2

I used Georeferencer to georeference a jpg map and saved as tif. I used Thin Plate Spline, Cubic Spline, and LZW as settings. The tif shows fine in OSX Preview. gdalinfo reports

Driver: GTiff/GeoTIFF
Files: LosAngelesCentral1917.4326.QMS.tif
       LosAngelesCentral1917.4326.QMS.tif.aux.xml
Size is 1301, 1781
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]
Origin = (-13168892.384256949648261,4041852.682744845282286)
Pixel Size = (8.488964512573681,-8.488964512573681)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  COMPRESSION=LZW
  INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left  (-13168892.384, 4041852.683) (Invalid angle,Invalid angle)
Lower Left  (-13168892.384, 4026733.837) (Invalid angle,Invalid angle)
Upper Right (-13157848.241, 4041852.683) (Invalid angle,Invalid angle)
Lower Right (-13157848.241, 4026733.837) (Invalid angle,Invalid angle)
Center      (-13163370.313, 4034293.260) (Invalid angle,Invalid angle)
Band 1 Block=1301x2 Type=Byte, ColorInterp=Red
  NoData Value=0
Band 2 Block=1301x2 Type=Byte, ColorInterp=Green
  NoData Value=0
Band 3 Block=1301x2 Type=Byte, ColorInterp=Blue
  NoData Value=0

The QMS in the name refers to QuickMapServices which I was using as a reference instead of OpenLayers. I was using the Mapquest OSM map. I can look at properties in QGIS. I can Zoom To Layer and nothing happens—meaning if I shift the map away from where it should appear, the QGIS map doesn't move.

Where should I look for fixes?

QGIS 2.12.1 Lyon OSX.

  • I reran gdalinfo without the LosAngelesCentral1917.4326.QMS.tif.aux.xml file present and got the same results (of course without that file showing). BTW what system are these coordinates being reported in. -13168892.384, for example. Thank you. – Greg Feb 28 '16 at 17:53
2

You have set the raster CRS to WGS84, but used coordinates from a tile service which might use EPSG:3857.

So you have to set the CRS of the raster to the same CRS to get it working.

Raster -> Projections -> Assign projection should do the trick.

BTW the corner coordinates are still in EPSG:3857, around the center of Los Angeles:

enter image description here

  • That's it. Thank you. I thought the wrong CRS would just put it in the wrong place. – Greg Feb 29 '16 at 15:27
  • And you could tell because of the units of the map coordinates? Is EPSG:3857 common for web maps? – Greg Feb 29 '16 at 15:47
  • All Google-like tile services (bing, Openstreetmap etc) use EPSG:3857. I added the coordinates as delimited text in QGIS, and added an OSM background to proof it. QGIS could not display your file, because it expected degrees, and the coordinates were far to great for that. Gdalinfo noted several invalid angle for the same reason. – AndreJ Feb 29 '16 at 16:15
0

Your answer and some more Googling have started to bring these pieces in focus. Nothing I looked at clearly stated what the units are. Meters relative to something. But accuracy to micrometers implied. Oh well. Thanks again. I can see my map and it lines up with my data.

  • The Google Mercator projection uses "meters", but they are only true meters at the equator, and stretched away from it. – AndreJ Mar 2 '16 at 6:35

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