# Questions tagged [interpolation]

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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 ...
1 vote
56 views

### 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....
75 views

### 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 ...
42 views

### 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",... 106 views

### 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 ...
64 views

### 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 ...
1 vote
125 views

### 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 ...
198 views

### 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 ...
124 views

### 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 ...
231 views

### 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 ...
185 views

### 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 ...
1 vote
210 views

### 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/...
146 views

### 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 ...
696 views

### 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. ...
532 views

### 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 ...
1 vote
79 views

### 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 ...
76 views

### 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 ...
112 views

### 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 ...
333 views

### 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 ...
56 views

### 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 ...
1 vote
313 views

### 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 ...
453 views

### 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 ...
1 vote
915 views

### 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-...
111 views

### 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; ...
473 views

### 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 ...
71 views

### 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 ...
220 views

### 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 ...
472 views

### 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 ...
1 vote
750 views

### 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....
336 views

### 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 ...
239 views

### 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 ...
2k views

### 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. ...
1 vote
959 views

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### Creating a gently moving 2D fog effect

I am trying to create a fog-like effect, similar to that found using perlin noise. I know where I can find information about that effect, but it's harder for me to tell if it's an efficient route for ...
520 views

### Image rescaling algorithm

Suppose I have to use bilinear interpolation to rescale image. I more or less understand how enlargement works in case of integer scale factor. But what to do with non-integer scale and especially ...
321 views

### Find closest point on surface interpolated by 2d matrix of points

I have rectangular matrix of 3d points sampled from a parametric surface. In my program this matrix provides base points for bilinear interpolation of surface (In any (u,v) point it returns 3d point ...