Creating Multiple CAD files from ArcGIS
GIS data sets can be huge, CAD files can be big. Sometimes big gets to be too big. ArcGIS is designed to accommodate large datasets by managing data from the source in ways that it doesn’t have to load all the data into memory while also employing database science to manage large queries and analysis. The drafting environments of AutoCAD and Microstation employ high-end graphics technology that promotes fast drawing of large datasets, but was never designed for large scale data management. Traditionally the CAD solution is to break up files into vertical or horizontal tiles that can be combined together by reference or to be viewed individually. Within the context of mapping these might be vertical tiles where different drawings are stacked on top of one another based on their content discipline. For example a layer of electrical distribution data, another drawing which contains the parcel and street data, another for water, sewer etc…
Another method of tiling is by geographic zone. Horizontal tiles include all of the data in each tile, but multiple tiles are used to cover a geographic area. This form of tiling also supports the idea of pages in a map book, or districts, zones or other arbitrary or gridded system of breaking up the map. These grids may be to distribute responsibility, or they may be based on, ownership or other geographic boundaries. When moving CAD data from a gridded tiling system into ArcGIS tools like APPEND and MERGE are common tools to create a seamless map.
To recreate the tiling systems of CAD, the EXPORT TO CAD tool can be used to generate multiple files from a single GIS data set. The key is to include a field in the data sets feature attribute table called DocPath. Within this field you can populate each feature’s DocPath value to control which Microstation or AutoCAD file the data should be exported to.
First you will create a polygon grid that represents the geographic boundaries of what would be each CAD file. Then populate each polygon with a value in a field called DocPath that represents each CAD file name. Then I use that grid to perform a spatial join or an overlay function and maybe the CALCULATE tool to include the CAD DocPath on each feature I intend to export. I then invoke the EXPORT TO CAD tool. Be sure to leave the Ignore Paths In Tables option of the EXPORT TO CAD tool unchecked because this is what this option is for.