Image Registration Issues (Mapinfo Pro 8.0)

[Adam]

Hi Listers,

I've got a query regarding the registration of images. I am currently
doing a project involving 'sewing' digitised archived maps to a
current digital cadastre. A big job and with its inherent errors and a
time consuming job too.

My problem is that when I have registered one map with a manangeable
error margin and correct projection, I will import another map to see
whether the map 'stitch' is ok between two or more maps. However, when
I import the current map shifts noticably from the current
registration, hence distorting my registration.

I've experimented and found that this shift occurs on any any
registered raster map when swapping them in and out using layer
control view options or loading them up. In some cases, both maps
when viewed individually may be relatively accurate relative to my
principle vector map, but when viewed together one or the other
'shifts' depending on the which has been viewed/imported last. Ive
double checked my registration projection is consistent...and it is.
I've also started from scratch thinking that having multiple pre-
registered raster images open whilst working with the registration of
another maybe screwing with the previous rectified rasters...so I open
them and work on them individually then later import them in together,
but I still get the 'shift'.

- I'm all out of ideas, with no sure idea of whats happening with the
registration. My maps are goin from the bayeux tapestry to abstract
art in some cases.

Any help would be greatly appreciated.

Adam

[Adam]

Sorry, to clarify i wrote:

"...when I import the current map shifts noticably from the current

registration, hence distorting my registration."

I meant to say its not my registered data points that are changing,
but something in the map window causing the raster to shift when in
view. As far as I know its not an issue with the associated .tab file
linked with the image...

Thanks,

adam

[Rob Schneider - Aurchem Exploration]

Are these aerial photos? Any oblique photo (or non-north) photo when
viewed with another will have problems due to registration. The vector
data will be 'translated' to line up with your registration but when 2
slightly different translated images are used the vector data can only
be accurate to one of them.
Hope this makes sense,
Rob

> .
>
>

[Mats Elfström]

Hi Adam!

First of all, you need to be sure that you are using the correct
projection/coordinate system for the image registration. If you are,
then two adjacent sheets should appear in their relative position, and
with respect to vector data.
If not, the way MI 8 deals with georeferenced images may play unexpected tricks.
MI tries to adjust the vector data to fit the image, not the other way
around. It cannot alter or reproject the images (this changed in later
versions).
The mapper window tries its best to fit the vector data to the control
points, changing the adaptation after view and zoom level, but cannot
readily cope with more than one raster image at the time.
In order to do that, the images would perhaps need to be slightly
rotaded or scaled, which Mapinfo cannot do. I believe it is the first
found image that sets the parameters for the mapper window.

If you need to reproject the images I suggest you upgrade, because as
from version 8.5, you can do that.

HTH Mats.E

2008/8/4 Rob Schneider - Aurchem Exploration <r...@aurchem.ca>:

[Adam]

Heya,

Thanks everyone for the support, however Mats, i think that you have
it correct. I notice that when I make a bad registration (linear, too
few points). I notice that the vector map can distort hugely in
proportion to the points that I have made. You say:

"MI tries to adjust the vector data to fit the image, not the other
way around. It cannot alter or reproject the images (this changed in
later versions)."

This makes complete sense, and would explain why importing other
registered maps will distort my original vector base maps, as you
explain it tries to compensate with the new registered x,y map points
between the other image. This seems silly for MI 8 to do this but at
least now i think i know what is goin on...

I work for government so i will have to wait for the public to get me
an new mapinfo upgrade...maybe MI 9 soon!
As this registration project is long term, i think i can just keep
registering and archive my .tab registered coordinate files, and let a
later version of MI do the rest...

Thanks heaps!

Adam J