Hallo Elvin:
This would be a bit tricky as roads are not created equal. A paved road
and associate paint is very different from a cobblestone or gravel
road. Add shadows from trees, buildings and rock cuts and the
complexity increases. If you used a supervised classification you
would end up with clusters of pixel polygons or pixel points that would
not be very consistent. The level of work required to edit and simplify
these would be very time consuming. It is for these reasons that
original line features such as roads where digitized as simple vectors.
As bernd suggest below, existing vector data is available for most areas
and it is simply a matter of locating and accessing these sources.
Kirk
On 4/18/2019 12:10 PM, Bernd Vogelgesang wrote:
Hi Elvin,
I do not know of any trick how to extract a road network from images
besides a trained image classification model. But may the question be
allowed why you can't just use the OpenStreetMap data directly?
Cheers,
Bernd
Am 18.04.19 um 15:12 schrieb Elvin Roldan:
Hello:
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.
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.
If anybody can point me in the right direction I would appreciated.
Thanks.
Elvin Roldán
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