In either AutoCAD Civil 3D or Map 3D, we often find ourselves designing a set of plans or planning a utility layout with aerial photography in the background. Most designers will do most of their drafting with the image either unloaded or turn off the layer it is on as this reduces the amount of processing time for simple actions such as panning and zooming. There is a small “flaw” with the default settings that many people have run into with an aerial or any background image,which I’ll be getting to shortly.

One of the most used commands in AutoCAD is UNDO (Ctrl+Z). However, that isn’t always the most efficient or useful tool especially if you are selecting items for a command. One tool that I would equate to UNDO is utilizing Shift+Left Click to deselect drawing entities in your selection set. Sometimes this is necessary because you’ve accidentally picked an unintended object, but it can also be utilized when it is just easier to select a large group of  items and deselect a few.

Herein lies the problem, though. By default, in Civil and Map 3D, if there is an aerial or background image loaded, Shift+Left Click will actually select the image instead of deselecting the object you are targeting, even if that image is on an “off” layer. This was an intentional feature for AutoCAD Civil 3D and Map 3D, as the only other way to select an image is to zoom out and pick the image frame. This can be very cumbersome when dealing with 300 MB aerial photography files that need to process everytime you zoom or pan significantly. Luckily, whether you like this feature or not Autodesk has given you the choice of setting your preference.

That choice isn’t inherently easy to find, though. In previous releases (2006, ’07, ’08, and ’09 to my knowledge) you could enter the command IOPTIONS and edit the settings within the mouse action options. However, that changed with the 2010 release of AutoCAD Civil 3D and Map 3D. Now, the command has changed to MAPIOPTIONS and the dialog is a little different.