Symbols: Importing and Exporting

Symbols and Files

With a few exceptions, modeling programs store all related data in a single "drawing file" (.dwg in Autocad, .3dm in Rhino). This makes it easy to make a backup or give a copy to someone. However, design projects often involve multiple people, and an office may use standard symbols in each project.

Block "Libraries"

Since most modeling software doesn't really provide a customizable "library" of data (form•Z is an exception here), users collect useful blocks in folders and import them as needed into projects. In this way the create an ad-hoc library.

Typically, to use a block in a file you must create it there or import it to that file. Once imported, it can be used any number of times (including 0 times, in which case it takes up space in the file without benefit). To use the same block in a different project you must (again) create it there or import it.

A 'standard' block that is used in multiple projects is duplicated in each. Updating it means opening each project and re-importing the modified block.

Using a Model as a Block

ANY existing model or drawing can be added to another model or drawing as a block in the second file. The original model's ORIGIN automatically becomes the BLOCK insertion point. In Rhino this is done with "File > Insert ...".

Saving a Block as a Model

You can also save any block as it's own file if you wish. The resulting file will have all the block geometry, positioned relative to the insertion point (which becomes the model origin). Use "Edit > Blocks > Block Manager > Export" to do this.

Change Propagation

When a block is creating by Inserting a file, the geometry in the original file is copied, not linked. Changing the original file won't (usually) cause the block to change (in Rhino the "Edit > Blocks > Block Manager" can be used to control this behavior). On complex projects with multiple designers, judicious use of blocks and definition updates can make it easier to manage the model.

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