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I'm a new learner when it comes to QGIS.

I have a JPEG image and I want to convert it into a shapefile. The problem is when I polygonized it, the resulting image is inverted. So I decided to just digitize it manually. Now since the image I used has no coordinate reference, I assigned WGS 84. By the way I'm having difficulty assigning any geographic coordinates, so I just input WGS 84. Then I open an OpenLayers plugin which is the Bing Maps. It was just then that I realized that only raster layers can be georeferenced. So I open again my JPEG file and started georeferencing it.

When it was done the result is way off the grid. what do I have to do?

I am using QGIS 2.4 version.

  • Open layers switch project CRS (projection) into EPSG 3857 (WGS84 Web Mercator) so probably you georeferenced your image in that projection and not in WGS84. – Miro May 28 '16 at 11:39
  • So what should I do first? Do I have to georeference the image first or should I continue to digitize the image and just change the CRS of the shapefile? – jessa May 28 '16 at 12:14
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You have to georeference the raster first. Its not just about a CRS, but the extent of the raster (in CRS units) too.

You make yourselve double work if you digitize data from the raster, and then try to adjust that to reference maps like bing. There are a few tools to georeference vector data, but you will not have the convenient "pick from canvas" tool.

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