Comparing SPDS GraphiCS Parametric Objects and AutoCAD Blocks

SPDS GraphiCS was introduced in 2000 as an add-on for the AutoCAD graphics platform. Its main tools were drawing annotations compliant with GOST standards, including leaders, axes, elevation markers, and boundary hatching.

The initial goal was to adapt AutoCAD to Russian requirements for design and engineering documentation. Over time, tools were added to speed up drawing production. Version 3 introduced tables with automatic reporting, followed later by parametric objects. Today, some of those features overlap with AutoCAD's static and dynamic blocks.

Which should you use, and when? What are the strengths and weaknesses of each approach? A feature-by-feature comparison has been published. However, developers naturally favor their own products, so user feedback offers another perspective. This article presents that perspective.

Svetlana Kaparova,

SPDS Project Manager

It would be wrong to pit AutoCAD blocks against SPDS GraphiCS objects. Each technology has its own applications, advantages, and limitations.

Still, online discussions often exaggerate how hard it is to create parametric objects in SPDS GraphiCS. Any user can—and should—build objects for their own tasks, since SPDS GraphiCS provides the necessary tools.

Let's examine whether creating parametric objects in SPDS GraphiCS is really harder than making AutoCAD dynamic blocks, and what benefits these objects provide.

The main argument for blocks is that they are easier to create and use than parametric objects in SPDS GraphiCS.

Let's see whether that is actually true.

Anyone can create a static block by pasting from the clipboard with Ctrl+Shift+V. However, its main advantage over a group of primitives is that all instances in a drawing can be redefined by editing any one instance. A static block is still just a collection of primitives—essentially a copy-and-paste operation.

Attributes can be added, but that does not fundamentally change the approach. Attribute values must be entered manually, pasted, or linked through fields to properties of the drawing objects or the block itself. Changing a block's geometry requires inserting another block and manually setting its properties again.

With AutoCAD 2006, Autodesk made a major advance by introducing dynamic blocks. This was a significant step forward that greatly improved their usability.

Even so, blocks still cannot interact with one another. Attribute values must be entered manually or through formulas, which users can accidentally break when editing block properties.

AutoCAD 2008 added block parameterization. Automation improved, but at a performance cost. Users of dynamic blocks know that large property tables and repeated instances can slow drawings significantly. Changing block parameters often causes noticeable delays in AutoCAD.

At the time, block technology was innovative and useful. There was no simple, accessible alternative.

The problem with block technology, surprisingly, lies in the blocks themselves. The original idea was sound: store block information once in a drawing and let all other instances reference the parent block. These references take up little file space and do not reduce performance. But this holds true only for static blocks.

A dynamic block remains a reference only until an instance is changed. It then becomes a separate anonymous block containing the original block's properties, primitives, and parameter tables. This slows drawing regeneration and increases file size.

You can test it by inserting a thousand instances of a dynamic block into an empty drawing, saving it, and checking the file size. Then change, for example, the visibility and geometry of every instance. After saving again, the file will be several times larger—the exact increase depends on block complexity—and performance will decline accordingly.

Autodesk recognizes this issue. Its industry-specific AutoCAD solutions, such as AutoCAD Electrical, use only static blocks. Blocks are inserted programmatically, while object data is stored outside the drawing in a separate database. The software retrieves those values when a block is edited or when specifications and reports are generated.

Parametric objects in SPDS GraphiCS avoid those and many other AutoCAD block limitations. They also offer features that standard blocks cannot provide without additional programming in VB, LISP, or similar languages.

Let's look at this in more detail:

unlike a block, a parametric object stores most of its information outside the drawing in the application's database. The drawing contains only visible geometry, attributes (properties), and the system information needed to display and use the object correctly. As a result, parametric objects impose much less load on the drawing than blocks with comparable features and do not slow regeneration;

parametric objects can have virtually unlimited interdependent parameters and visibility states, both within an object and through relationships with other drawing objects (Fig. 1). The main limit is the developer's imagination;

Fig. 1

• parametric objects can interact not only through geometry and relative position (geometric dependencies), but also by transferring custom properties (parametric dependencies) (Fig. 2);

Fig. 2

• although parametric objects are two-dimensional, geometry can be defined in the projection plane (views). Drawing representations can also be specified, including simplified, full, section, and other views (Fig. 3);

Fig. 3

• masking, stacking, and overlap can be controlled flexibly. Users who apply masks in blocks know that a mask can unexpectedly move to the front. Everything may look correct until the next time the drawing is opened, when the settings need to be redone. Parametric objects avoid this problem: the stacking order is explicitly defined by indexes (Fig. 4). For example, an object with ZOrder=100 is always covered by ZOrder=101 and covers ZOrder=99;

Fig. 4

intelligent dimensioning. Dimensions applied to a parametric object using SPDS GraphiCS tools retain the correct value regardless of the object's insertion scale (Fig. 5);

Fig. 5

• customizable user forms. Object properties can be selected from drop-down lists or data tables (Fig. 6), minimizing the risk of entering an incorrect value or parameter;

Fig. 6

• parametric objects can generate a complete bill of materials (which otherwise takes a substantial amount of design time) or other tabular reports. AutoCAD DATAEXTRACTION can count block instances, while reports based on parametric objects can include quantities, lengths, volumes, masses, and any physical or technical parameters. These values can then be processed as needed in the report (Fig. 7).

Fig. 7

Users often say that creating a parametric object is very difficult. Let's examine that claim step by step…

How many people at your company can build a truly functional, interactive block? Not merely change its visibility, a few stretch parameters, an array, or rotation, but make the length attribute scale-dependent, generate other attributes automatically from several parameters, and produce a complete specification from those blocks?

Not everyone realizes that the advanced interaction built into sophisticated dynamic blocks often relies on undocumented AutoCAD functions. Over time, this may make the blocks impossible to use or edit in newer AutoCAD versions.

Creating parametric objects is much easier than building dynamic blocks with similar functionality. The process is also more transparent, and the result is predictable.

Some designers are discouraged by the idea of having to “program” a parametric object. In fact, the scripting language is simple, has relatively few commands, and comes with detailed documentation and examples. SPDS GraphiCS also includes a script wizard that can eliminate the need to write code.

The program database also stores preconfigured script templates. A large library of ready-made objects is available for many applications. You can copy a similar object and adapt it to your needs.

Despite its name, SPDS GraphiCS is not limited to construction. Although the developer offers specialized products, SPDS GraphiCS objects can be created for virtually any design discipline and application.

The only limitation is the engineer's imagination.

Andrey Razygraev,

design engineer

LUKOIL-Volgogradneftepererabotka LLC