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I am trying to extract and georeference the orange polygons/lines from this PDF file of the city of São Paulo, in Brazil.

To do so, I am mostly trying to follow what was discussed in another question, but none of the proposed solutions are working for me.

I tried using Adobe Illustrator to extract those and export to a DXF archive, but the QGIS step is curbing my advances. I am working in EPSG 32723. My first attempt was to use the affine transformation, but the imported shapefile could not pass through: all polygons had invalid geometries.

The attempt to use JOSM also failed. I cannot process the output from downloading São Paulo's data.

Is there another path to extract those vector objects?

Vince
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catatau
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  • Why did you try JOSM? Is the data in OpenStreetMap? – Spacedman Jun 30 '22 at 18:35
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    I've loaded the PDF into Inkscape which lets me inspect the vector data under the orange areas, and its a real mess. Each orange polygon can be made of several parts, often overlapping, drawn in a very thick line, and sometimes not joining up as a polygon loop. I think it would be very difficult to extract useful vector data from this. – Spacedman Jun 30 '22 at 18:46
  • @Spacedman Thank you. I am unsure about how to use JOSM for this particular task. An alternative file from the same set is https://www.prefeitura.sp.gov.br/cidade/secretarias/upload/urbanismo/infocidade/mapas/9_distribuicao_das_favelas_2008_1.pdf – catatau Jun 30 '22 at 20:08
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    An alternative I am considering is to extract the orange polygons using Illustrator, forcing a conversion to raster, georreferencing, and then rebuilding the vectors. – catatau Jun 30 '22 at 20:14
  • Using QGIS 3.26, I could load your pdf as raster layer in the georeferencer, but not as a vector layer. – Babel Jun 30 '22 at 20:35

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