convert a satellite img to polygon shape file

[rashmisharma1 0]

I am having a satellite image of a city , I need to extract building network in .shp format......

how to do it.....please help

 

[deepgis 90]

Firstly, you have to classify your image using ERDAS, ENVI, Ecognition software. Secondly, convert your built-up raster class to vector (.shp format) using the mentioned software.

[rashmisharma1 0]

thanks for replying.......i have performed unsupervised classification three times with different no. of class, now i have identified the class representing the building network.... but i dont know how to convert this class to vector shapefile. kindly help.

[Lurker 2,192]

after you got the image with classes you really want, you can convert it to shp directly , I use ENVI, and this is how to do 

http://www.exelisvis.com/docs/Classification.html#ClassExport