"Fit" in Gnuplot uses which method (Algorithm) for fitting any curve? How does it calculate the error in fitting parameters?
A rough idea about the method or the algorithm would be enough.
I am using the fit command quite often. GNUPLOT is using the least squares with the the Marquardt-Levenberg-algorithm. All available information are on this link [fit]. What they said about the error can be found here [error].
These are quite robust methods and can not be easily implemented. However, if you want have a look at the code that does the job you can find it on GitHub [code], that's the advantage with opensource :-).
Hope that helps.
Related
I am working on a new model which is very sensitive to the interpolation/fit used to describe a certain dataset. I have some success with linear splines and logarithmic fits but I think there is still significant room for improvement. My supervisor suggested I take a look at exponential splines. I have found some books on the theory of exponential spines but no reference to a library or code example to follow.
Is there a library that I am unaware of that supports this feature?
GOAL: I have to create a 3d model of a machine part. I have about 25 images of the same thing taken from different angles.
Progress: I am able to extract the coordinates for a label that is on the machine for most of the images.
Problem: but I have no idea how to proceed. I have read a bit about aero-triangulation, but I couldn't figure out how to implement it. I would really appreciate it, if you could guide me in the right direction.
It would be really helpful, if you could provide your solutions using python and opencv.
Edit: sorry but I cannot upload the code for this one as it is confidential. don't blame me please I am just an intern. Although I can tell that I cropped a template of the label from an image and then used Sift to match that template on all the images to get the coordinates of the label.
If you want to implement things yourself with OpenCV, I would command looking at SIFT (or SURF) features, RANSAC and the epipolar constraint. I believe the OpenCV cookbook describe those. Warning: math involved. And I don't know how to do dense mapping in OpenCV.
I know the GUI program "VisualSFM" that can automatically recreate 3D model from images. It uses SFM and other command line utilities behind the scenes. Since everything is opensource, you could create a python wrapper around the actual libraries (I found https://github.com/mapillary/OpenSfM asking Google). VisualSFM prints the command it calls, so a hacky way could be to call the same commands from python.
If it is a simple shape and you don't want to automate it, it could be faster to model it yourself (and the result could look better). In 1.5 week I managed to learn the basics of blender and to model a guitar necklace: https://youtu.be/BCGKsh51TNA . And I would now be able to do it in less than 1h. How long are you ready to invest to find a solution with OpenCV?
I want to plot a figure like this one:
but with only sketched data curves. The x and y axes should not be sketched.
Is this possible using Gnuplot?
I think you may find this link useful, since it's exactly what you are asking for :)
http://rfonseca.github.io/xkcd-gnuplot/
Essentially, it applies a function to jiggle the line and make it pseudo-hand-drawn:
jiggle(x) = x*(1+(2*rand(0)-0.5)*0.015)
plot jiggle(sin(x))
And this is the result:
You may also want to increase samples with set samples 1000 to have better results avoiding spikes in jiggled lines.
(As a curiosity, that page is inspired by a StackExchange answer, that contains a very advanced (and amazing, IMHO) approach to this problem, unfortunately only for Mathematica users.)
I want to compose a Predicted Interval Plots is it possible to draw the same using Tee Chart
I think is possible. I recommend you taking a look in the, Demo Examples of TeeChartFor.Net, concretely, see the example functions that you find in All Features\Functions.
Could you tell us if the TeeChartFor.Net Demo examples help you to find as you want?
I hope will helps.
Thanks,
I am new to FFT, DCT and the like. Recently I was looking into the documentation for the vDSP library from Apple and was unable to find a DCT implementation. I was wondering if anyone knows of a way to calculate the DCT using one of the FFT functions provided in vDSP?
A bit of context. I am building an image processing implementation from a graphics paper I've been reading. They mentioned using DCT after performing some image sampling.
I'd really like to take advantage of the vDSP speed if at all possible.
OK, turns out my results were off because I was using floats in stead of doubles....
So I managed to do 1D DCT on iOS on the vDSP. I'm not sure if it's the right way, but it gives me the same results as jtransform, which is good enough for me :).
And I know this question was old, but it might just help someone else searching for this.
https://gist.github.com/2140473