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I have a government-sourced geotiff which I have imported into ArcMap 10.4 as a raster basemap. In a TIFF viewer it displays correctly but in ArcMap it appears vertically squashed by roughly 20%.

The data frame coordinate system is GCS_WGS_1984 WKID: 4326. And here is some data provided to me along with the tiff file:

Panel Limits: Lat -34 5 55.812 to -33 23 59.347 Lon 151 7 58.170 to 151 39 42.778

Referencing:       Geographic Lat/Long
Spheroid:          WGS84
Horizontal Datum:  WGS 84
Scale:             1:75000

Image Size:        7258 cols x 10867 rows
Image Resolution:  254 dots-per-inch
Number of Colours: 27

TIFF Version #:    42
GeoTIFF Version #: 1
TIFF Compression:  Packbits

Why does it appear squashed, and how can I fix it?

I found this but it did not seem to help: https://geonet.esri.com/thread/34535. Unable to independently verify the geotiff is WGS84. I am running Windows 10 Pro under Parallels on a MacBook Pro.

What is stranger, I also have a KML map of the same area and when I alternate between the two maps in ArcMap, by disabling one of them, I can see that they are exactly coincident. In other words, both are squashed, by the same amount.

The only thought I had was that one degree of longitude, in metres, varies with the cosine of the latitude, and coincidentally 1 - cos (33.5) is about 20%. Could that have something to do with it? Clutching at straws here.

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    varies with the cosine of the latitude - Bingo! The TIFF viewer isn't taking latitude into account when showing you the image. – Mintx Jun 28 '16 at 15:54
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    @Mintx: In the TIFF viewer, the map is in the correct proportions. When a Google map of the same area is overlaid, it matches on-the-ground features almost exactly. When a precise circle is overlaid on a circular compass rose on the map, that matches almost exactly also. So the TIFF viewer would appear to be doing the right thing. The problem must lie elsewhere. I presume I am right in expecting ArcMap to display the map without squashing it. – BillF Jun 30 '16 at 0:42
  • @Mintx Also, I can confirm that the degree of squashing is precisely equal to the cosine of the latitude. – BillF Jun 30 '16 at 0:45
  • Further information: In ArcMap, features are displayed with the correct latitude and longitude. – BillF Jun 30 '16 at 0:47
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Why does it appear squashed? In the TIFF viewer, the map is in the correct proportions. When a Google map of the same area is overlaid, it matches on-the-ground features almost exactly.

Google Maps uses a spherical Mercator projection of WGS84 lat/longs, called WGS84 Web Mercator. Earth is not a sphere, so the Web Mercator projection stretches as a function of latitude.

When you bring the image into ArcMap, it uses the WGS84 geographic projection as stated in your data frame CRS.

Try changing your data frame to Projected Coordinate Systems -> World -> WGS84 Web Mercator (auxiliary sphere)

enter image description here

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