Dear Harsha,

first the png image should be georeferenced and saved as raster file (e.g. geoTiff). Then you can vectorize the raster and dissolve the similar cells to polygons. If the color/cell value of the highlighted area is heterogeneous, then some raster calculations and/or classification are needed before vectorization.

I suggest using QGIS for georeferencing and R for all the other steps.

HTH,

Ákos

Hey there Akos.

Thank you for answering. I would like to mention some details.

This is the map : https://siga.jakarta.go.id/peta/palyja#

I want the blue lines extracted as polygons, I checked the network tab and it seems everything is being pulled off from open street maps.

Does your previous answer still stand?

You mean the blue dashed lines? What exactly are these? Trajectories of ships? You need to be more specific.

Dear Harsha,

if this is from OpenStreetMap, why not downloading the data as points/lines/polygons that are freely available from download.geofabrik.de?

Oh, it is easier... The blue, linear polygons that are overlaid on the streets of Jakarta are available here: https://siga.jakarta.go.id/uploads/file_shp/palyja.zip

Download it, unzip it, and you can open in QGIS/ArcMap as it is a simple polygon-type shapefile.

Hello everyone. I apologize for my unclear question. It is indeed my first time with maps and I didn't know what information was essential. Also, thank you very much Akos for your time and help.