# An Unsupervised Method of Change Detection in Multi-Temporal PolSAR Data Using a Test Statistic and an Improved K&I Algorithm

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## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. The Model of PolSAR Data

#### 2.2. The Proposed Method

#### Test Statistic for the Equality of Two Covariance Matrices

#### 2.3. Improved K&I

#### 2.4. The Proposed Method

#### 2.5. Evaluation Criterion

## 3. Results and Discussion

#### 3.1. Study Area and Background

#### 3.3.1. Change Detection Based on the Images from 2011, 2015, and 2016

#### 3.3.2. Change Detection Based on the 2015 and 2016 Images

## 4. Conclusions

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

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**Figure 3.**RADARSAT-2 PolSAR images acquired on (

**a**) 7 December 2011, (

**b**) 25 June 2015, and (

**c**) 6 July 2016.

**Figure 4.**Change detection maps of full frame between 2011 and 2015 based on the following: (

**a**) log-ratio (HH) and improved K&I; (

**b**) log-ratio (HV) and improved K&I; (

**c**) log-ratio (VV) and improved K&I; (

**d**) CVA and improved K&I; (

**e**) test statistic with 5% significance level; (

**f**) test statistic with 1% significance level; (

**g**) test statistic and K&I; (

**h**) test statistic and CFAR; (

**i**) test statistic and improved K&I (the proposed method).

**Figure 5.**Change detection maps of full frame between 2015 and 2016 based on the following: (

**a**) log-ratio (HH) and improved K&I; (

**b**) log-ratio (HV) and improved K&I; (

**c**) log-ratio (VV) and improved K&I; (

**d**) CVA and improved K&I; (

**e**) test statistic with 5% significance level; (

**f**) test statistic with 1% significance level; (

**g**) test statistic and K&I; (

**h**) test Statistic and CFAR; (

**i**) test statistic and improved K&I (the proposed method).

**Figure 6.**RADARSAT-2 PolSAR images of Region 1 indicated in Figure 3, acquired on (

**a**) 7 December 2011, (

**b**) 25 June 2015, and (

**c**) 6 July 2016.

**Figure 7.**CI maps and 3-D plots of Region 1 based on (

**a**) log-ratio (HH), (

**b**) CVA, and (

**c**) test statistics for the different dates of 7 December 2011 and 25 June 2015.

**Figure 8.**CI maps and 3-D plots of Region 1 based on (

**a**) log-ratio (HH), (

**b**) CVA, and (

**c**) test statistics for the different dates of 25 June 2015 and 6 July 2016.

**Figure 9.**Change detection results in Region 1 between 7 December 2011 and 25 June 2015 based on the following: (

**a**) log-ratio (HH) and improved K&I; (

**b**) log-ratio (HV) and improved K&I; (

**c**) log-ratio (VV) and improved K&I; (

**d**) CVA and improved K&I; (

**e**) test statistic with 5% significance level; (

**f**) test statistic with 1% significance level; (

**g**) test statistic and K&I; (

**h**) test statistic and CFAR; (

**i**) test statistic and improved K&I (the proposed method); (

**j**) Ground reference (white denotes the change and black denotes the non-change).

**Figure 10.**Change detection results in Region 1 between 25 June 2015 and 6 July 2016 based on the following: (

**a**) log-ratio (HH) and improved K&I; (

**b**) log-ratio (HV) and improved K&I; (

**c**) log-ratio (VV) and improved K&I; (

**d**) CVA and improved K&I; (

**e**) test statistic with 5% significance level; (

**f**) test statistic with 1% significance level; (

**g**) test statistic and K&I; (

**h**) test statistic and CFAR; (

**i**) test statistic and improved K&I (the proposed method); (

**j**) Ground reference (white denotes the change and black denotes the non-change).

**Figure 11.**RADARSAT-2 PolSAR images of Region 2 indicated in Figure 3, acquired on (

**a**) 25 June 2015 and (

**b**) 6 July 2016; (

**c**) The ground reference map (white denotes change and black denotes non-change).

**Figure 12.**CI maps and 3-D plots of Region 2 based on (

**a**) log-ratio, (

**b**) CVA, and (

**c**) test statistics at the different dates of 25 June 2015 and 6 July 2016.

**Figure 13.**Change detection results in Region 2 between 25 June 2015 and 6 July 2016 based on the following: (

**a**) log-ratio (HH) and improved K&I; (

**b**) log-ratio (HV) and improved K&I; (

**c**) log-ratio (VV) and improved K&I; (

**d**) CVA and improved K&I; (

**e**) test statistic with 5% significance level; (

**f**) test statistic with 1% significance level; (

**g**) test statistic and K&I; (

**h**) test statistic and CFAR; (

**i**) test statistic and improved K&I (the proposed method); (

**j**) Ground reference (white denotes the change and black denotes the non-change).

**Figure 14.**RADARSAT-2 PolSAR images of Region 2 indicated in Figure 3, acquired on (

**a**) 25 June 2015 and (

**b**) 6 July 2016. (

**c**) The ground-truth map (white denotes the change and black denotes the non-change).

**Figure 15.**CI maps and 3-D plots of Region 3 based on (

**a**) log-ratio, (

**b**) CVA, and (

**c**) test statistics at the different dates of 25 June 2015 and 6 July 2016.

**Figure 16.**Change detection results in Region 3 between 25 June 2015 and 6 July 2016 based on the following: (

**a**) log-ratio (HH) and improved K&I; (

**b**) log-ratio (HV) and improved K&I; (

**c**) log-ratio (VV) and improved K&I; (

**d**) CVA and improved K&I; (

**e**) test statistic with 5% significance level; (

**f**) test statistic with 1% significance level; (

**g**) test statistic and K&I; (

**h**) test statistic and CFAR; (

**i**) test statistic and improved K&I (the proposed method); (

**j**) Ground reference (white denotes the change and black denotes the non-change).

Method | FA (%) | TE (%) | OA (%) | KAPPA |
---|---|---|---|---|

HH and improved K&I | 10.49 | 11.17 | 88.83 | 0.4574 |

HV and improved K&I | 7.78 | 8.67 | 91.33 | 0.5292 |

VV and improved K&I | 8.45 | 9.31 | 90.69 | 0.5078 |

CVA and improved K&I | 0.67 | 7.41 | 92.59 | 0.0994 |

Test statistic with 5% significance level | 8.77 | 9.32 | 90.68 | 0.5204 |

Test statistic with 1% significance level | 6.9 | 7.82 | 92.18 | 0.5597 |

Test statistic and K&I | 6.16 | 7.24 | 92.76 | 0.5757 |

Test statistic and CFAR | 5.99 | 7.32 | 92.68 | 0.5626 |

Test statistic and improved K&I (the proposed method) | 5.79 | 6.98 | 93.02 | 0.5827 |

Method | FA (%) | TE (%) | OA (%) | KAPPA |
---|---|---|---|---|

HH and improved K&I | 6.55 | 7.03 | 92.96 | 0.4413 |

HV and improved K&I | 5.06 | 5.80 | 94.20 | 0.4774 |

VV and improved K&I | 5.19 | 5.67 | 94.33 | 0.5041 |

CVA and improved K&I | 1.03 | 4.73 | 95.27 | 0.0415 |

Test statistic with 5% significance level | 6.17 | 6.42 | 93.58 | 0.4857 |

Test statistic with 1% significance level | 4.59 | 5.04 | 94.96 | 0.5398 |

Test statistic and K&I | 3.96 | 4.51 | 95.49 | 0.5629 |

Test statistic and CFAR | 6.53 | 6.84 | 93.16 | 0.4630 |

Test statistic and improved K&I (the proposed method) | 2.69 | 3.51 | 96.49 | 0.6098 |

Method | FA (%) | TE (%) | OA (%) | KAPPA |
---|---|---|---|---|

HH and improved K&I | 6.69 | 7.97 | 92.03 | 0.5135 |

HV and improved K&I | 6.51 | 7.99 | 92.01 | 0.5026 |

VV and improved K&I | 6.37 | 7.50 | 92.50 | 0.5388 |

CVA and improved K&I | 1.08 | 7.36 | 92.64 | 0.0599 |

Test statistic with 5% significance level | 7.22 | 7.99 | 92.01 | 0.5358 |

Test statistic with 1% significance level | 5.37 | 6.57 | 93.43 | 0.5749 |

Test statistic and K&I | 4.86 | 6.19 | 93.81 | 0.5862 |

Test statistic and CFAR | 6.70 | 7.92 | 92.08 | 0.5179 |

Test statistic and improved K&I (the proposed method) | 3.18 | 5.09 | 94.91 | 0.6141 |

Method | FA (%) | TE (%) | OA (%) | KAPPA |
---|---|---|---|---|

HH and improved K&I | 7.15 | 7.62 | 92.38 | 0.6402 |

HV and improved K&I | 4.78 | 6.23 | 93.77 | 0.6686 |

VV and improved K&I | 6.53 | 7.15 | 92.85 | 0.6541 |

CVA and improved K&I | 0.09 | 9.35 | 90.65 | 0.0017 |

Test statistic with 5% significance level | 6.80 | 7.17 | 92.83 | 0.6593 |

Test statistic with 1% significance level | 5.30 | 6.09 | 93.91 | 0.6906 |

Test statistic and K&I | 5.64 | 5.92 | 94.08 | 0.6755 |

Test statistic and CFAR | 7.67 | 8.28 | 91.72 | 0.6130 |

Test statistic and improved K&I (the proposed method) | 3.26 | 4.81 | 95.19 | 0.7282 |

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## Share and Cite

**MDPI and ACS Style**

Zhao, J.; Yang, J.; Lu, Z.; Li, P.; Liu, W.; Yang, L.
An Unsupervised Method of Change Detection in Multi-Temporal PolSAR Data Using a Test Statistic and an Improved K&I Algorithm. *Appl. Sci.* **2017**, *7*, 1297.
https://doi.org/10.3390/app7121297

**AMA Style**

Zhao J, Yang J, Lu Z, Li P, Liu W, Yang L.
An Unsupervised Method of Change Detection in Multi-Temporal PolSAR Data Using a Test Statistic and an Improved K&I Algorithm. *Applied Sciences*. 2017; 7(12):1297.
https://doi.org/10.3390/app7121297

**Chicago/Turabian Style**

Zhao, Jinqi, Jie Yang, Zhong Lu, Pingxiang Li, Wensong Liu, and Le Yang.
2017. "An Unsupervised Method of Change Detection in Multi-Temporal PolSAR Data Using a Test Statistic and an Improved K&I Algorithm" *Applied Sciences* 7, no. 12: 1297.
https://doi.org/10.3390/app7121297