Andrew

The scales shouldn't matter when moving vectors around. Issues like this are
pretty common. A couple of things to look at - 

1. The coordinate system of both your tables needs to be be BNG - check it
is. MI also supports displaying them in different coordinate systems. Check
that the coordinate system of the mapper window they are working in is also
BNG. Note that rasters can only be displayed in the coordinate system they
were registered in (MI doesn't warp rasters) so if you have a lat/long
registered raster in your map it will override any statements you issue.

2. In addition, MapInfo has its own coordinate system - the session
coordinate system - that defaults to lat/long. You need to use the MapBasic
window to explicitly tell MI to use BNG.

3.If the first two have been covered, check that you are using the same
bounds for BNG. Using smaller bounds (the default is the whole earths
surface I believe) improves the accuracy.

4. The good news is that you can do all of this with a couple of lines in a
workspace, if you don't already have a MapBasic program you can extend. Look
at "Set Coordsys" and "Set Map Window". You can get the full BNG Coordsys
clause from the MapInfo.prj file in the program subdirectory

HTH

Paul Crisp

Syntegra
Innovation Place Delta Bank Road Newcastle NE11 9DJ
Tel 0191 461 4522 Fax 0191 460 1987


-----Original Message-----
From: Andrew Newman [mailto:[EMAIL PROTECTED]
Sent: 25 September 2003 10:23
To: [EMAIL PROTECTED]
Subject: MI-L Digitising Blues


Hello People,

Our Cartographers have recently started using MapInfo for cartographic
and data capture work, and they are experiencing problems when
digitising.

They are copying features from vector base maps and pasting them onto
an editable layer (another table) they then zoom in on the feature
copied and they discover that their copy of the feature appears offset
from the original by a few millimeters.  They are digitising in both
MapInfo 6 & 7 and are working in British National Grid projection.

I suspect that the problem is caused when the scale being used to view
the data is more zoomed in that the scale at which the data was
captured, or that the zoom is beyond the accuracy of the coordinate
system.  I would appreciate any guidance on what the problem is and how
to avoid it.

Thanks Andrew




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