以多時期與PCA+NDVI法改善地物分類之正確性與完整性

Using Multi-temporal and PCA+NDVI to Improve the Accuracy and Integrity of Land Cover Classification

張國楨(Kuo-chen Chang) ； 田應平(Ying-Ping Tian) ； 施孝謙(Hsiao-Chien Shih)

《地理研究》 57期 (2012/11) Pp. 49-60

https://doi.org/10.6234/JGR.2012.57.03

摘要

Satellite image analysis is one of the main methods of monitoring of environmental changes. The accuracy and credibility of the results depend on the spectral resolution of the imagery used and the spectral separability between features being monitored. If original imagery from single period is used to perform classification, the results are often affected by the noise of imagery itself and spectral similarity between different features. In this research, we proposed an improved solution for change detection that combines a Principle Component Analysis (PCA) process to remove noise and a multi-temporal process to increase spectral resolution. The study area is located on Shezi Island with imageries from 2005, 2006, 2007. The original imageries were processed with PCA to retain the first two major components which account for over 95% of total explanation. The resulting imageries were inversed by IPCA process back to 4 bands imageries. NDVI was calculated for each time period and stacked with IPCA imageries to create a new multi-temporal imagery for further unsupervised classification. The experimental results showed that the PCA process does enhance the spectral characteristic of features being monitored. An unsupervised classification process was applied to the multi-temporal imagery. The result was compared to that from 2007 and showed a significant improvement in both accuracy and completeness of the land cover classification.

關鍵字

地物分類 ； 多時期影像 ； PCA ； 非監督式分類 ； 完整性

並列摘要

Satellite image analysis is one of the main methods of monitoring of environmental changes. The accuracy and credibility of the results depend on the spectral resolution of the imagery used and the spectral separability between features being monitored. If original imagery from single period is used to perform classification, the results are often affected by the noise of imagery itself and spectral similarity between different features. In this research, we proposed an improved solution for change detection that combines a Principle Component Analysis (PCA) process to remove noise and a multi-temporal process to increase spectral resolution. The study area is located on Shezi Island with imageries from 2005, 2006, 2007. The original imageries were processed with PCA to retain the first two major components which account for over 95% of total explanation. The resulting imageries were inversed by IPCA process back to 4 bands imageries. NDVI was calculated for each time period and stacked with IPCA imageries to create a new multi-temporal imagery for further unsupervised classification. The experimental results showed that the PCA process does enhance the spectral characteristic of features being monitored. An unsupervised classification process was applied to the multi-temporal imagery. The result was compared to that from 2007 and showed a significant improvement in both accuracy and completeness of the land cover classification.

並列關鍵字

Land Cover Classification ； Multi-temporal Imagery ； PCA ； Unsupervised Classification ； Completeness

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