ArcSDE CAD Client #5
Storing everything all the time is not always best. My wife is quick to remind me of that fact whenever the topic of our garages storage capacity is mentioned. I admit that I have pack-rat tendencies, although strangely I am not very accommodating to anyone else in the family contributing to the garage archives… Storing what you need, or what you will use is generally accepted as more practical… Unless you can’t decide if maybe in the future that broken garage spring might come in handy as a replacement part for some as yet un-invented contraption?
As mentioned earlier in the series ArcSDE CAD Client can store a binary copy of CAD features as a special BLOB (Binary Large Object) attribute of an ArcSDE feature. This binary copy retains all of the CAD symbology such as line weight, color, layer, etc… When data is stored in ArcSDE in this way I have a choice to either RETRIEVE the CAD version of the data or the ArcSDE geometric version of the data. Because symbolic variance is often a method of attribution all to itself in CAD data, extracting the CAD graphic properties when storing ArcSDE features from CAD data is a way to retain more of the intelligence of a CAD file. This data can also be useful when symbolizing ArcSDE features in non-CAD ArcSDE Client software like ArcGIS.
By default ArcSDE will only store geometry. You need to explicitly define which of the available CAD properties that you want to record in ArcSDE columns. Access to these properties will only be available to ArcGIS if they are configured for during the STORE process. Unlike a CAD feature dataset where the CAD properties are always included unless you explicitly hide them. When you save CAD data as ArcSDE features each feature is stored individually as a record in the ArcSDE spatial database layer. An ArcSDE representation of the feature based on the CAD geometry is stored as the feature’s “shape”. CAD Client must store data into a predefined ArcSDE layer. The schema of the layer is determined by the database administrator in Oracle or SQL Server or the ArcSDE supported database of your choice. If you would like to extract the CAD graphic properties an make them accessible by ArcGIS you will need to establish a column or field in the schema that can be used to store that graphic property value; columns like CADColor, CADLayer, etc…
In the STORE Template wizard you establish a paring between extractable CAD graphic properties and the columns of the target ArcSDE layer, which in turn is the schema established for the attribute table by the ArcSDE/database administrator. The template is the place where you select which if any CAD attributes you would like to store in columns in the database when you STORE CAD data in ArcSDE using CAD Client.
To store extended attribute information such as AtutoCAD block attributes, Microstation tags, Xdata, MSlinks or Object Data you will have to build a custom application using the API of AutoCAD or Microstation to read the information and then the Automation, C-Api, AutoLisp or Basic ArcSDE CAD Client API’s to store that additional data.