What's New in ArcGIS 9.3 for CAD: MSD

I just got back from my first visit to the Grand Canyon. I have flown over the Grand Canyon countless times, but this time I walked right up to the edge of it. I was surprised at the many spots in the park’s public viewing areas that you can literally walk right up to the edge of the Grand Canyon without guard rails and look down! In some ways it was refreshing to see that people were trusted with some level of personal responsibility for not falling in, but at the same time as a parent of an active 4 yr old it was a little disconcerting!

I will try to resist metaphors for closing the chasm between GIS and CAD and simply introduce this series on what is new in ArcGIS 9.3 desktop for CAD. The list of new features in ArcGIS 9.3 desktop for CAD are few in number, however the magnitude, and scope of new uses for these features are many. I will expand on some of these in a series of posts following this one.

I will also make some references to the next release of, ArcGIS for AutoCAD here, which will be ready a short time after the general release of ArcGIS 9.3 desktop. ArcGIS 9.3 desktop is scheduled to start shipping at the beginning of July 2008.

Improvements in ArcGIS 9.3 desktop for CAD address the two most common needs expressed by GIS users for AutoCAD; the first, how do I share my GIS data with AutoCAD users? And secondly, how should I organize data in AutoCAD to make it the most useful in ArcGIS?

ArcGIS 9.3 now reads and writes GIS feature classes from and to AutoCAD files using a technique that employs standard AutoCAD extensible data constructs. ESRI’s implementation of this DWG encoding technique is called the Mapping Specification for DWG or MSD. If I create data in a DWG file using this data encoding technique I can specify GIS feature classes in AutoCAD files using standard AutoCAD drawing entities and data structures. The drawings are still plain DWG data with CAD data objects to define how the entities should be grouped and entity-specific feature attributes.

MSD’s main features are:

• The ability to store a named coordinate system inside the AutoCAD file
• The ability to define which entities in a drawing qualify for a specific GIS feature class
• The ability to define a set of attributes for a given GIS feature class
• The ability to store feature attributes on entities in the drawing

The ArcGIS 9.3 EXPORT TO CAD geoprocessing tool creates MSD-defined GIS feature classes whenever GIS feature classes are written to AutoCAD files. Instead of forcing my AutoCAD friends to understand a Shapefile, other intermediate GIS formats, or buy ad-on products, I now give them attributed GIS feature classes directly usable in their native AutoCAD environment.

Future versions of the no-cost ArcGIS for AutoCAD will include ESRI’s version of tools to create, edit and view MSD stored feature classes within the DWG file. I can also build tools with my own AutoCAD API’s to work with the MSD data. The new ESRI Resource Center ArcGIS 9.3 content will soon include a detailed specification and examples of the DWG data constructs used for MSD.

ArcGIS 9.3 desktop, ArcMap/ArcCatalog will recognize MSD feature classes whenever it reads an AutoCAD file (dwg/dxf) with data is encoded according MSD. Working with the MSD-defined CAD feature classes will be exactly the same as working with the standard POINT, POLYLINE, POLYGON, MULTIPATCH and ANNOTATION CAD feature classes. MSD-defined CAD feature classes will appear along with these standard CAD feature classes and will include just those attributes I have defined for the MSD feature class.

Because MSD leverages the existing CAD techniques I already use in my CAD standards to organize data by layers, color and other symbolic variations, I don’t have to require a change in the way my draftsman work. The MSD feature class definition is like a stored query, or the definition query of an ArcMap layer. MSD feature classes are simply pre-filtered CAD data with their own feature attributes stored within a DWG file.

More to come…