Detecting Invasive Plants Using Hyperspectral and High Resolution Satellite Images

The rapid spread of nonnative plant species have caused considerable negative impact to the biodiversity and ecosystems in Taiwan. To better unders tand the status and to suppor t researchers and decision makers to develop strategies and remedies for this problem, it is necessary to obtain accurate spatial information and the progression about the invasions of foreign species into native ecocommu nity. The availability of hyperspectral and high resolution satellite data provides researchers an opportuni ty to pursue more complex analysis and have a great potential to achieve better performance and results in an invasive plants investigation. High resolution images provide detail spatial information about the target areas but are often limited to single or few spectral bands. On the other hand, hyperspect ral data consist of tens to hundreds of contiguous bands but lack of spatial details. Therefore, a combination of both types of data is likely to be an optimal approach to the mapping of alien plants. However, with the large data volume and high data dimensionality, the major challenge of using hyperspectral and high resolution data together is to extract useful information effectively and efficiently. This paper presents a work in progress of developing a systematic method to use hyperspectral and high resolution satellite images to identify an invasive plant (horse tamarind, Leucaena Leucocephala ) that is spreading in an alarming rate in southern Taiwan. The developed method first locates "areas of interest" where target species is likely to populate most densely. Then a twolevel analysis procedure is implemented using hyperspectral and high resolution satellite images to identify and map the distribution of target species. The first phase of the procedure is to analyze hyperspectral images with selected (helpful) features to obtain a preliminary result. The second phase is to isolate the areas where discrimination of target plant species is not satisfactory and to improve the accuracy of discrimination with the analysis of canopy structures in high resolution satellite images. Verification with ground truth samples indicates that the developed method of combining high resolution and hyperspectral images analysis is an effective and efficient approach to detect invasive plants in a large area.