Category Archives: Research

Compute the kurtosis of standard Gaussian distribution

In this post, we will derive the kurtosis of stand Gaussian distribution

kurtosis0

is 3. We use the following equation to calculate the fourth central moment

Image

The fourth central moment is

kurtosis2

Therefore, the kurtosis is

Image

For an application of Kurtosis analysis in saliency detection/in-focus segmentation, please refer to our paper and source code.

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Vision的project

vision的最后一个project做的是marc pollefyes的polar rectification. 做的时候比一开始想象的要稍微复杂一些,花了挺长时间的,但效果还是挺好的。

LEGO® MINDSTORMS® NXT

http://shop.lego.com/product/?p=8527&LangId=2057&ShipTo=US

以前见到过Lego这个名字,但没有在意过。今天神奇的发现别人做的vision的作业是在lego robot上做得。他们自己搭了个lego robot,然后在这个robot装载了两个web camera。然后自己写code,通过stereo image来计算depth map提供给这个robot做导航信息,效果还是很神奇的。这一个vision的project应该是融合了AI、Vision等学科,很有意思。所以说,老美也不只是会玩,玩也能玩出奇特的东西。

RANSAC简单实用

最近经常看到RANSAC的字眼。最先是在使用dynamic silouette作multi-camera calibration的paper里看到的,他们使用改进的RANSAC算法来估计Epipolar Geometry的参数;后来又在vision的课上看到了RANSAC,用来做从两副图像生成paranoma image,后来看到RANSAC主要被用来估计fundamental matrix的7个参数;再后来就在各式各样的matlab工具箱里看到RANSAC。总之一句话,RANSAC是个很简单的但很有效的算法,以后要经常使用些。

“We approached the fitting problem in the opposite way from most previous techniques. Instead of averaging all the measurements and then trying to throw out bad ones, we used the smallest number of measurements to compute a model’s unknown parameters and then evaluated the instantiated model by counting the number of consistent samples.

—- RANSAC: An Historical Perspective, Bob Bolles & Marty Fischler

一个用RANSAC估计Homography的算法为: