Graphics Programs Reference
In-Depth Information
6.
At the Specify scale factor or [Copy/Reference]: prompt, enter
R
↵ to use the
Reference option.
7.
At the Specify reference length <1>: prompt, type
@
↵. This tells AutoCAD that you
want to use the last point selected as one end of the reference length. After you enter the
@ symbol, you'll see a rubber-banding line emanating from the X.
8.
At the Specify second point: prompt, click the X at the lower-right corner of the image.
9.
At the Specify new length or [Points]: prompt, enter
44´
↵. Metric users should enter
1341
↵. The image enlarges. Remember that this reference line is 44´ or 1341 cm in length.
The image is now scaled properly for the plan it portrays. You can proceed to trace over the
image. You can also place the image on its own layer and turn it off from time to time to check
your trace work. Even if you don't trace the scanned floor plan line for line, you can read the
dimensions of the plan from your computer monitor instead of having to go back and forth
between measuring the paper image and drawing the plan on the computer.
Controlling Object Visibility and Overlap with Raster Images
With the introduction of raster-image support, AutoCAD inherited a problem that's fairly com-
mon to programs that use such images: Raster images obscure other objects that were placed
previously. The image you imported in the previous exercise, for example, obscures the line you
drew when you first opened the file. In most cases this overlap isn't a problem, but in some situ-
ations you'll want AutoCAD vector objects to overlap an imported raster image. An example is a
civil-engineering drawing showing an AutoCAD drawing of a new road superimposed over an
aerial view of the location for the road.
Paint and page-layout programs usually offer a “to front/to back” tool to control the overlap
of objects and images. AutoCAD offers the Draworder command. Here's how it works:
1.
Press
Z
↵
E
↵ to get an overall view of the image.
2.
Click on the red colored line you drew when you first created the file. You can select other
objects if you wish.
3.
Right-click and select Draw Order
Bring Above Objects from the shortcut menu.
4.
At the Select reference objects: prompt, click the edge of the raster image of the
utility room, and then press ↵.
The drawing regenerates and the entire line appears, no longer obscured by the raster image.
MASKING AN AREA OF AN IMAGE
You can mask out areas of an imported raster image by creating a solid hatch area and using the
Draworder command to place the solid hatch on top of the raster image. Such masks can be help-
ful as backgrounds for text that must be placed over a raster image. You can also use the Wipeout
command (choose Draw
Wipeout from the menu bar) to mask areas of a drawing.
