Advanced Topics

Autocad's Inquiry Tools

AutoCAD has many tools to help you as a designer. Some of these you may have already used. The properties command gives you a lot of information about an object you have selected and allows you change most of them. AutoCAD also has some commands used specifically for pulling information from objects. Most of these commands can be accessed from the Tools pull-down menu. Here is a list of those commands (click on the icon for more information) :

COMMAND KEYBOARD ICON DESCRIPTION Distance DI Distance Measures the distance and angle between two points Area AREA Area Calculates the area and perimeter of objects or of defined areas. Mass Properties MASSPROP Mass Properties Calculates and displays the mass properties of regions or solids. List LI List Displays database information for selected objects. ID ID ID Point Displays the coordinate values of a location.

The first one, DISTANCE (DI), is quite straight forward. It allows you to select two points on the screen and AutoCAD will tell you the total distance as well as the changes in X,Y & Z. AREA is a command that can be very useful. This can used to calculate square footage for floors, property lots, or even something like sheet metal parts. To use this command, you can type in AREA and see this on your command line:

Command: area <First point>/Object/Add/Subtract: O Select objects:<SELECT AN OBJECT> Area = 56.7498, Perimeter = 30.6775

The default option is to pick a point on the screen. This allows you to select the four corners of a room to find the total area in square drawing units (usually inches). You can pick as many points as you need and then press enter when you're done. AutoCAD returns the area and the perimeter length. If you select the next option (object), you can select a circle, rectangle, polyline or some other closed object. You also have the option of adding to or subtracting from the initial area. You may need to find the carpeting area of a room, but exclude where you have tile. Or you may need to add several rooms together. MASS PROPERTIES is an option for finding information about 3D solid objects. You can find out the total volume and from there calculate the weight based on volume. AutoCAD also figures out some important engineering figures for you such as the center of gravity for an object. This listing shows you all the information you can get from MASSPROP:

Command: MASSPROP Select objects: 1 found Select objects: ---------------- SOLIDS ---------------- Mass: 150.0000 Volume: 150.0000 Bounding box: X: 11.7974 -- 16.7974 Y: 2.7812 -- 7.7812 Z: 0.0000 -- 6.0000 Centroid: X: 14.2974 Y: 5.2812 Z: 3.0000 Moments of inertia: X: 6296.1089 Y: 32774.6574 Z: 35470.7663 Products of inertia: XY: 11326.0088 YZ: 2376.5252 ZX: 6433.8101 Radii of gyration: X: 6.4787 Y: 14.7817 Z: 15.3776 Press ENTER to continue: Principal moments and X-Y-Z directions about centroid: I: 762.5000 along [1.0000 0.0000 0.0000] J: 762.5000 along [0.0000 1.0000 0.0000] K: 625.0000 along [0.0000 0.0000 1.0000] Write to a file ? <N>:

This is a lot of information, so AutoCAD gives you the option of saving it to a file after it is displayed.

LIST is an inquiry that gives you some basic information about a command. This is usually the information that AutoCAD needs to know about it to keep track of it in its database. Here is a listing of a line:

LIST 1 found LINE Layer: 0 Space: Model space Handle = 22 from point, X= 6.2991 Y= 5.0491 Z= 0.0000 to point, X= 6.2035 Y= 2.2798 Z= 0.0000 Length = 2.7709, Angle in XY Plane = 268 Delta X = -0.0956, Delta Y = -2.7692, Delta Z = 0.0000

Here are the properties for the same line:

Notice that you can get the same information, but also have the option of changing anything that you need to. After List, the next option is ID POINT. This allows you to select anywhere on the screen and have AutoCAD return the X,Y&Z co-ordinates for that point. Here is a listing of ID POINT:

Command: ID Specify point: <SELECT POINT> X = 155'-2 1/2" Y = 48'-9 3/16" Z = 0'-0"

(You can also get this information by selecting a grip and looking at the status bar.)

OTHER INQUIRY TOOLS: Time Displays the date and time statistics of a drawing. Type TIME. Status Displays drawing statistics, modes, and extents. Type STATUS. Set Variable Lists or changes the values of system variables. Type SETVAR. TIME and STATUS are two inquiries that give you information about the system, as opposed to objects.

Here is a listing of TIME:

Command: time Current time: Tuesday, May 16, 2000 at 11:55:09:600 AM Times for this drawing: Created: Tuesday, May 16, 2000 at 11:21:43:720 AM Last updated: Tuesday, May 16, 2000 at 11:21:43:720 AM Total editing time: 0 days 00:33:25.880 Elapsed timer (on): 0 days 00:33:25.880 Next automatic save in: 0 days 00:03:45.120 Display/ON/OFF/Reset:

You can see the current date, when you last saved and when AutoCAD will do its next automatic save.

Here is a listing of STATUS:

Command: status 120 objects in Drawing1.dwg Model space limits are X: 0.0000 Y: 0.0000 (Off) X: 12.0000 Y: 9.0000 Model space uses X: -4.1963 Y: -0.2930 **Over X: 52.2702 Y: 34.7170 **Over Display shows X: -9.5333 Y: -7.2543 X: 68.2812 Y: 37.6074 Insertion base is X: 0.0000 Y: 0.0000 Z: 0.0000 Snap resolution is X: 0.5000 Y: 0.5000 Grid spacing is X: 0.5000 Y: 0.5000 Current space: Model space Current layout: Model Current layer: "TEXT" Current color: BYLAYER -- 3 (green) Current linetype: BYLAYER -- "Continuous" Current lineweight: BYLAYER Current elevation: 0.0000 thickness: 0.0000 Fill on Grid off Ortho off Qtext off Snap off Tablet off Object snap modes: Center, Endpoint, Intersection, Midpoint, Quadrant, Extension Free dwg disk (C:) space: 2797.3 MBytes Free temp disk (C:) space: 2797.3 MBytes Free physical memory: 13.6 Mbytes (out of 509.8M). Free swap file space: 752.0 Mbytes (out of 1246.3M).

As you can see, there is a lot of information here, not only about your drawing, but about the computer you are working on. The last inquiry, SET VARIABLE (SETVAR), allows you to change any system variables, or if you like AutoCAD will list them for you. The details of this command are not covered in this lesson. You must be VERY careful when working with system variables.