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Geospatial Analysis with AutoCAD Map 3D

Engineering software offers GIS querying and analysis capabilities that take you beyond data management

Autodesk's AutoCAD Map 3D is widely known as an engineering program for creating and managing CAD and spatial data. However, did you know that AutoCAD Map 3D also has querying and geospatial analysis capabilities?

That’s right! AutoCAD Map 3D is a true engineering GIS software program: a program that embraces CAD and geospatial data; a program that integrates this data in a manner that respects both engineering design and GIS requirements; a program that not only helps you create and manage both types of data, but also helps you analyze this data.

Whether your focus is CAD or GIS, geospatial analysis can help you derive more value from your data and aid in better decision making. Whether you are creating a bill of materials, designing a new utility network, or conducting a feasibility study, geospatial analysis is an important addition to your CAD and GIS skill set.

This article introduces some of the geospatial analysis capabilities of AutoCAD Map 3D by addressing the role of queries, thematic mapping, buffer analysis, topology analysis, and 3D surfaces in analyzing your CAD and GIS data. In future articles in this series, I'll offer more detailed guidance to help you make the most of these tools.

In this example, a query is used to identify all cast iron water mains.

Queries
The geospatial query is a simple, yet powerful geospatial analysis tool. Queries are used to retrieve a subset of objects or features by attribute and/or location. They help you to limit the data that you’re working with, isolate specific objects and features, and otherwise discover patterns in your data. Queries help you to answer questions such as:

•   Where are all the cast iron water mains greater than 50 years old?
•   What is the total length of overhead conductor in a subdivision?
•   How many blocks named METER are in my drawing?

Whether you are working with CAD data (such as DWG files) or feature data (including GIS data sources), AutoCAD Map 3D supports the ability to query your data by specific attribute information (e.g., material type = "cast iron") and/or geographic location (e.g., number of meters within a specific area).

Thematic Mapping
Thematic mapping uses display properties such as color, line type, and symbology to visualize attribute data corresponding to specific map features and to help identify and compare spatial patterns. For example, the common road map that you can purchase from your local gas station is a thematic map that uses different line styles to help distinguish the various road types such as highways, collector roads, and local streets. Another common example is the municipal zoning map in which areas are color-coded according to their zoning designation, such as residential, commercial, and industrial.

Attempting to create a thematic map in CAD requires separating your CAD entities into different layers — a lengthy and error-prone process. However, thematic mapping is faster and easier when you use the built-in thematic mapping functionality in AutoCAD Map 3D.

Use Thematic mapping to quickly call out various types of CAD entities in a map.

Theme your point, line, and polygon features and control color, line style, symbology, and polygon fill styles to create thematic maps even if your data resides in external data resources such as ESRI SHP files or Oracle databases. You can also generate a corresponding legend with the built-in legend creation tool.

Buffer Analysis
A buffer is a polygon that is created at a specified distance from a feature or set of features. For example, a 30-foot buffer around a point is a circle with a 30-foot radius. Buffers are used to determine proximity and to select other features for reporting or additional analysis. For example, municipal rezoning applications typically require that all affected property owners be notified of the proposed change in zoning. Affected properties are identified by determining which parcels lie within a stipulated distance (the buffer distance) of the parcel being considered for rezoning. These parcels and their corresponding address information are then used to generate the rezoning notification.

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