Detecting Vehicles from Satellite Images Presented By: Dr. Fernando Rios Dr. Rocio Alba Flores Sumalatha Kuthadi Prashant Jain

Image Segmentation Segmentation is distinguishing the objects from the background i.e. identifying objects in an image. For intensity images, segmentation can be done in four ways: – Threshold Techniques – Edge Based Techniques – Region Based Techniques – Connectivity-Preserving Relaxation Method

Threshold Techniques In intensity images, vehicles are either white or black i.e. vehicles have intensities in contrast with the background. White vehicles have the maximum intensities and black vehicles have the minimum intensities of the image. Intensity threshold depends on the intensity of the vehicles. Different thresholds are required to identify white and black vehicles. To identify white vehicles, consider the maximum intensities of the image. To identify black vehicles, consider the minimum intensities of the image. Convert the intensity image to binary image using these thresholds. Black and white cars will get turned into white patches and the background turns into black in binary image. Now, we can count the vehicles using any Clustering algorithms.

Identifying White Vehicles To identify white vehicles, we have taken three different thresholds because -: – Many factors, like weather, sunlight, road dividers etc effect the intensities of an image. – Vehicles may have different intensities in different images and also in the same image. – Some vehicles may have large intensities like 230 and some may have intensities like 170 in the same image.

Identifying White Vehicles (contd)  To get better results, we considered three different thresholds. They are: Mean of the maximum intensities that is obtained from each row of the image. Minimum intensity of the maximum intensities. Average of above two values.

Identifying White Vehicles (contd) By using three thresholds, three binary images are obtained. Objects that are common in any two images are counted as vehicles.

Identifying Black Vehicles Black vehicles usually have intensities lesser than 40. If intensity goes beyond 40, we get a gray shade. Only one threshold is considered for black vehicles which is the mean of the minimum intensities of each row of the image.