by Paul Richard and Jim Fitzgerald

Chapter 16 - Blocks and Block Attributes

• Create and insert blocks• Understand the difference between a block definition and a block reference• Explore the different types of blocks• Create unit blocks that can be inserted with different x and y scale factors• Manage block object properties such as layer, color, linetype, and lineweight• Understand the significance of creating blocks on Layer 0• Insert drawing files as blocks using Windows Explorer• Create a drawing file (DWG) out of an internal block• Create and update block attributes• Extract block attributes to an AutoCAD table or external file• Use DesignCenter to insert blocks• Use and customize tool palettes• Introduction to dynamic blocks• Use Content Explorer to browse DWG files to locate and insert drawing information

Brief Definition: Block definition – A user-defined collection of drawing objects assigned a base point and a name that is stored centrally in a drawing.

Brief Definition: Block reference – An instance of a block definition inserted in a drawing that references the central block definition drawing data.

Every time a block is inserted in a drawing it refers back to the centrally located block definition. In fact, when a block is inserted in a drawing it is referred to as a block reference because it refers back to the block definition to determine its appearance and other properties.

The BLOCK command creates a block definition using the objects you select with the name specified via the Block Definition dialog box.

Starting the BLOCK command displays the Block Definition dialog box

The Objects area allows you to select the objects to include in the new block definition if there are none already selected in the drawing, as well as to indicate what to do with the selected objects after the block definition is created.

All that you need to specify when inserting a block is the following:

• Block name• Insertion point• x, y, and z scale• Rotation angle

Specify Insertion Point

Specify Rotation Angle

If the Uniform Scale check box was not selected when the block was created,you can specify different x, y, and z scale factors when a block isinserted so that the block can be scaled along a single axis.

Unit block: A block or symboldrawn within a 1 x 1 unit squarethat is inserted in the drawing withdifferent x and y scales to achievedifferent final sizes.

Unit block: A block or symboldrawn within a 1 x 1 unit squarethat is inserted in the drawing withdifferent x and y scales to achievedifferent final sizes.

Structural lumber sectioninserted as a unit block withnonuniform scales

A block reference is considered a complex object just like a polyline, boundary hatch, or dimension. If the Allow exploding check box was selected when the block was created, you can explode a block back into its original individual subobjects either after it is inserted using the EXPLODE command or when it is inserted by selecting the Explode check box in the Insert dialog box.

To insert a drawing file via the Insert dialog box explained earlier, select the Browse…

You can use Windows® Explorer to drag-and-drop a drawing file directly into the current drawing.

The WBLOCK command, short for “write block”, writes a block definition to an external drawing file (DWG) with the file name and location you specify using any of the following methods:

• Write an existing block definition that is already defined internally in a drawing• Create a new block definition on-the-fly and write the block to an external drawing file.• Create a new block definition using all of the information in the drawing and write the block to an external drawing file.

Starting the WBLOCK command displays the Write Block dialog box. The Source area is the main area of the dialog box used to specify how to create the block.

The ATTDEF command creates an attribute definition via the AttributeDefinition dialog box.

NOTEThe Verify and Preset attribute modes work only when you enter attributes at the command prompt. They have no effect whenever the Edit Attributes dialog box is used to update attribute information.

NOTEThe Verify and Preset attribute modes work only when you enter attributes at the command prompt. They have no effect whenever the Edit Attributes dialog box is used to update attribute information.

• Update attribute values • Control attribute text options (text style, height, etc.)• Manage attribute object properties (layer, color, linetype, etc.)

The EATTEDIT command allows you to update attributes via the Enhanced Attribute Editor dialog box so that you can do the following:

The ATTEDIT command allows you to quickly update attribute values globally throughout an entire drawing at the same time.

The BATTMAN command allows you to update one or more block attribute definitions via the Block Attribute Manager dialog box

It is possible to extract property information from objects in drawings, including blocks and their attributes, to a formatted table in the current drawing or to an external file so that you can quickly create schedules, parts lists, bills of materials, and other tabular-type information based on the current drawing, or even multiple drawings.

TIPThe extracted data can even be merged and linked with information in a MicrosoftExcel® spreadsheet so that is possible to include additional external information.

TIPThe extracted data can even be merged and linked with information in a MicrosoftExcel® spreadsheet so that is possible to include additional external information.

The TEXT option Tab allows you to control the text properties of the currently selected attribute definition.

The REFEDIT command, which was originally created to edit xrefs, can be used to quickly redefine a block “in-place” without having to explode the block and recreate it using the BLOCK command as explained above.

The ADCENTER command displays the DesignCenter window so that you can locate and insert drawing content from other drawings located on your computer, network, or Internet.

The DesignCenter toolbar provides the navigation tools and display options:

The DesignCenter Propertiesshortcut menu

Tool palettes are highly customizable palette-type windows that allow you to group and organize blocks, hatch patterns, and even commands, using graphical icons on easily accessible palettes organized in a series of named tabs.

Dynamic blocks are multipurpose blocks that can be changed after they are inserted using special grips that allow you to display multiple block views, sizes, block behavior, and more.

NOTEAll dynamic blocks have a lightning bolt in the lower right corner of their tool palette Icon to indicate that they can be dynamically updated after they are inserted. Inserting and updating dynamic blocks is explained later in this section.

NOTEAll dynamic blocks have a lightning bolt in the lower right corner of their tool palette Icon to indicate that they can be dynamically updated after they are inserted. Inserting and updating dynamic blocks is explained later in this section.

Controlling Tool PalettesBecause they utilize the palette-type window, tool palettes can be hidden when you are not using them via the Auto-hide palette feature, as well as made transparent so that you can see through them to your drawing below using the Transparency palette feature. These and other features can be controlled via the Properties shortcut menu that can be displayed by clicking on the Properties button at the top of the palette title bar

TIPThe Auto-hide feature can also be quickly turned on and off via the Auto-hide button located directly above the Properties button

TIPThe Auto-hide feature can also be quickly turned on and off via the Auto-hide button located directly above the Properties button

Using dynamic blocks, you typically insert a generic version of the block and then use the special grips shown in the following table to update it dynamically:

by Paul Richard and Jim Fitzgerald

Chapter 17 – Working with Xrefs and Images

Referencing an external drawing• Attach vs. Overlay• Loading and unloading xrefs• Binding and xref• Editing xrefs• Controlling the path stored with an xref• Attaching raster images• Controlling the brightness and contrast of a raster image• Using DWF Underlays• Using DGN Underlays• Creating a transmittal set of drawings

Located on the Insert tab of the ribbon, the Reference panel provides most of the tools needed to work with the different types of reference files.

Xrefs, raster images, and underlay files are all managed using the External References palette

Xrefs are similar to blocks in that they are placed and behave like blocks. While they are similar, there are notable exceptions

• When you insert a block you are placing a reference to a block definition

• When you place an xref, you are directly referencing an external drawing file

Any drawing can be attached as an xref to another xref, a concept knownas nesting. To view nested xrefs, select the Tree View button on the FileReferences pane of the External References palette.

If AutoCAD detects circular xrefs, it will display a warning that circular references are and ask whether you want to continue. If you choose Yes, AutoCAD will break the circular reference and proceed with loading the xref.

When you attach an xref, you create a link to an external drawing file in your drawing. You can attach an xref either by selecting Attach DWG… from the drop-down or right-click menu in the External References palette or via the Attach tool on the Reference panel.

• The Attach button• Nested Xrefs • Attach vs. Overlay

The Attach option tells AutoCAD to load this drawing as a nested xref.

The Overlay option tells AutoCAD to ignore the reference as a nested xref.

Full path: If the Path type is set to Full path, AutoCAD stores the entire path

Relative path: Using the Relative path option, AutoCAD will store the location of the drawing file relative to the current drawing file

No path: Using No path, AutoCAD will only store the xref drawing name and no path information.

When you attach an xref, you create a link to an external drawing file inyour drawing. You can attach an xref either by selecting Attach DWG...from the drop-down or right-click menu in the External References palette or via the Attach tool on the Reference panel. Once you’ve selected a drawing, and select OPEN, AutoCAD displays the Attach External Reference dialog box

The External References palette is the main xref management tool.

When xrefs are attached to a drawing, the Manage Xrefs icon is displayed in the system tray in the lower-right corner

It is possible to edit an xref directly within the host drawing. The REFEDIT command also allows you to modify an xref from within your current drawing. This is known as edit reference in-place.

NOTEYou need to have the proper access privileges to the disk where the reference is stored in order to use the REFEDIT command on an xref. If you are referencing a read-only drawing from a CD or network drive, you will not be able to make changes to the xref.

NOTEYou need to have the proper access privileges to the disk where the reference is stored in order to use the REFEDIT command on an xref. If you are referencing a read-only drawing from a CD or network drive, you will not be able to make changes to the xref.

TIPTo prevent others from using the REFEDIT command to edit your drawing, remove the check from the Allow other users to Refedit current drawing option in the Open and Save tab of the Options dialog box.

TIPTo prevent others from using the REFEDIT command to edit your drawing, remove the check from the Allow other users to Refedit current drawing option in the Open and Save tab of the Options dialog box.

Of course, one of the easiest ways to make changes to an xref is to simply open the referenced drawing file with the OPEN command. When you make changes to the referenced drawing and save them, AutoCAD will notify you that changes have been made to the referenced drawing and allow you to update the xref by reloading it.

When you start the XCLIP command, AutoCAD asks you to select an xref and then presents a number of options. These are described in the following table:

Using the Bind menu item within the External References paletteallows you to bind an entire reference file to your current drawing.

Demand loading works by loading only the parts of an xref thatAutoCAD is actually showing. Layers that are turned off or frozen or anygeometry hidden by a clipping boundary are not loaded into your drawinguntil they are needed.

Raster images can enhance your drawings in a number of ways. They can provide colorful backgrounds with a company logo or background images for accurately tracing shapes. Architectural and civil drawings can benefit greatly by attaching satellite or aerial images to show site locations or conditions.

Raster images are treated and behave much the same way as xrefs but have additional controls to control image quality and transparency as well as brightness, contrast, and background fading.

The easiest way to control an image’s settings and appearance is to select it in the drawing so that the Image context tab of the ribbon allowing you easy access to the most useful image settings.

Like xrefs, you can apply clipping boundaries to images. The IMAGECLIP command allows you to define and control clipping boundaries associated with images

If an image is clipped, it controls the display of the clipping boundary. There are three settings for the IMAGEFRAME variable: 0, 1, and 2. These are described in the following table:

Some image file formats (such as GIF or PNG) support transparent pixels. When using images with transparency, you can turn the transparency on and off by selecting the Background Transparencybutton on the Options panel. If your image file format supports transparency, setting it to on will allow objects behind the image to be seenthrough the transparent pixels in the image.

The IMAGEADJUST command allows you to set the brightness, contrast and fade of a raster image

It is possible to reference DWF files in a similar fashion as xref drawings and raster images using the DWF Underlay feature by specifying a file path, insertion point, scale, and rotation angle.

You can attach a DWF underlay by selecting Attach DWF... from the drop-down menu in the External References palette, or you can bypass the External References palette and attach a DWF underlay directly using the DWFATTACH command.

You can attach a DWF underlay either by selecting Attach DWF... From the drop-down or right-click menu in the External References palette or by selecting the Attach tool on the Reference panel on the Insert tab of the ribbon.

You can attach a DGN underlay either by selecting Attach DGN... From the drop-down or right-click menu in the External References palette or by selecting the Attach tool on the Reference panel on the Insert tab of the ribbon.

AutoCAD also supports the referencing of PDF (Adobe Portable Document Format) files, the de facto standard for sharing electronic information. PDF underlays are attached using basically the same methods as DGN files. You can also control the PDF underlay settings after it is attached by selecting it in your drawing to display a context tab of the ribbon with the same settings and options as a DGN underlay.

The ETRANSMIT command helps solve the problem of sending incomplete files by compiling all external files into a separate folder or ZIP file. You can also create an email and automatically the files to the email.

When you choose the Transmittal Setups... button, AutoCAD displays the Transmittal Setups dialog box