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Need help figuring out 1700s map projection

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#1
David Medeiros

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Hi all,

 

My team at the Stanford Geospatial Center is working on a geo referencing project of historic maps of Africa, all from the 1700s (I believe). We are in the process of setting up the best workflow for referencing the continental maps but are having some difficulty in identifying the most suitable projection in ArcGIS to use as the base to reference to.

 

Most of the maps include a graticule which helps narrow down the projection type to some kind of Equatorial projection. We've played with a few stock projections types in ArcGIS and came up with the following images based on the Van Der Grinten projection.

 

The graticule looked like a match between the base and the image but as you can see it wasn't.

 

What I'm hoping is someone here with more projection experience than I will be able to spot the correct type of projection to use as the base from the graticule and the uniform deformation in the rectified image.

 

Any ideas?

 

 

 

 

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GIS Reference and Instruction Specialist, Stanford Geospatial Center.

 

www.mapbliss.com

 


#2
David Medeiros

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2nd order rectification

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#3
David Medeiros

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3rd order rectification

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#4
Strebe

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Probably sinusoidal but won't be able to tell for certain until I get home. What have you tried besides van der Grinten? (Which it certainly is not.)

--daan Strebe

#5
Fran├žois Goulet

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I used a sinusoidal projection to map Africa once and it looked like that... It's a wild guess though.



#6
David Medeiros

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Probably sinusoidal but won't be able to tell for certain until I get home. What have you tried besides van der Grinten? (Which it certainly is not.)

--daan Strebe

 

Agreed, that was one of my assitants best guess at the time.

 

The graticule for van der grinten looks very simair but the Africa map has more curvature. Interestingly when rectified to van der grinten the center of the map is un changed but the edges warp a lot (as shown in the pic above). I thought this might mean we were on the right track with a spherical projection.

 

Will try sinusoidal next.


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#7
souvik.gis

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If you are rectifying Raster Image, why not try Geographical Coordinate system with only Lat/long and a suitable Datum?



#8
David Medeiros

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If you are rectifying Raster Image, why not try Geographical Coordinate system with only Lat/long and a suitable Datum?

 

Because we are trying to minimize the warp associated with the rectification. Matching the general type of projection, even if not exact will keep the original image looking more or less the same.

 

FYI, it was sinusoidal. Very close match. Thanks all!


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