CODEWITHSUNDEEP
image-processingopencvgaussian
Poul K. Sørensen
Poul K. Sørensen

Reputation: 17560

How to do a Gaussian filtering in 3D

How do i do a gaussi smoothing in the 3th dimension?

I have this detection pyramid, votes accumulated at four scales. Objects are found at each peak.

Detection Pyramid

I already smoothed each of them in 2d, and reading in my papers that i need to filter the third dimension with a \sigma = 1, which i havent tried before, i am not even sure what it means.

I Figured out how to do it in Matlab, and need something simular in opencv/c++.

Matlab Raw Values: Raw Matlab Smoothen with M0 = smooth3(M0,'gaussian'); : Smooth

Upvotes: 9

Views: 10421

Answers (2)

Yoav
Yoav

Reputation: 6098

Gaussian filters are separable. You apply 1D filter at each dimension as follows:

for (dim = 0; dim < D; dim++)
    tensor = gaussian_filter(tensor, dim);

I would recommend OpenCV for an implementation of a gaussian filter (and image processing in general) in C++.

Note that this assumes that your pyramid levels are all of the same size. You can have your own functions that sample your scale-space pyramid on the fly while convolving the third dimension, but if you have enough memory I believe that it would be faster to scale up your coarser level to have the same size of the finest level.

Upvotes: 3

Viktor Latypov
Viktor Latypov

Reputation: 14467

Long ago (in 2008-2009) I have developed a small C++ template lib to apply some simple transformations and convolution filters. The library's source can be found in the Linderdaum Engine - it has nothing to do with the rest of the engine and does not use any of the engine's features. The license is MIT, so do whatever you want with it.

Take a look into the Linderdaum's source code (http://www.linderdaum.com) at Src/Linderdaum/Images/VolumeLib.*

The function to prepare the kernel is PrepareGaussianFilter() and MakeScalarVolumeConvolution() applies the filter. It is easy to adapt the library for the different data sources because the I/O is implemented using callback functions.

Upvotes: 2

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