Creating Dimensions in Model Space and Paper Space


You can draw dimensions in layouts (created in paper space) and in model space. However, if the geometry you’re dimensioning is in model space, draw dimensions in model space because AutoCAD places the definition points in the space where the geometry is drawn and you can edit them together.
If you draw a dimension in a layout that describes geometry in your model, the layout dimension does not change when you use editing commands or change the magnification of the display in the model space viewport. The location of the layout dimensions also stays the same when you change a view from a layout to model space.

If you dimension in layouts, you can set the linear dimension scale on the Primary Units tab of the Dimension Style dialog box (DIMLFAC system variable) to less than zero, the distance measured is multiplied by the scale’s absolute value. If you dimension in model space, the value of 1.0 is used even if DIMLFAC is less than zero. In layouts, AutoCAD computes a value for DIMLFAC if you change the variable from the DIM prompt and select the Viewport option. To do this, enter DIM at the command prompt, then enter DIMLFAC. Select the Viewport option, and then select the viewport you want to scale. AutoCAD calculates the scaling of model space to layouts and assigns the negative of this value to DIMLFAC.

Using the DIMLFAC system variable, you can adjust the dimension length scale factor to the zoom scale factor of a model space viewport automatically. This is possible only from a layout, and you must enter DIMLFAC from the DIM command. This scaling method does not work for ordinate dimensions.

To set dimension scale in a layout

  1. Choose a layout tab.
  2. At the Command prompt, enter dimlfac.
  3. At the prompt, enter a new dimension scale.

To dimension in floating viewports

  1. Set the current layer to one that is visible only in the chosen viewport.
  2. From the Dimension menu, choose Style.
  3. In the Dimension Style Manager, select New, Modify, or Override, depending on whether you are creating a new dimension style or modifying or overriding an existing one.402
  4. In the Dimension Style Manager, choose the Fit tab.
  5. Under Scale for Dimension Features, select Dimension to Layout.
  6. Dimension the object.
  7. NOTE Before you add dimensions, be sure to zoom to the correct scale. See “Scaling Views Relative to Paper Space.”

AutoCAD computes a scale factor based on the scaling between the layout and the current model space viewport. You may prefer to work in model space but use the dimensioning capabilities of layouts. The following procedures explain how to do this.

To dimension in model space for layouts in paper space

  1. From the Dimension menu, choose Style.
  2. In the Dimension Style Manager, select New or Modify, depending on whether you are creating a new style or modifying an existing one.
  3. In the Dimension Style Manager, choose the Fit tab.
  4. Under Overall Scale, enter a value for the overall scale.
  5. Choose OK to exit each dialog box.
  6. Add the dimensions to the drawing using the scale you defined.
  7. When you’re ready to lay out or plot your drawing, continue with the following procedure.

To complete the dimensions in layouts

  1. Choose a layout tab.
  2. Switch to a model space viewport.
  3. For more information about model space viewports, see “Creating Nonrectangular Viewports” in chapter 15, “Creating a Layout to Plot.”

  4. From the Dimension menu, choose Style.
  5. In the Dimension Style Manager, select New or Modify, depending on whether you are creating a new style or modifying an existing one.
  6. In the Dimension Style Manager, choose the Fit tab.
  7. Under Scale for Dimension Features, select Dimension to Layout.
  8. Choose OK to close each dialog box.
  9. From the Dimension menu, choose Update, and then select the dimensions that apply to your current view.

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