Identifying tree species from google earth imagery: Detection of Palmyra trees in northern Sri Lanka

摘要

A manual census of trees over a large geographic area can be very costly. Therefore, remote sensing is a powerful tool for the task. In this regard, this research focuses on the Google Earth image-based detection and counting of Palmyra trees in the northern part of Sri Lanka. Freely accessible Google Earth images are for the first time used here for the detection of specific tree type. Color information is used to identify their foliage. As the color information itself can be ambiguous at times, a complimentary analysis in the form of the identification of shadows is also carried out. Here, the fact that these tall trees throw a considerable shadow on the ground or other lower lying features is exploited. Phase Stretch Transform is used to identify the shadows. The detection results in successfully extracted Palmyra among other vegetation in Google Earth images and shows with a precision of 92.6% and recall of 88%.