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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hello:<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'>I’m writing because I’ve been a long time user QGIS and really appreciate all the work that has been put to it and all the initiatives to continue to evolve and maintain it as an important open source GIS system.<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>My question is aim does anybody know how to extract a road network using spatial analysis tools within QGIS. I want to extract all roads from aerial images to convert to vectors (polylines or polygons) to do various analysis involving the existing road network.<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>If anybody can point me in the right direction I would appreciated. <o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Thanks.<o:p></o:p></p><div id=AppleMailSignature><div><p class=MsoNormal>Elvin Roldán<o:p></o:p></p></div></div></div></div></body></html>