Problem using polygonize / raster to vector in QGIS

Question

I want to take my raster (multi ortophotos (.tiff) placed together using the "Build virtual Raster" option with the pyramids) and poligonize it. Something like this: gdal polygonize in python error, blank polygon created into an .shp file.

However, when I use the poligonize option an error appears saying that the process finished shortly after the beginning.

After having a closer look on my raster I found this: enter image description here

Could this be the problem? How can I take them out of my layer?

After some research, I found the clip plugin but to use these I have to have a shapefile with the contour or something like that and I don’t have nothing. I must say I’m a new to QGIS and so to Geography :)

I thought about making my own contour, by drawing the boundaries, but could not found any plugin to do this. Is there a way to clean up my layer in order to pass it from raster to vector correctly? in shapefile so that I can open it, for example, in AutoCAD?

Answer 1

Thank you very much for your help.

I was trying to use SERVAL but I couldn't find any example of application. What I managed to do in order to make the black patches to dissapear was this:enter image description here

Not sure if this was what you were suggestion. I tried to use the poligonized with these layer but the error message was the same.

• Kazuhito: It seems you have been successful in using the plugin, provided the cell value for the black background here is same as the white background in the original image. Then probably the cause of the error is not those patched area.
• Kazuhito: You can edit your original post to reflect that the black patches are now excluded from the suspect list, which will make this issue more focused on its cause. I have dropped my comment on Serval plugin.
• Rodri: @Kazuhito, could you provide a link to download your last raster so I can try to do it myself?
• Kazuhito: @Rodri Sorry I am not the owner of this post; I do agree that it would help if OP can provide even a part of the raster.