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QGIS 3.10, Ubuntu 18.04

I was questioning why my map displayed at a +10 degree rotation, but displayed unrotated in the Print Layout.

What I do now:

  1. Set Project->Properties->CRS to EPSG:5070 - NAD83 (Conus Albers)

  2. Load 8 NED30m tiles covering the Grand Canyon.

  3. Create a Virtual Raster from those and reloaded the .vrt file.

    3.1 Change the newly reloaded VRT Layer's CRS to EPSG:5070

    3.2 Zoom to that layer--to verify that it is indeed not rotated.

  4. Export the zoomed layer as a Geopkg in EPSG:5070.

  5. Exit QGIS.

  6. Restart QGIS, set Project->Properties->CRS to EPSG:5070.

  7. Load the EPSG:5070-saved Geopkg as a new raster layer.

  8. Verify that its Layer CRS is EPSG:5070.

  9. Expect the layer to display with North UP, which it does, with the addition of steps 3.n and the edition of step 4.

  10. The layer also displays properly in Print Layout.

Harking back Importing USGS ned30m (NAD83) into Project (NAD83/Conus Albers, OTF on): coords still Lat/Long, Project->ProjectProperties->General->CoordDisplay IS set to "MapUnits" as directed by @AndreJ there.

Could someone explain why this is happening, and perhaps suggest another approach, or PCS, to reach my goal; namely, a large-format print of multi-tile b&w elevations?

The corrected steps result in a GCS layer exported to PCS to display squarely/rectilinearly in a PCS project.

Screenshot showing rotation of layer saved-as/reloaded-as PCS CRS

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1 Answer 1

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The "tilt" may be normal, depending on the coordinate reference system chosen for the projection, and how far from the center one looks.

All projections distort, and in fact, different projections are created to minimize distortion in the area of interest (while distorting areas further away more severely) or by spreading the distortion evenly over the entire area.

My map has 8 tiles spanning 2x8 degrees and when viewed in their entirety, in the projection I had chosen, there is clear curvature along lines of latitude. The tiles on the ends are "tilted" compared to the ones in the middle. My bad luck was to pick one of those end tiles and mistake the tilt for some kind of misprocessing.

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