Autodesk AutoCAD software is firmly embedded in the engineering culture. However, with a new version of AutoCAD out every year (or even more frequently), it can be difficult to keep up. For surveyors who are forced to make giant leaps across several years of upgrades or from AutoCAD Land Desktop to AutoCAD Civil 3D, the task can seem incredibly daunting. The following five tips, learned through extensive hands-on experience, can make AutoCAD Civil 3D easier to use.
1. Remember That Points Are 3D Objects. Unlike Land Desktop, Civil 3D considers points to be 3D objects, even if they are inserted in the drawing in 2D (flattened to elevation zero). This can cause problems when manipulating the points. For example, when moving points in a horizontal datum translation, the elevations can be affected if the points are moved using an object snap and the objects to which the points are snapped are at different elevations. The point elevations for all the moved points will change by the elevation difference of the two object snaps. The key to avoiding this problem is either to make sure that the objects used for moving the points are at the same elevation or to correct the change with a vertical datum shift.
Another frequently encountered problem is that the software automatically scales the points in the vertical dimension when converting between grid and ground. This may not be an issue for lower elevations, but the difference can be significant for high elevations. The fix for this problem involves four steps. First, create a new point import/export style that only contains the point number and the elevation. Second, before scaling to or from grid, export the points using this style into a temporary file. Third, scale the points as usual. (The points will now be at the correct horizontal position but the wrong elevation, with the amount varying by the scale factor times the original elevation of each point.) The final step is to re-import the points using the new style, which is only the point number and elevation. When the software asks what to do about the already used point numbers, select “overwrite.” The software won’t move the points horizontally, but it will take the imported elevations and assign them to each point. The points will then be at the correct horizontal and vertical positions.
2. Use the Layer Control Tools. Users who wish to manipulate all the objects on one or more layers without altering objects on other layers can use the LAYISO command. This command isolates selected layers and saves the previous layer state, which can be reverted to using the LAYUNISO command.
Here is a real-world land surveying application for this command. After completing a preliminary design for a new subdivision, the client reviews the drawing and requests a change to all the proposed lots on one block. Erasing the previously proposed lot lines would be foolish, since the client could easily decide to revert to the previous design. Instead, the internal proposed lot lines for the block in question could be placed on another layer and “frozen” for future use by using the LAYISO command and selecting the lot line layer. The internal lot lines for that block can then be selected using a crossing selection, without any other drawing objects interfering with the selection. Once the lot lines are selected, they can be moved to the “to be frozen” layer using the layer control toolbar, the “properties” dialog or the –CH keyboard command. The user can then return to the previous layer state using the LAYUNISO command and continue with the task at hand.
If the objects to be isolated are on a block with a nested layer, turning off the nested layer has the undesirable side effect of making desired objects invisible. In a large drawing with hundreds of layers (such as an engineering drawing with several external references to other AutoCAD drawings, called “X-refs”), the user has little chance of finding the correct layer to turn back on to see the desired objects. In this case, before activating the LAYISO command, the user should first “explode” the desired block and note the names of the nested layers by using the “list” command. Once the nested layers are noted, the user can then undo twice (once for the list command and once for the explode command), and run LAYISO as usual. The nested layers will be turned off as before, but now the user can easily turn the previously noted layers back on. The LAYUNISO command will be unaffected by the intermediate layer manipulations.
It should also be mentioned that these commands (or any others) may be shortened or changed to a more memorable keyboard shortcut by placing them in the acad.pgp file. (For more information on editing the acad.pgp file, search “edit aliases” in the AutoCAD help menu.)
3. Save Time by Creating Drawing Templates. Land Desktop users may also be surprised to find that most customizations, such as line/curve label styles and point label styles, are a part of each drawing in Civil 3D rather than part of the user’s customization file. As a result, a drawing template that contains all the custom drawing objects should be used within each company or department. While this practice may seem a bit cumbersome at first, creating several different drawing templates can actually save quite a bit of time spent searching through custom object lists for the one style needed. For example, a template for a boundary survey would not need any topographic styles such as contour and surface modeling styles. If after starting a project it becomes necessary to include styles that are contained in another template, they can easily be added by creating an empty drawing from that template and inserting it as a block. All the layers, styles and other customizations from that template will now be in the drawing, and any that are not needed can be purged out of the drawing at any time.
4. Customize Your Object Snaps. Many users have trouble with the object snap toolbar because the buttons on the object snap (OSNAP) toolbar are too small or too similar. The most often used OSNAPs can instead be set as active in the OSNAP dialog (type “OS” to see this dialog) and can be toggled on and off using the F3 key. Any other needed OSNAPs can be accessed from the center mouse button. When accessed in this way, the names of the OSNAPs are spelled out instead of being depicted as symbols.
There is a tradeoff in the loss of the pan function from the center mouse button. However, this limitation can be overcome in three ways. First, when not in an active command, the pan function can be activated by typing the letter “P.” Second, the pan function can be activated from the standard toolbar. And third, the user can simply dispense with the pan function and navigate the drawing using the scroll wheel to zoom in and out. By zooming out until they can see the desired location in the drawing and then zooming in on that point until the desired detail is revealed, many users find they can move about in the drawing more efficiently than by using the pan command. The center mouse button can be toggled to the OSNAP control by typing MBUTTONPAN and changing the setting to “0.”
5. Use More Monitors. The associative and interactive nature of Civil 3D means that considerable time is spent manipulating objects within dialog boxes, such as “toolspace” and “properties.” These dialog boxes take up huge amounts of monitor real estate, to the point that some users working on one monitor find that the space left for the actual drawing is insufficient. Those with only one monitor output on an existing system have little recourse, but the possibility of adding a second monitor should be seriously considered when contemplating an upgrade or purchasing a new system. Quite simply, more monitors are better.
These are just a few of the many tips that can make working with AutoCAD Civil 3D easier. Additional tips can be found through the various AutoCAD user forums or the help menu within the software. I also can’t say enough about having a good textbook on AutoCAD--anything you need to know about is in there and can be found through the index.
With a little research, patience and practice, you should soon find yourself navigating easily through Civil 3D. Good luck!