[Qgis-user] Road Network Extraction out of Raster Images

[Bernd Vogelgesang]

Hi Elvin,

would be nice then to read here one day about your findings.

Cheers,

Bernd

Am 20.04.19 um 18:02 schrieb Elvin Roldan:
> Hell again:
>
> Thanks for the help I followed youre recommendations and use base
> layer for openstreet map and edited for my needs. None the less I will
> keep trying to develop this in spatial analysis due that Im working
> with drone collected data and a lot of areas (whole municipalities) to
> develop infrastructure maps.
>
> I will keep posted on progress. Thanks for the help.
>
> Elvin Roldán
>
> On Apr 18, 2019, at 12:04 PM, Kirk Schmidt <kirk at nortekresources.com
> <mailto:kirk at nortekresources.com>> wrote:
>
>> 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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>> --
>> Kirk Schmidt, MScF, BScF, RPF
>> General Manager
>> Nortek Resource Solutions Inc.
>> RR # 1
>> Thorburn, NS
>> B0K 1W0
>> Tel (902) 922.3607
>> Email:kirk at nortekresources.com
>> Web:www.nortekresources.com
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