topology creation error "Intersections Detected"

[planner1]

Hi,

I'm attempting to create several UNION OVERLAYs between already created topologies originating from shp files.  Im using AutoCAD Map 3D 2009 and Autcad Civil3D 2011.

The first UNION OVERLAY works fine and the new resultant topology created (eg. A+B).  However, when attempting to create the second UNION - [A+B] + C, the topology fails with the same failure "Intersections Detected".

I suppose the original shp files are complicated shapes but I have applied drawing celanup before creating topologys.

ANy assistanance would be helpful in how to overcome the "Intersections Detected" error woiuld be great.

Thanks

[Murph_Map]

One option is to use the Data connect to bring in the shp file(s) and use the overlay tools there. It's more forgiving on the intersections. Then import the sdf files it creates into your C3D project.

[tzzzzoddhepworth4253]

By the way, I hope you're aware that if you have C3D 2011, you have the functionality of Map3D 2011 - check out the Task-Based Geospatial or Tool-Based Geospatial workspaces.  Or if you want the best of both worlds, use your Civil3D workspace and type in "MAPWSPACE" to use the map tools with your C3D ribbon.  I'm finding too many of the folks I work with are unaware of the GIS side of C3D....

All the best!

TdH

[planner1]

Murph

Many thanks for reply.

I'm attempting to create unions for several sets of shp files before exporting them to SDF for further analysis with other SDF data via FDO connection.  I'm going down this route as Ive already tried the FEATURE OVERLAY option for the same data which has also failed I'm convinced due to the complextity of the object shape. 

Seems strange that the Typology option would not work. I have recently read a forum which suggests performing the TOPOLOGY OVERLAY using 'Intersect' as opposed to 'Union' option. I have yet to try this option but not convinced.

I was wondering if there is perhaps anything I could use in drawing CLEAN UP in terms of rules or tollorances on the original data that might help prior to creating the TYPOLOGYs?

[tzzzzoddhepworth4253]

There are sliver tolerances in the intersection/overlay routine that are similar to the Cleanup tolerances.

Check out the Map Tutorials that you have on your HDD with a full install - there is an exercise on Pg 273 that might help clarify the Sliver Tolerance as part of a flood overlay to compare to GIS layers.