I am trying to import a historic USGS map illustrating an island in the Mississippi River from 1953. I would like to project the scanned map onto a basemap without georefrencing with control points but with the lat/long coordinates given on the map. However, I cannot seem to figure out which coordinate system to use. I have tried NAD27 and many other, but when i display it on a basemap, it ends up being somewhere in the middle of the atlantic or Caribbean. Attached is the information given on the map.
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4The text at the bottom left clearly states which coordinates are shown in the map: UTM zone 15 and something else that sounds like a 1927 Louisiana State Plane system. Regardless, you must georeference your image (if only by providing a world file), for otherwise all you are going to get are internal offsets to rows and columns in the image!– whuberCommented Mar 3, 2016 at 17:32
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1 Answer
The way I take the reference text in the bottom left is that the map features are in something called "Louisiana coordinate system, south zone" using the NAD 27 datum, which, as whuber points out, is probably Louisiana State Plane South (NAD 27 version, if there are versions).
Then it says the map has blue ticks referencing UTM 15, just for convenience. You can probably ignore that, especially since they don't appear to be labeled.
And then there are some ticks labeled with degrees, minutes, seconds, which I would guess reference NAD 27.
So, they have ticks and labels for 3 different reference systems on the map. But the labels in feet are probably what you want to georeference by, since only state plane has horizontal units in feet, of the 3 referenced systems. And state plane seems to be what the actual projection of the map features are.
That's my interpretation anyway. I'm assuming the part of the map not shown is such that the X and Y coordinates can be put together into georeferencing points.
