Questions tagged [interpolation]
The interpolation tag has no usage guidance.
41
questions
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0answers
87 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 ...
2
votes
1answer
104 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 ...
2
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0answers
44 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
2answers
100 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 ...
0
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0answers
192 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
1answer
161 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-...
0
votes
1answer
66 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; ...
2
votes
2answers
202 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 ...
3
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0answers
65 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 ...
2
votes
0answers
175 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 ...
3
votes
1answer
214 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
2answers
546 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....
3
votes
1answer
181 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 ...
3
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0answers
156 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 ...
5
votes
1answer
727 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
1answer
538 views
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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0answers
60 views
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 ...
2
votes
0answers
61 views
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 ...
14
votes
1answer
2k views
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 "...
1
vote
1answer
463 views
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 ...
2
votes
1answer
154 views
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 ...
2
votes
0answers
31 views
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 ...
5
votes
1answer
1k views
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 ...
3
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1answer
239 views
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?
5
votes
2answers
3k views
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:
...
4
votes
1answer
553 views
Screen coordinates, barycentric coordinates and global coordinateas
To continue with this my other question, here's the problem. So, I've a slide, which I'm trying to understand.
Here are my questions.
What are the barycentric coordinates of? From my previous ...
5
votes
1answer
185 views
How to rasterize a line when the background color is not always white?
I've to rasterize a line taking into account not only the background color of the screen, which is white, but also the color of other objects in the scene. In my case, I've just another object, a ...
3
votes
3answers
75 views
Does the blending matrix change between calculating various curve segments in a uniform cubic B-splines approximation?
I would like to ask about uniform (periodic) cubic B-splines (approximation, no interpolation).
$$B=1/6\begin{bmatrix}-1&3&-3&1\\3&-6&3&0\\-3&0&3&0\\1&4&1&...
3
votes
1answer
303 views
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 ...
6
votes
1answer
398 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 ...
3
votes
1answer
269 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 ...
5
votes
1answer
375 views
How can you interpolate over an array of say 5 colors?
I have an array of color values. I have an interpolating parameter, t, which varies from 0 to ...
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vote
0answers
218 views
How to do keyframe interpolation on matlab?
I want to do keyframe interpolation in matlab.
If I understand correctly, it uses splines to approximate the the motion of specific pixel points within the frames(through transforms). Correct me if I'...
8
votes
2answers
2k views
What is bilateral upsampling?
I've worked with various interpolation algorithms including linear, cubic (and bilinear and bicubic), other bezier (and nurbs, etc) based interpolations, lagrange interpolation and some others, but I ...
6
votes
1answer
445 views
Perspective correct interpolation of normal values
I'm currently writing a software rasterizer and I'm at the point where I can draw arbitrary triangles with vertex colors and perspective correct texture mapping. I do point and directional lighting by ...
4
votes
1answer
1k views
Is there a way to interpolate color across the line with only integer calculation ?`
Here is my function that does interpolation
...
4
votes
2answers
822 views
Linear interpolation on Plane (Marching Cubes)
Let's assume I have the following cube.
Let's assume the isovalue = 0. I would like to draw the resulting triangles of the isosurface.
I know that first I define which values are inside or outside ...
4
votes
0answers
907 views
Which interpolation algorithm does MS Paint on Windows 7 use for image rescaling?
I was about to scale this image down to 64x64 pixels:
The result I got on MS Paint on Windows 7 was surprisingly good (i.e. crisp edges):
, whereas scaling it with GIMP resulted in for cubic and ...
4
votes
1answer
791 views
Interpolating vectors on a grid
If you have values on a grid and you want to find the value of a point within one of the cells, you can use techniques like bilinear or bicubic interpolation to get the data at that point.
What ...
4
votes
0answers
62 views
MRF and Textures
I am pursuing my research in Texture Interpolation. After digging deep into it, I'm stuck at a point. It is proven that textures can be modeled as Markov Random Fields and that each texture can be ...
11
votes
1answer
444 views
Is a cubic Lagrange interpolation tensor product the same as bicubic interpolation?
I just implemented some interpolated texture sampling by sampling the 4x4 nearest pixels then doing Lagrange interpolation across the x axis to get four values to use Lagrange interpolation on across ...
