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I'm attempting to make a seamless raster from US Topo Maps for a large portion of the Western US. I have succeeded in converting the GeoPDFs from The National Map into GeoTIFF format using gdal_translate, but when I attempt to process them further I receive a warning related to the rotation of the rasters.

#R 3.5.0 x86_64-w64-mingw32

library(raster) #version 2.6-7

iraster <- raster(i)

Warning message:
In .rasterFromGDAL(x, band = band, objecttype, ...) : 

 This file has a rotation
 Support for such files is limited and results of data processing might be wrong.
 Proceed with caution & consider using the "rectify" function

When I attempt to rectify the rasters, per the suggestion of the warning from the raster function, I am unable do so because I receive the following error:

iraster.rectified <- rectify(x = iraster)

Error in validityMethod(object) : invalid extent: ymin >= ymax

I noticed that the res.y attribute of the raster is negative, so I'm wondering if that could have something to do with my issue.

Here is the geotransformation info from iraster:

iraster@rotation@geotrans
         ll.x         res.x     oblique.x          <NA>     oblique.y          res.y 
 3.762988e+05  1.015902e+00  1.396716e-02  4.097299e+06  1.396716e-02  -1.015902e+00
  • the y resolution is always -ve, it allows for graphic images having their origin in the top left while geography uses bottom left. – Ian Turton Jun 14 '18 at 19:25
  • OK, but that doesn't address the issue that I'm having, which is that I can't rectify or otherwise process the raster. – hydrogeodude Jun 14 '18 at 20:18

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