Efficient Framework for Palm Tree Detection in UAV Images

The latest developments in unmanned aerial vehicles (UAVs) and associated sensing systems make these platforms increasingly attractive to the remote sensing community. The large amount of spatial details contained in these images opens the door for advanced monitoring applications. In this paper, we use this cost-effective and attractive technology for the automatic detection of palm trees. Given a UAV image acquired over a palm farm, first we extract a set of keypoints using the Scale-invariant Feature Transform (SIFT). Then, we analyze these keypoints with an extreme learning machine (ELM) classifier a priori trained on a set of palm and no-palm keypoints. As output, the ELM classifier will mark each detected palm tree by several keypoints. Then, in order to capture the shape of each tree, we propose to merge these keypoints with an active contour method based on level sets (LSs). Finally, we further analyze the texture of the regions obtained by LS with local binary patterns (LBPs) to distinguish palm trees from other vegetations. Experimental results obtained on UAV images with 3.5 cm of spatial resolution and acquired over two different farms confirm the promising capabilities of the proposed framework.