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I have used 2.18 to print maps to file (tiff) using print commposer. The base layer imported into QGIS consists of NOAA raster tiles. (My problem arises whether or not I have added other layers.) The composed maps seen in the composer look fine. However, the tiff file(s) created have problems. In particular, the tiff file output shows "sub blocks" of the image in composer moved from their original locations (e.g., scrambled).
My sense is that the problem arises from my use (misuse?) of raster tiles.

Any ideas regarding the nature of the problem and solutions/fixes?

  • Is the base layer stored on your computer, or is it coming from a web service? – csk Jun 13 '18 at 20:06
  • I've occasionally had the same issue with WMS layers. Usually it's a one-time error, and exporting the same print composer map again fixes the issue. It's also a good idea to refresh the print composer immediately before exporting. That way if your computer is have a hard time obtaining one of the tiles, you'll know before you export. Wait a bit, refresh again, and once the map displays correctly then make the export. – csk Jun 13 '18 at 20:10
  • The problem consistently arises -- every time I try. – Hamp Jun 13 '18 at 21:55
  • Also, updating preview and waiting for it to complete did not solve the problem. – Hamp Jun 14 '18 at 1:11
  • Additional information: I tried changing "parameters" to see if any such changes would result in the problem going away. I found that when I increased the scale sufficiently (e.g., going from 1:100,000 to 1:150,000) the problem did not arise. What the scale threshold was differed depending on other factors (e.g., I think map size). My guess is that the problem is related to how QGIS is dealing with the NOAA raster tiles as there are multiple images for each area which differ by the scales for the raster images. Potentialy relevant, the tiles are stored on my computer; they are not WMS. – Hamp Jun 14 '18 at 1:20

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