Hi Dave!
You are fortunate in that these maps have a very good graticule which of course makes the task so much easier.
But understand that MI does not warp or alter raster images in any way.
Instead, it warps overlaid vector tables to fit the raster, and the fit is determined by the information you assemble when registering the raster image for use in MapInfo.
I am sure you know how this is done, and my only advice for you is to try and determine the projection by trial and error.
Pick one map and try some of the most likely projections and see how they each will fit a vector map of the same area.
Unsuitable projections will give residual errors of several pixels, and the vector map will not fit evenly over the area.
To me, this approach seems a lot easier than trying to warp the raster images into some other projection.
First, I think you need to know the original projection even then, and second, reprojecting them would alter an historical document which you always have to be careful about doing.
Best regards Mats.E
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"David T. Hughes" <[EMAIL PROTECTED]>
2005-02-26 04:16 |
|
Okay. I know that there ARE different projections, and that they are
different mathematical models of the world (spheroids, mercator, etc. etc.).
Here's the deal that has me beat:
I'm working with some antique maps of Native American treaty boundaries (you
can see them at
http://memory.loc.gov/cgi-bin/query/r?ammem/gmd:@field([EMAIL PROTECTED](g3701em+
gct00002 -- then click on the map of Alabama in the top left). Drafted in
1897 or 1898. They are in the public domain here but are still a very
important resource for people working on Enclosed Nations issues.
Anyhow, I want to use those as part of a MI series of searchable material
linking treaties, people, and times.
BUT, before I can do that I need to reproject them to something (ANYTHING!)
MI will understand. Since I don't know the original projection (I own the
original volume these came from) and cannot find any reference to it at all,
I'm stumped.
Not knowing the original projection makes it very tortuous to bring them as
anything at all that links to the other maps (all are in UTM NAD1927, Zone
14/15, North America).
Is there a simple way in MI 7.5 (or any external utility freely available)
to load the SID or TIF or BMP to a program, click on 4 or more lat/lon
interesections, enter the coordinates of the intersections, and then tell
the program "Okay, now warp it into a projection my software knows about"?
I'm out of options on this, and really need to find a patch by the end of
this semester.
Thanks in advance to anyone who has any ideas at all -- I'll even store the
results and put together a SUM at the end of the mail if there is interst
from others in the same esoteric use.
Dave Hughes
Newton, Kansas USA
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