Scanned Map. GCS_Clarke_1880->WGS84

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12-21-2017 06:29 PM
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New Contributor

Hello,

Struggling a bit with transforming/reprojecting a scanned map of Southern Ghana from GCS_Clarke_1880 to WGS84 in ArcGIS 10.5. I need it to be in the same coordinate system as the Worldview-3 imagery I am using in ArcGIS and Erdas IMAGINE. Here's what I have done:

1. Scanned the map as a TIF, imported into ArcGIS 10.5 and defined the projection as Clarke 1880 (the original projection of the map).

2. Georeferenced the map.

3. Attempted to use the "Project Raster" tool to change it from GCS_Clarke_1880 to WGS84, but getting errors that the transformation is not valid. See below for screen shot.

Map Problems - Album on Imgur 

What am I doing wrong here? Should I be using a different tool? Any help is appreciated.

Thank you,

S

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MVP Esteemed Contributor

It says the map is in a transverse Mercator projection not a Geographic Coordinate System (aka, a GCS) with  Clarke_1880 datum.  Can you check the coordinate system of the map.  I doubt that Ghana would use an Geographic coordinate system to produce a map.  Also WGS-84 is a datum.  There is a GCS with that datum (ie GCS-WGS-84) but there also UTM projections with that datum as well. 

I suspect the datum shift may not be the root of your problem, if the above is true.

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MVP Esteemed Contributor

It says the map is in a transverse Mercator projection not a Geographic Coordinate System (aka, a GCS) with  Clarke_1880 datum.  Can you check the coordinate system of the map.  I doubt that Ghana would use an Geographic coordinate system to produce a map.  Also WGS-84 is a datum.  There is a GCS with that datum (ie GCS-WGS-84) but there also UTM projections with that datum as well. 

I suspect the datum shift may not be the root of your problem, if the above is true.

View solution in original post

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New Contributor

Thank you for your response! Indeed, you are right. I entirely misinterpreted the map info. Having new issues with georeferencing the false UTM coordinates, though. I will make a separate thread. 

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