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PolyGeo ♦
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How to georeference a Georeferencing list of polygons in QGIS when the CRS is unknown?

I have a list of neighbourhood polygons in Casablanca, Morocco, which have an unknown CRS. Here is a link to one of the polygons: (link to a json).

I have tried several CRS in QGIS, but none of them seem to match. The origin (0,0) of the polygons appears to be located near Casablanca, which suggests that it might be a custom projection system used to render a map in some web app. screenshot of the polygons

I have also tried to find a transformation system using 3 points that I can pinpoint on the map (I identified these points from the shape of the polygons). However, I am not sure how to use them.

mapX,mapY,sourceX,sourceY,enable,dX,dY,residual
-7.66019156489551012,33.60254389161183752,13818.32712767139673815,-10907.70249749449430965,1,-0.00005545246380123,-0.00002593604340717,0.00006121808629192

-7.65505437867152239,33.59849756468478432,14799.86116917156505224,-11801.17367171987825714,1,0.00005835360482909,0.000031161882319,0.00006615289945431

-7.55462555909517963,33.57873525323550723,33560.92118483640660997,-16235.50596761874476215,1,-0.00000290114103052,-0.00000522583923868,0.00000597712431086

Can anyone suggest a method or tool to properly georeference these polygons? Any tips on how to use the identified points to determine the correct transformation system would be very helpful.

Thanks in advance for your help!

How to georeference a list of polygons in QGIS when the CRS is unknown?

I have a list of neighbourhood polygons in Casablanca, Morocco, which have an unknown CRS. Here is a link to one of the polygons: (link to a json).

I have tried several CRS in QGIS, but none of them seem to match. The origin (0,0) of the polygons appears to be located near Casablanca, which suggests that it might be a custom projection system used to render a map in some web app. screenshot of the polygons

I have also tried to find a transformation system using 3 points that I can pinpoint on the map (I identified these points from the shape of the polygons). However, I am not sure how to use them.

mapX,mapY,sourceX,sourceY,enable,dX,dY,residual
-7.66019156489551012,33.60254389161183752,13818.32712767139673815,-10907.70249749449430965,1,-0.00005545246380123,-0.00002593604340717,0.00006121808629192

-7.65505437867152239,33.59849756468478432,14799.86116917156505224,-11801.17367171987825714,1,0.00005835360482909,0.000031161882319,0.00006615289945431

-7.55462555909517963,33.57873525323550723,33560.92118483640660997,-16235.50596761874476215,1,-0.00000290114103052,-0.00000522583923868,0.00000597712431086

Can anyone suggest a method or tool to properly georeference these polygons? Any tips on how to use the identified points to determine the correct transformation system would be very helpful.

Thanks in advance for your help!

Georeferencing list of polygons in QGIS when CRS is unknown

I have a list of neighbourhood polygons in Casablanca, Morocco, which have an unknown CRS. Here is a link to one of the polygons: (link to a json).

I have tried several CRS in QGIS, but none of them seem to match. The origin (0,0) of the polygons appears to be located near Casablanca, which suggests that it might be a custom projection system used to render a map in some web app. screenshot of the polygons

I have also tried to find a transformation system using 3 points that I can pinpoint on the map (I identified these points from the shape of the polygons). However, I am not sure how to use them.

mapX,mapY,sourceX,sourceY,enable,dX,dY,residual
-7.66019156489551012,33.60254389161183752,13818.32712767139673815,-10907.70249749449430965,1,-0.00005545246380123,-0.00002593604340717,0.00006121808629192

-7.65505437867152239,33.59849756468478432,14799.86116917156505224,-11801.17367171987825714,1,0.00005835360482909,0.000031161882319,0.00006615289945431

-7.55462555909517963,33.57873525323550723,33560.92118483640660997,-16235.50596761874476215,1,-0.00000290114103052,-0.00000522583923868,0.00000597712431086

Can anyone suggest a method or tool to properly georeference these polygons?

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How to georeference a list of polygons in QGIS when the CRS is unknown?

I have a list of neighbourhood polygons in Casablanca, Morocco, which have an unknown CRS. Here is a link to one of the polygons: (link to a json).

I have tried several CRS in QGIS, but none of them seem to match. The origin (0,0) of the polygons appears to be located near Casablanca, which suggests that it might be a custom projection system used to render a map in some web app. screenshot of the polygons

I have also tried to find a transformation system using 3 points that I can pinpoint on the map (I identified these points from the shape of the polygons). However, I am not sure how to use them.

mapX,mapY,sourceX,sourceY,enable,dX,dY,residual
-7.66019156489551012,33.60254389161183752,13818.32712767139673815,-10907.70249749449430965,1,-0.00005545246380123,-0.00002593604340717,0.00006121808629192

-7.65505437867152239,33.59849756468478432,14799.86116917156505224,-11801.17367171987825714,1,0.00005835360482909,0.000031161882319,0.00006615289945431

-7.55462555909517963,33.57873525323550723,33560.92118483640660997,-16235.50596761874476215,1,-0.00000290114103052,-0.00000522583923868,0.00000597712431086

Can anyone suggest a method or tool to properly georeference these polygons? Any tips on how to use the identified points to determine the correct transformation system would be very helpful.

Thanks in advance for your help!