In order to estimate the extent of rooftop area available for solar PV for domestic electricity demands, I am calculating the rooftop area of a district by extrapolating the rooftop to ground surface area ratio as calculated by randomly generated samples of clusters in Google Earth. So, I was interested if there are any pre-defined algorithm which might be more efficient for the same.
Dear Ankit,
If you are (still) using QGIS 2.x, this plugin might be usefull for you:
http://www.rasor.eu/wiki/index.php/RASOR_QGIS_plugins
Unfortunatelly, this plugin is not available for QGIS 3.x., so I have not tested it myself.
Good luck!
Cornelis
Yes Ankit, you can do that either by using ArcGIS/ArcMAP or by ERDAS
In ArcMAP, you can look into supervised image classification
and In ERDAS you can use "grow" tool
Look into the following links to get a brief idea
ERDAS: https://www.youtube.com/watch?v=HBcPB6Agr5c
ArcGIS: Look for any supervised classification video
Cornelis Stal and Harish Puppala thank-you so much, the links indeed are helpful.
Ankit,
it's probably worthwhile to be a clear about the limits of 3m data, though, especially as a function of average roof size in your study area. The smaller the buildings on average, the larger your error. Perhaps more significantly, though, is the fact that PV potential very strongly depends on the roof angle/exposure. On a flat roof you are flexible and can place PV panels at an angle (which is what I have on my own house), but if you have slanted roofs your options are limited if they are not south-oriented. Your data will not be very suitable to provide this parameter.
Best regards, Norman
I agree with Norman Kerle. 3m GSD is not enougth for that. You need a point cloud from lidar with at least 1 point/m2 or aerial photos of at least 25 cm GSD to get a point cloud or a DSM.
Article Extracting rooftops from remote sensing images using both to...
http://peterwonka.net/Publications/pdfs/2015.TGRS.Li.HigherOrderCRFRoofExtraction.pdf
You might consult these two papers too.
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