Paper Space Tutorial
Paul A. Turvill, P.E.
Tee Square Graphics

Model Space is the "space" in which most of an AutoCAD drawing resides. Even though it didn't have a "space" designation attached to it until Release 11, Model Space has been around since AutoCAD was first developed - version 1.0. In Model Space, everything exists as in the real world, where 1 foot = 1 foot. The Model is, in fact, a 1:1 scale representation ("model") of whatever is to be represented by the drawing, be it a machine part, a bicycle, a house, a skyscraper, or a 50-mile stretch of proposed highway, complete with bridges, buried utilities and other details.

Paper Space, introduced in AutoCAD R11, can be considered a parallel realm within an AutoCAD drawing, but one where the "world" is based on the sheet of paper on which the final drawing will be printed or plotted. In Paper Space, the sheet of paper is represented in 1:1 scale, and the information contained in Model Space is presented in (floating) viewports, which may be scaled, rotated, and arranged in a literally infinite number of ways to create the final plotted drawing. Plotting is simplified, because the plot is always a 1:1 representation of what exists in Paper Space.

Preparing a (set of) AutoCAD drawing(s) which will utilize Paper Space can actually be much simpler than doing the same chore using Model Space alone. The more complex the project, the greater the justification for using Paper Space. Because Paper Space permits the user to define any number of discrete viewports into Model Space, it is no longer necessary to plan the scope of the work so as to fit single, plotted-to-scale drawing sheets; rather, it is possible (and preferable!) to commit an entire project (or major element of a project) to a single Model, and then use Paper Space viewports to make "snapshots" of the overall project for plotting to paper.

Even with this approach, however, a certain amount of planning is necessary. It is best to predict at the start, for example, what will be the best scale or set of scales that will be used for the final plotted output; this is important because text, dimensions, and other symbols need to be drawn in Model Space in sizes that will scale correctly to give the desired appearance in the final plots. Whether the project will be presented in one, three, a dozen, or 50 or more sheets isn't important; what is important is that the Model be constructed so that it will result in legible plots when it is committed to its final (set of) scale(s).

If, for example, drawing sheets of a Model will be plotted with the Model scaled at 1:100, and the user wants text to be plotted at 1/8", that text must be drawn 100/8" or 12.5" (1.04') high in Model Space. Text to be plotted at 3/32" would be 300/32" or 9.37" (0.78'), and so on. For most purposes, rounding to 12" (1') or 9" (0.75') would provide acceptable results.

Similarly, a set of dimension styles should be developed to result in similar results, and LTScale, block insertion scales, and other factors affecting the size and shape of various symbols should be planned with the final plot in mind.

Generally speaking, the process of making a Paper Space drawing can be simplified by the use of a properly formatted template drawing (*.dwt in AutoCAD R14). While it may contain virtually any amount of "constant" information, a Paper Space template should have, as a minimum, the organization's title block, border (if used), and any other "universal" information - data that will appear on every plotted sheet. The title block and related data should be contained entirely in paper space and drawn to the exact size that it will be when plotted, after making allowances for required margins, etc. For example, a typical plotter will permit a border of something like 23"x34.5" on a 24"x36" "D" size sheet, so a good size for a title block and border in this case would be 23"x34.5".

Other information that may be contained in a template drawing are such things as pre-defined text styles, dimension styles, and linetypes. While many of these can be defined or loaded by AutoCAD "on the fly," putting them in an "organization standard" template file offers somewhat greater assurance that drafters will adhere to standard practices.

Starting a Paper Space drawing is no different starting any drawing, except to be sure that when starting out, the TILEMODE variable is set to 1 (which puts the user "in" Model Space). The drawing is then made in the usual manner, except that the drafter need not worry about such things as "where this sheet starts and ends" or whether what (s)he's working on will fit a sheet when plotted at a particular scale.

As mentioned earlier, an entire project can be done in a single drawing file, if desired, and if the file doesn't grow beyond a manageable size.

When the project has progressed to the point that check plots are needed, it's time to think about creating one or more sheets in Paper Space.

Step 1 - Switch to Paper Space - This is accomplished with the TILEMODE command. When prompted for a TILEMODE value, enter 0 (zero) or Off. This will set AutoCAD to Paper Space mode; the UCSICON, if displayed, will change to a distinctive triangle, and everything drawn in Model Space will disappear. If the drawing was made on a template having a Paper Space title block and/or border, these items should now be available (if not, then ZOOM ALL or ZOOM E[xtents] should bring them into view).

Step 2 - Create a Title Block and/or Border - This needs to be done only if it's not already in the template drawing. Draw them to fit the actual plotted area of the sheet to be used, as outlined earlier.

Step 3 - Create a "Sheet Definition" Layer - This may actually be a "family" of layers, depending on whether some items (such as the viewport borders) may need to have special characteristics (color, linetype, visibility) for the final plot. One workable scheme is to give one layer the same name as the Sheet Number (e.g., C1, C2... for Civil Engineering drawings; A1, A2... for architecturals); and then use sublayers (e.g., C1-TEXT) for other classes of objects. In any case, use the LAYER command in the usual manner; and remember that a separate set of "sheet definition" layers will be needed for each sheet to be defined in the drawing.

Step 4 - Create One or More Viewports - The MVIEW command is used for this. MVIEW can automatically create from one to four viewports, or by clicking and dragging, the user can create rectangular viewports manually. Using MVIEW, create as many viewports as needed for the sheet being designed. The actual number of viewports, along with their relative sizes and aspect ratios aren't all that important at this stage; viewports can be added, erased, stretched and moved as needed as the work progresses.

Step 5 - Enable Viewport Contents - Depending upon the settings of several AutoCAD system variables, each new viewport may be empty, or may contain every object in the Model Space drawing, or somewhere in between. This isn't critical, because the VPLAYER command lets the user control what's visible in each viewport. First, use the MSPACE command to enable a viewport; its outline will change, and the drawing cursor (crosshairs) will be active in only the "current" viewport. Viewports may be selected by clicking inside of any viewport border; typing CTRL-R will move from one viewport to the next sequentially.

Once a viewport is selected and active, use the VPLAYER command (Freeze and Thaw options) to enable just the layers to be visible in that viewport. VPLAYER will accept wildcard characters; VPLAYER F[reeze] * will freeze (make invisible) all layers, while VPLAYER T[haw] * will make all layers visible in the current viewport. The VPLAYER command behaves essentially like the LAYER command, except that it affects only selected viewports.

Step 6 - Set Viewport Scale Factor(s) - The ZOOM command has a special scale format for use with Paper Space viewports. To scale the contents of a viewport to the desired plot scale, type ZOOM, and then the Scale Factor followed by the letters "XP." For example, to set the scale of the current viewport to plot at 1:100 (or 1' = 100'), the command sequence is ZOOM 1/100XP (ZOOM 0.01XP works, too, but usually a rational fraction is easier to remember).

Step 7 - Arrange the View in the Viewport - With the viewport still current, the PAN command may be used to move the visible objects to the desired location in the viewport. If the viewport is too large or too small for the objects (or portions of objects) to eventually appear in the viewport, that will be taken care of in the next step; for now, just PAN the view to an appropriate relationship with one corner (say, upper left) of the viewport. The DVIEW TWIST command may be used to rotate the view if needed. Each viewport will "remember" its zoom scale and rotation, independently from other viewports.

Step 8 - Set Viewport Size - Viewport borders may be moved and stretched to make the viewport exactly contain the desired Model Space objects. First, use the PSPACE command to return to Paper Space (the cursor is now active over the entire drawing area). Next, use the STRETCH command to size the viewport; unlike other objects, you need only select one corner of a viewport with the crossing box to begin stretching.

Step 9 - Arrange Viewports on the Sheet - Once they are enabled, scaled, and sized, viewports may be moved to any location on the sheet. Use the MOVE command, select the viewport(s) to be moved, and drag them to their desired location(s).

Step 10 - Finishing Touches - At this stage, the current sheet should consist of a title block and/or border, along with one or more correctly arranged viewports. All that's left to be done is to add the "variable" notation that's specific to this sheet: View Titles, if appropriate; Sheet Number; Sheet Description; and any other information which will appear on this sheet, but not necessarily on others.

In some cases the viewport borders may be left visible as "frames" for the various viewports. However, any or all of them may be made invisible without affecting the viewports' contents; to make viewport borders invisible, simply turn Off or Freeze the Layer in which the viewport boundary was drawn (Freezing is preferable, since it eliminates the borders from consideration by AutoCAD's Extents variable).

The process described above may be repeated for any number of Sheet Definitions in a given drawing. Where multiple sheets exist in a drawing, it is important that a set of Sheet Definition layers exist for each Sheet. In this manner, Freezing and Thawing sets of Sheet Definition layers, and enabling or disabling the viewports contained therein, provides the means for selecting any single sheet to be displayed or plotted.

Before creating additional sheets, the contents of the most recently created one must be cleared from the working area. The viewports need to be disabled (turned off), and their borders and other "variable" objects in the sheet made invisible by freezing their respective layers.

First, disable viewports using the MVIEW command: MVIEW OFF ALL. Note that a viewport's borders must be visible in order for the MVIEW OFF (or ON) command to be effective. Next, hide all of the sheet-specific information by freezing the Sheet Definition layer(s); for sheet C1, for example, use -LA[yer] F[reeze] C1* - the wildcard C1* acts on all layers with names starting with "C1."

Just two AutoCAD commands are required to display a sheet once it has been defined: LAYER (Freeze and Thaw options), and MVIEW (On and Off options). The following steps assume that the user is in Paper Space (TILEMODE = 0).

First, to ensure that all viewports are available:

-LA[yer] T[haw] * (thaw all layers).

Next, turn off all viewports:

MVIEW OFF ALL

Then, freeze all Sheet Definition layers except those of the sheet to be displayed:

-LA[yer] F[reeze] C#* (freezes all layers starting with C and a digit).
-LA[yer] T[haw] C2* (thaws all layers for sheet C2).

Now, turn on Sheet C2's viewports:

MVIEW ON ALL (acts only on visible viewport borders).

And, finally (if desired) hide the viewport borders:

-LA[yer] F[reeze] C2 (freeze only layer C2).

Like strong drugs, most users will find that the above procedures are best "for occasional use only." Fortunately, AutoCAD is a programmable application, and once a set of layering standards has been developed and firmly adopted, all of the processes described above are easily committed to one or another of AutoCAD's several programming languages.

SHOW.LSP, a shareware package available from Tee Square Graphics, contains a solution to both Sheet Definition and Sheet Selection and Display using AutoLISP and Dialog Control Language (DCL). Four files are required to run the demonstration: PSDEMO.DWG, SHOW.LSP, ALPHANUM.SLB, and ARROWS.SLD.

To run the Demonstration, copy the files to the main AutoCAD directory (folder), then OPEN the drawing PSDEMO, and load SHOW.LSP (LOAD "SHOW"). The SHOW command is used to set up and display any of four sheet definitions contained in PSDEMO, and the PLSHEET command may be used to launch a Sheet Definition routine.

PLSHEET permits up to 16 viewports to be defined in a single sheet, and will prompt the user for the layers to be included in each viewport, along with the scale and view rotation.

"Paper Space Tutorial" Copyright (c) 1998 Tee Square Graphics. All rights reserved.
Permission to copy, distribute or reproduce this article may be obtained via email to cadman@turvill.com.

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