Zoom and Pan with Glass and Hand

Moving your viewpoint in to get a closer view of your drawing data is called zooming in; moving your viewpoint back to get a more expansive view is called zooming out. Moving your viewpoint to another part of your drawing without zooming in or out is called panning.

Changing your viewing position lets you do detailed work on tiny objects and then zoom out and move around rooms, houses, or neighborhoods from an Olympian perspective. Early versions of AutoCAD included a sample drawing of our solar system, drawn to scale with kilometers as units, which proved this. If you zoomed all the way out, you could see Pluto's orbit (yes, kids, Pluto was a planet back then), and you could zoom in close enough to Earth's moon to read the inscription on the plaque left by the Apollo 11 astronauts!

Panning means changing your viewing position without changing the magnification of the view. If you zoom in enough that some of your drawing no longer shows up on-screen, you're going to want to pan around — move left, right, up, and down in your drawing — without zooming in and out. AutoCAD makes panning easy with scroll bars and realtime panning. And in case you're wondering what realtime panning might be (as opposed to pretendtime panning, maybe?), it simply means you can see the objects moving around the screen as you drag the mouse up and down or back and forth. (Of course, it's your viewpoint that's moving, not the objects!)

Both panning and zooming change the view — the current location and magnification of the AutoCAD depiction of your drawing. Each time you zoom or pan, you establish a new view. You can give a name to a specific view to make returning to that view easy, as I demonstrate in the section “A View by Any Other Name …,” later in this chapter.

You'll get a better sense of panning and zooming around a drawing if you actually have a drawing to look at. Draw some objects on the screen, open one of your own existing drawings, or launch one of AutoCAD's sample drawings. (If you haven't done so already, you can download the sample files from www.autodesk.com/autocad-samples; the AutoCAD LT sample files are also online now, at www.autodesk.com/autocadlt-samples.)

Navigating your drawing

You may think that AutoCAD is all about drawing, and maybe, occasionally, even about erasing. In that case, it may surprise you to learn that two of the most frequently used commands in all of AutoCAD are PAN and ZOOM. These commands and a few others can be found on an interface component called the Navigation bar.

The Navigation bar is linked by default to another interface component named the ViewCube. (AutoCAD LT users get the Navigation bar, but not the ViewCube.) Figure 12-1 shows the upper-right corner of the AutoCAD window with the ViewCube and Navigation bar in their default locations.

Figure 12-1: Belly up to the Navigation bar.

I fill you in on the ViewCube in Chapter 21, since it's a more useful tool in three dimensions than in two. I also cover the SteeringWheels and ShowMotion commands (the latter is not present in AutoCAD LT) in Part V of this book.

Controlling your cube

Apart from the big chunk of screen space the ViewCube and Navigation bar occupy, the cube itself has some disconcerting behaviors. If you click the Home button, for example, you automatically switch to a preset 3D isometric view — not that helpful if you're doing a 2D drawing.

I think the cube-bar combo is worthwhile when you're doing 3D modeling, but more intrusive than useful for 2D drafting. Luckily, AutoCAD offers quite a bit of control over both the ViewCube and the Navigation bar. You can turn off the navigation buttons you don't use, and you can turn off the ViewCube itself, either for the drawing session or permanently.

• To turn off navigation buttons: Open the Navigation bar's menu by clicking the down arrow at its bottom-right corner (refer to Figure 12-1) and unchecking SteeringWheels, Orbit, and ShowMotion.
• To turn off the ViewCube in the current viewport: Go to the View tab's Windows panel, click User Interface, and uncheck ViewCube. Reverse the procedure to turn it on again.
• To turn off the ViewCube permanently: Open the Options dialog box, and select the 3D Modeling tab. In the Display Tools In Viewport area, uncheck 2D Wireframe Visual Style and All Other Visual Styles under Display The ViewCube.

In addition to the Navigation bar, the Navigate and Navigate 2D panels of the Ribbon's View tab contains a Pan button and a drop-down set of Zoom tool buttons (in my opinion, not a very convenient location for such frequently used commands!).

AutoCAD offers 11 different ways of zooming around in your drawing; I explain the most important ones in the next section. The following steps describe how to use AutoCAD's Zoom and Pan Realtime feature, which is easy to operate and provides a lot of flexibility:

1. Click the lower part of the Zoom split button on the Navigation bar and choose Zoom Realtime from the menu.

   The Realtime option of the ZOOM command starts. The crosshairs change to a magnifying glass, and AutoCAD prompts you at the command line:

   Specify corner of window, enter a scale factor (nX or nXP), or [All/Center/
              Dynamic/Extents/Previous/Scale/Window/Object] <real time>:
   Press ESC or ENTER to exit, or right-click to display shortcut menu.

2. Move the magnifying glass cursor near the middle of the screen, press and hold down the left mouse button, and drag the cursor up and down until the objects you want to see almost fill the screen.

   Dragging up increases the zoom magnification, and dragging down decreases it.

3. Right-click in the drawing area and choose Pan from the menu that appears (as shown in Figure 12-2).

   

   Figure 12-2: The Zoom/Pan Realtime right-click menu.

   Because AutoCAD LT doesn't do 3D, there's no 3D Orbit choice on LT's right-click menu. The magnifying glass cursor changes to a hand.

4. Click and drag to pan the drawing in any direction.

   You can use the right-click menu to toggle between Zoom and Pan as many times as you like. If you get lost in your drawing, choose Zoom Original or Zoom Extents to return to a more familiar view.

5. Right-click in the drawing area and choose Exit.

   The Zoom or Pan Realtime cursor returns to the normal AutoCAD crosshairs.

In the preceding example, you started with zooming and ended with panning. You also have the option of doing the reverse: Click the Pan button on the Navigation bar, and after you've panned, use the right-click menu to switch to zooming. However you start it, the important thing to realize is that Zoom and Pan Realtime is a single AutoCAD function. At any time, you can switch between panning and zooming (or switch to a related function, such as Zoom Window) by using the right-click menu.

• To pan: Hold down the scroll wheel or the middle button as you move the mouse.
• To zoom in and out: Roll the scroll wheel forward and backward.
• To zoom to the extents of your drawing: Double-click the scroll wheel or the middle button.

Realtime zooming and panning is the easiest, most interactive way to get around in your drawings. In some situations, though, this method is less efficient or precise than the old-fashioned methods, the most important of which I describe in the next section.

Time to zoom

Realtime zooming is good as far as it goes, but you get much more control over the display if you use some of ZOOM's alternative methods. Because zooming is such a frequent activity in AutoCAD, it's worth knowing some of those alternative ways of doing it.

In addition to the Navigation bar button I describe above, you'll find tool buttons for all the ZOOM options on the View tab's Navigate 2D panel (this panel is called, simply, Navigate in AutoCAD's 3D Modeling workspace). The magnifying-glass button has a menu — click the down arrow beside the magnifying glass, and a menu with the other options opens (see Figure 12-3).

Figure 12-3: A menu for magnifying.

The ZOOM command has 11 different options, the most important of which are the following:

• 
  Extents and All: Zoom Extents (the button with the four-headed arrow and the magnifying glass) zooms out just far enough to show all the objects in the current drawing. Zoom All (the button showing the sheet with the folded-over corner) does the same thing, unless the drawing's limits are larger than the extents, in which case, Zoom All zooms to show the entire rectangular area defined by the limits. These two options are especially useful when you zoom in too small or pan off into empty space and want to see your entire drawing again.

  It's a good idea to Zoom All or Zoom Extents and then save the drawing before you close it. By performing these steps, you ensure the following:

  • The next person who opens the drawing — whether it's you or someone else — can see the full drawing as soon as they start working.
  • If you've accidentally copied some objects way beyond where they should be, Zoom All or Extents will make them show up so you can delete them.
  • The drawing preview that appears in the Select File dialog box displays the full drawing, instead of just a tiny, unidentifiable corner of it.
• Window: This option is great for zooming in quickly and precisely. It zooms to a section of your drawing that you specify by clicking two points. The two points define the diagonal of a window around the area you want to look at.

  Note that the ZOOM command's Window option is not a click-and-drag operation — unlike in some other Windows programs and, confusingly, unlike in the Zoom/Pan Realtime Zoom Window option. With the ZOOM command's Window option, you click one corner, release the mouse button, and then click the other corner.

• Realtime: Realtime zooming, the technique described previously, enables you to zoom in and out by starting a realtime zoom and then dragging the magnifying glass cursor up (to zoom in) or down (to zoom out).
• Previous: This option undoes the last zoom and/or pan sequence, taking you back to where you started.
• Object: This option zooms in close enough to show selected objects as large as they can be displayed on-screen. Using ZOOM Object is like putting the selected objects under AutoCAD's microscope.

Some of the zoom options take some getting used to. I recommend that you use realtime zoom and pan for most of your zooming and panning. Supplement it with Zoom Window to move quickly into a precise area, Zoom Previous to go back in zoom/pan time, and Zoom All or Zoom Extents to view your whole drawing.