spherical interpolation with 3 points. I'm currently using Quadratic Bezier Interpolation but have been told I should use Rational Quadratic Bezier Curve in order to get a ...
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How to interpolate vertices when clipping?
When we clip in homogeneous clip space, we have to generate a new vertex located at the intersection between the edge and the clip plane. We thus have to interpolate the $(x , y, z , w)$ position of ...
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How could I remove this colour interpolation artefact across a quad?
I've been reading up on a vulkan tutorial online, here: https://vulkan-tutorial.com. This question should apply to any 3D rendering API however.
In this lesson https://vulkan-tutorial.com/...
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Interpolate vertex attributes with $z$ AFTER homogeneous divide
Usually, if we want to interpolate some vertex attributes, say $A_1$, $A_2$ and $A_3$, we have to first divide them by their corresponding $z$ in view space, then we interpolate them using barycentric ...
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Perspective correct interpolation z-buffer
While I was deriving expressions for perspective-correct linear interpolation on triangles, I reached the conclusion that the interpolation may be kept linear only if view-space $Z$ is available. ...
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Interpolation in Graphics Pipeline
I am trying to program my own version of WEBGL graphics pipeline in python, however, I am confused as to where the color interpolation takes place in the pipeline. According to my research, it happens ...
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Interpolating HSV color with black
I'm interpolating RGB values by transforming them into HSV space and then back into RGB. I have trouble figuring out how to achieve ...
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Is linear interpolation in a 2D texture possible (not quadratic like bilinear interpolation)?
I am currently studying for a computer graphics exam and on the slides about bilinear interpolation it is said that it is in reality quadratic interpolation.
An (on the slides) unanswered question ...
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Irradiance field approximation with black probes
I'm posting here after some time searching the Internet and reading presentations and papers, to find out the best options to solve the problem I have.
I'm implementing irradiance field with ...
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computing derivatives of sampled data
I am trying to calculate the derivatives of a sampled data set by following an example in this book. The data is a set of 2d quads(green area in below) and their vertices(4 each). The data is in the ...
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Vertex positions from particle position
I have a question about Nvidia Flex or any particle based simulation in general:
The particles are created by sampling the mesh, which can result in fewer particles than there are vertices in the ...
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How to calculate interpolation between multiple skeleton poses?
I found out that I should use spherical linear interpolation to blend two poses of a joint. I cannot find what to do if I have hundreds of poses to blend except applying the SLERP iteratively.
What ...
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Lanczos filter implementation issue
I tried to follow Nathan Reed post Antialiasing: To Splat Or Not to implement splat method. The image I am getting thorugh the Lanczos filter is very different than Nathan. I do not understand where ...
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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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Choosing corner values for trilinear interpolation
I'm caching distances for SDF functions in volume textures for faster rendering, and I'd like to use trilinear interpolation for smoother edges. I know that I'll need distance values at each corner; ...
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ScratchAPixel : Understanding how to use Perlin's permutations hash table
Consider this course : https://www.scratchapixel.com/lessons/procedural-generation-virtual-worlds/procedural-patterns-noise-part-1/creating-simple-2D-noise . In sub-part Introducing the Concept of ...
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Why my cosine interpolation of a cube's face doesn't work?
NB please : executable use cases are available at the end of this question. I begin this question by showing you the problems of my program, then I explain how the latter works, and finally I end up ...
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Using GPU instead of CPU in Scala
I wrote a program that displays points expressed in 3D in a 2D canvas, using perspective projection. The aim is to display a cube. Each face of the cube is drawn by linearly interpolating the points ...
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How to deal with light leaks?
I'm struggling with light leaking through meshes (especially thin ones) due to interpolation between probes located on the opposite sides of those.
First approach I took was mapping all static ...
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Geometric interpretation of this bilinear interpolation equation?
Bilinear interpolation can be achieved by interpolating two values across the x axis, and then interpolating between the results across the y axis, like in the image below (from https://blog.demofox....
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How to obtain generalized barycentric coordinates for n-sided polygon?
Quadrilateral linear basis functions(generalized barycentric coordinates) are defined as:
What are the steps to calculate the above functions?
Is it possible to obtain basis functions for a 5 sided ...
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Sinc interpolation and Ideal reconstruction example
I am trying to apply sinc interpolation on this data set. The patches in the left image is a snapshot of AutoCAD 3d faces. Lux values are calculated for centre of each patch that are in 0.3m x 0.3m ...
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The mathematics of two dimensional interpolation on a quad
I am trying to wrap my head around how exactly the GPU interpolates texture coords on a quad. I realize to the GPU a quad is two triangles but I find thinking in terms of the whole quad to be easiest.
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Bilinear Interpolation
I am trying to implement bilinear interpolation as described in the paper Spatial Tranformer Networks by Jaderberg et. al (see link to paper). They describe bilinear interpolation in Equation 5 as:
$$...
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General interpolation practices
Say my animation scenario contains one mesh interpolating into another (possibly approximating over other meshes), using Bezier curves.
I know that for smooth surfaces, where normals can be ...
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Interpolating normals during animation
I'm doing linear tweening of a cyllinder to a cone of equal radius and height in OpenGL. I know parametric equations of both of them, so I derived vertex normals accordingly. Now, I know, that proper ...
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How are mipmap levels computed in Metal?
My question is specifically in regards to Metal, since I don't know if the answer would change for another API.
What I believe I understand so far is this:
A mipmapped texture has precomputed "...
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Perlin Noise with Smooth function vs Lerp
I tried implementing Perlin Noise using the Wikipedia as my main resource. From what I can tell my implementation of the ...
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What is a common approach to smooth structures in textures?
I have a screen-aligned texture resulting from multiple rendering passes. It looks about this:
I want the edges to appear smoother than they do now (but still keep their characteristic shape). When ...
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Make 3d objects from 3 projections in 3D Studio Max
In the early 3D Studio days before it got Max in its name it was possible to make a 3d object by defining its projections in xy, xz and yz plane. 3ds would then interpolate a 3d object from the ...
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Normal Interpolation for Phong shading
As the title says I have been trying to understand the normal interpolation for the Phong shading/lighting model. I am unsure of the equation to calculate the normal but I have come across this ...
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How to use Monotone cubic interpolation in 3D?
I wanted to use Monotone cubic interpolation, but the site only provide explanation for 2D case. How can I extend it to 3D?
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How do I use barycentric coordinates to interpolate vertex normal?
Given a triangle and a point inside the triangle in Cartesian coordinate system, I compute the Barycentric coordinate of the point like this:
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