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I have a couple of historical maps of Africa which need to be georeferenced. There are latitude and longitude information on the map and now my question is may I use wgs84 in order to georeference these maps or there is some other coordinate system better for this?

The work is in ArcGIS 10.4, so I have used wgs84 control points and after that connected with each point from raster. There are some bad results in raster position so I want to increase the accuracy on some way.

The map is annotated with Streit 1929.

The scale of the original maps are 1:10000000, with Africa broken up onto 5 pages. Pictures of the maps are here.

The map scales are listed here.

  • If the maps are small scale (whole continent), it is unlikely to matter which GeoCRS you use for georeferencing. The maps just aren't accurate enough for it to matter. Ah, pictures of the maps here: atlassen.info/atlassen/flemming/hiera02/hiera02p.html#afrika – mkennedy Aug 21 '18 at 20:35
  • A note states that the cartography was from another atlas, done by Flemming. There the Africa map says equal area azimuthal projection, centered at lat=0, lon=15E. – mkennedy Aug 21 '18 at 20:47
  • Great. So, what is your suggestion, should I just use wgs84 points and connect it with grid intersections, or I can increase the accuracy maybe with more points on rivers, roads intersetions, etc...? – user122678 Aug 21 '18 at 20:54
  • I would try georeferencing to a custom Lambert azimuthal equal area with lat=0, lon=15E. For the datum/geoCRS, try wgs84. Based on European publication at turn of 20th century, could try Bessel 1841 as an alternative. – mkennedy Aug 21 '18 at 21:11
  • I will definitely try this, but how to define these parameters in ArcGIS. Could you give me some instructions about that. – user122678 Aug 21 '18 at 21:16
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If the maps are small scale (whole continent), it is unlikely to matter which GeoCRS you use for georeferencing. The maps just aren't accurate enough for it to matter. Pictures of the maps are here.

The scale of the original maps are 1:10000000, with Africa broken up onto 5 pages.

The map scales are listed here.

A note states that the cartography was from another atlas, in the Sohr-Berghaus Handatlas in 1909. There the Africa map says equal area azimuthal projection, centered at lat=0, lon=15E.

I would try georeferencing to a custom Lambert azimuthal equal area with lat=0, lon=15E. For the datum/geoCRS, try WGS84. Based on European publication at turn of 20th century, you could try Bessel 1841 as an alternative.

More details. Use the Grids and Graticules tool to build a graticule with the proper spacing in latitude/longitude. Assign it the WGS84 geographic coordinate system with the Define Projection Tool. Use the Project Tool to create a new feature class with a custom Lambert azimuthal equal-area projection.

You'll have to create a custom projected coordinate system:

GeoCRS: WGS 1984 (EPSG::4326) Projection: Lambert azimuthal equal area central meridian/longitude of origin: 15E Latitude of origin/center: 0.0

Other parameters can be left set to zeroes.

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Are there enough landmarks on the map that are still visible on Google Earth (for example bridges or crossroads)? If so, you could try this method with MAPC2MAPC. You don't need to pay/register to do this and it will create an OZI .MAP file, a JPR, World file etc.

http://www.the-thorns.org.uk/mapping/GEcalibrate.pdf

  • Interesting, but there is a very low number of existing objects from that time. – user122678 Aug 21 '18 at 12:51
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The 84 part of wgs84 refer to the year 1984 (wgs84 = World Geodetic System 1984) at which it was determined. So if your maps are older than 1984 you are sure that this system is not usable for it. (and as a side note wgs84 is not a projection but your map are projected...)

You should check if there is any indication on the maps other than lat/lon that could help you to determine their actual crs, if you know who made the maps and when, you may be able to find the usual projection for the area at the time....

  • Unfortunately there is no other information about maps except the lat/long. I alsi know the maps are from year 1928. – user122678 Aug 21 '18 at 12:11
  • And also this mark: "Streit_1929" – user122678 Aug 21 '18 at 12:24
  • So your map are probably from ''Atlas Hierarchicus, Karl Streit (1929)'' (books.google.fr/books/about/…). You should probably ask another question about the projection used on this book for the African sheet. (sorry can't help you more) – J.R Aug 21 '18 at 12:38

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