Eric,
Is the underlying cause that you are describing related to the
programming anomaly which causes a non-cosmetic layer, created AFTER
original layers in a workspace are created by translating AutoCAD R13
.dxf files into MapInfo tables, to collapse to the 'limits' of the .dxf
file(s)?
The collapsing of new objects (definitely lines and polygons, and
presumably points) to the nearest edge of the minimum bounding rectangle
which would coincide to the .dxf 'limits' or 'extent' cannot be stopped
without correctly executing the Bounds clause in a CoordSys statement.
I managed to do this only once; otherwise, I have to return to AutoCAD
and create a dummy rectangle with extents large enough to encompass the
MapInfo bounds I need to work in. When the .dxf of this rectangle is
converted and added to the workspace, object creation is no longer
impaired.
Conditions are: MI4.5, Indiana State Plane Coordinates, 1983, units=feet
David Bruce
[EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
>
> Thanks for posting this, Steve. As it so happens, a MapInfo partner
> mentioned the same issue at the Partner Conference! To some folks, the
> reason why this issue has not been addressed by 'bounding' the cosmetic
> layer may not be completely obvious.
>
> Currently, when the cosmetic layer is created, it is assigned a coordinate
> system that is basically the same as that of the first layer in the map.
> So, if you have a MapBasic or Workspace command that says:
>
> Map from XXXX, YYYY, etc.
>
> the cosmetic layer will have the same coordinate system as table XXXX!.
> This is just a convention established long ago which creates a cosmetic
> layer with a reasonable coordinate system and avoids having to prompt the
> user for information that they might not know or care about. They might not
> even use the cosmetic layer.
>
> However, the coordinate system is unbounded because we have no idea if
> people will want to add objects to this layer outside those bounds. I
> guess having ones data truncated to the bounds seems worse than the
> opposite behavior described by Steve.
>
> One way we might improve this would be to add an optional cosmetic layer
> coordinate system clause to the "Map" command. Whatever it specified would
> be accepted outside of error conditions such as Non-earth and earth systems
> mixing. This would free developers up from the caring about the first
> table.
> The second part of my idea would be to add a user preference specifying
> some form of these same options for new Map Windows created. Perhaps
> something as simple as a choice of bounding or unbounding the cosmetic
> layer or possibly explicit preferences as to the coordinate system. whether
> it is derived from the first table or not, etc. With some extra work, a
> Set Map Layer Cosmetic command could even alter the system after creation
>
> Your input is appreciated.
>
> Eric Blasenheim
> MapInfo Corporation
>
> Steve Wallace <[EMAIL PROTECTED]> on 11/18/99 07:45:49 PM
>
> To: MapInfo-L <[EMAIL PROTECTED]>
> cc: (bcc: Eric Blasenheim/MapInfo Corp)
> Subject: Problem discovered w/Bounds Clause
>
> Something that might interest those of you who use the MapInfo "Bounds"
> clause to increase the precision of your maps -- don't use the Cosmetic
> Layer to transfer data around. I had been wondering why some of my
> points/lines would move around from time to time. The distances were very
> small, to the point where some might argue, "Why does it matter?" But the
> problem is, the Object Processing notices these small differences, leaving
> you will all kinds of unwanted spikes and slivers when you split or erase
> objects.
>
> The problem is that I, like many of you, use the Cosmetic Layer when
> editing maps. In fact, when I first noticed the problem was going through
> the prescribed method taught by MapInfo for fixing self-intersecting
> polygon errors flagged by MapCheck. When I copied a string of nodes from my
> bounded map to the cosmetic layer, then transformed to a region and went
> back to process this against my original, the region in the cosmetic layer
> was slightly offset from the original.
>
> This is because the Cosmetic Layer is unbounded -- you lose any increased
> precision from your bounded objects when you paste them info the cosmetic
> layer.
>
> WORK-AROUND: If you work with bounded data, create a blank layer with the
> same bounds clause and use it like you would your cosmetic layer when you
> need to put/process objects in a temporary layer.
>
> This certainly explains why I have so many unwanted artifacts in my maps...
>
> Steve Wallace
> GIS & Market Information Manager
> Florida Farm Bureau Insurance Companies
>
> ----------------------------------------------------------------------
> To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
> "unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
----------------------------------------------------------------------
To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put
"unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
