Calling all projection and image registration buffs:
I'm having trouble with a 1:24,000 orthophoto (1ft
pixel) in that it displays differently in MapInfo than in ArcView. In
MapInfo the image appears "shorter" than in ArcView, or another way to say it is
that in ArcView the image seems "stretched" along the North/South Axis.
The main question I have is: which one is correct? (Visually, to me, it
seems the MapInfo image looks more normal, but I need to be sure)
According to my production staff, the file is set in
both headers (.tab, .tfw) to be displayed in Lat/Long WGS 84, and they
argue with me that both registration files are correct. In my mind,
however, they cannot BOTH be correct if the image looks distinctly
different even though it is displayed with the same projection and
datum. It's hard for me to compare both headers due to the fact that
they handle things differently- MapInfo uses a set of control points where
the .tfw appears to use an anchor pixel with info on the pixel width and
height. I did notice in the .tfw that the pixel width/height dimensions
(1st and 4th lines of the file) are different by about 10%. Is this due to
the Lat/Long (un)projection, or does this signify an error in the .tfw
registration file, thereby deeming the MapInfo .tab registration to be the
correct one? Also, the MapInfo .tab file specifies the control points on
the image to be at (0,0) - (1,0) - (0,1); I know that these points should
be spread out over the image, but does this matter in a Lat/Long setting?
Or, could both packages be correct, and the difference
simply be an inherent part of the different methodologies used between software
packages?
The header files (.tab, .tfw) are copied below if this helps.........
TIA,
Chris
MAPINFO HEADER:
!table
!version 300
!charset WindowsLatin1
!version 300
!charset WindowsLatin1
Definition Table
File "color_1ft.tif"
Type "RASTER"
(-81.968077,26.477339) (0,0) Label "Pt 1",
(-81.968074,26.477339) (1,0) Label "Pt 2",
(-81.968077,26.477336) (0,1) Label "Pt 3"
CoordSys Earth Projection 1, 104
Units "degree"
File "color_1ft.tif"
Type "RASTER"
(-81.968077,26.477339) (0,0) Label "Pt 1",
(-81.968074,26.477339) (1,0) Label "Pt 2",
(-81.968077,26.477336) (0,1) Label "Pt 3"
CoordSys Earth Projection 1, 104
Units "degree"
ARCVIEW HEADER:
0.00000306217244
0.0
0.0
-0.00000274156806
-81.96807699999999
26.47733900000000
0.0
0.0
-0.00000274156806
-81.96807699999999
26.47733900000000
