segment region of interest

i wanted to segment roads from satellite images.... for that i filtered the image using "derivative of Gaussian".... the code i used is from the link below....

http://www.mathworks.in/matlabcentral/answers/57077

and then tried otsu's method for segmenting the road regions only.... but other portions of the image is also coming.... can someone help me to segment the road regions only from the image....

this is the image i'm working...

http://img824.imageshack.us/img824/9913/ds1o.jpg

http://img515.imageshack.us/img515/7272/ds2ux.jpg

please can someone help me to segment only the roads from the images... please do reply......

Answer 1

[Image Analyst]

This is not easy in general, especially with parking lots in the image. We can't develop what will have to be a sophisticated algorithm for you and can only refer you to papers that have sucessfully done this already: http://iris.usc.edu/Vision-Notes/bibliography/contentscartog.html#Cartography,%20Aerial%20Images,%20Remote%20Sensing,%20Buildings,%20Roads,%20Terrain,%20ATR See these sections

22.2 Road Network Detection, Road Extraction Systems  
    22.2.1 Road Following, Road Tracking Systems, Connecting Fragments, Extracting Fragments
    22.2.2 Road Network Model Integration, Updating, and Change Detection
    22.2.3 Road Extraction in Radar, SAR, Lidar, Laser, Depth