Automatic Detection of Individual Trees from VHR Satellite Images Using Scale-Space Methods

Abstract

This research investigates the use of scale-space theory to detect individual trees in orchards from very-high resolution (VHR) satellite images. Trees are characterized by blobs, for example, bell-shaped surfaces. Their modeling requires the identification of local maxima in Gaussian scale space, whereas location of the maxima in the scale direction provides information about the tree size. A two-step procedure relates the detected blobs to tree objects in the field. First, a Gaussian blob model identifies tree crowns in Gaussian scale space. Second, an improved tree crown model modifies this model in the scale direction. The procedures are tested on the following three representative cases: an area with vitellaria trees in Mali, an orchard with walnut trees in Iran, and one case with oil palm trees in Indonesia. The results show that the refined Gaussian blob model improves upon the traditional Gaussian blob model by effectively discriminating between false and correct detections and accurately identifying size and position of trees. A comparison with existing methods shows an improvement of 10–20% in true positive detections. We conclude that the presented two-step modeling procedure of tree crowns using Gaussian scale space is useful to automatically detect individual trees from VHR satellite images for at least three representative cases.

Molecular structure recognition by blob detection

“…8 In term of image processing techniques, the blob analysis has been used to identify ligands in electron density maps, 12 identify cells, 34 analyze the Leukemic blood image, 35 or detect trees from satellite images. 36 There is a great advance in the image understanding, which could be used in the analysis for molecular structures. However, molecules are much more complicated in shape and it is therefore not trivial to transplant pattern recognition and machine learning technique to recognize molecules.…”

“… 8 In term of image processing techniques, the blob analysis has been used to identify ligands in electron density maps, 12 identify cells, 34 analyze the Leukemic blood image, 35 or detect trees from satellite images. 36 …”