OD/DB features. Article 3.
OD/DB technology – objects’ characteristics definition; object models
OD/DB technology – the means of convenient andcomprehensive identification of any non-graphical characteristics of drawing/model objects in basic AutoCAD by users themselves. This is the method of creation of object models, which are convenient for software data analysis. Specifically it is a tool for object models creation from existing graphical models and/or AutoCAD drawings.
OD/DB technology involves attaching objects with non-graphical object type definitions (identifiers), together with the fields for descriptive data and non-graphical characteristics. AutoCAD has some internal features for that – the extended data (XData, XRecord etc.). There is connectivity with external databases.
The necessity or desirability of objects’ characteristics definition exists for almost any drawing object, in the majority of drawings/models. With the help of OD/DB, it is possible to determine any number and variety of characteristics for all drawing/model objects. Furthermore, one can provide convenient software processing of the data.
Non-graphical definition of characteristics using descriptive data (XData, XRecord etc.), external databases is a comprehensive, direct way for object’ characteristics definition represented by any AutoCAD graphical primitive. The most commonly used graphical methods of characteristics’ definition – text objects, attributes, multiple layers, and so on – are indirect or not suitable for all types of primitives, and, one way or another, are not universal.
Non-graphical object types’ identifiers and non-graphical definition of their characteristics do not depend on the type of graphical primitive, on other graphical properties and parameters of the element, do not load the drawing – they exist "in parallel". Moreover, they help to provide a homogeneous definition of objects and their characteristics, which makes it easier to organize its direct and uniform software manipulation, software analysis.
Any drawing/model element, any type of AutoCAD primitives can be attached with the records with field sets for any desired characteristics as additional non-graphical data (XData, XRecord, external databases etc.). If necessary, one graphical element can be attached with any number of such records either with the same or different field sets. Thus, any AutoCAD drawing/model graphical element can be defined as an object of a specific type (or as several different types of objects) making it possible to describe any object characteristics.
Such models are designated here as object models, better designed for software analysis – as opposed to graphical models, designed primarily for human analysis.
Conversion of existing drawings/models into object ones can be done automatically based on differences in the graphical properties of objects of different types. In this case, graphical elements with same properties are automatically defined as objects of the corresponding type, and are attached with records with fields for the corresponding characteristics.
For users, the implementation of such capabilities with ready-made object definition files does not require any additional efforts at all. Object definitions and required fields for characteristic values are created automatically when drawing from the object menu. Editing field descriptions for characteristics, adding, deleting, changing them is available to any user and is transparent for understanding. The description of the field of any characteristic in object definition file can occupy single line.
OD/DB technology is intended to provide users with a set of basic tools that allow them to define characteristic values, view, analyze, edit, and unload these values. Thus, this technology involves providing users with sufficient similar capabilities for the main tasks, for any drawing subject, without the need of attracting programmers in general case.
The non-graphical object definition of drawing/model elements and the description of the non-graphical characteristics largely changes the essence and the creation meaning of drawings/models. A new type of product is created. Graphical object models become informational ones. Informational is not in the extended sense, expected from BIM, including formalization, simulation of processes, relationships, object relations, but providing the mandatory BIM-models component – object identification and characterization. In other words, allowing direct, unified object data software processing. Allowing to prepare data for BIM and other information systems (GIS etc.), partly allowing to describe relations, object relationships.
Consequently, object models are a transitional type from graphical models to fully informational – within basic AutoCAD graphical primitives’ workflow capabilities.
Translation: Sergey Sheviakov