Point of Beginning

Surveying GIS: Footprints in time.

February 28, 2003


ArcView 3.x symbol palette.
We as a society seem to have a propensity, if not an obsession, with making things (and people) fit into groups or niches. Surveyors, rugged individualism aside, don’t seem to be that much different. Most of us fall in with one of the two main camps: “location, location, location” or “perception is everything.”

The divide, in my view, has rarely been as well defined as it was in the November 2002 issue of POB in Milton Denny’s article “The Business Side: Planning Ahead.” Denny describes this divide as the implicit gulf between surveyors (location) and engineers (perception). But it’s more complicated than that. At times we seem to forget that first and foremost, surveying is a people-oriented business. Ergo, part of a surveyor’s training needs to incorporate interaction with people. It is important to our clients where we place their property lines and where and how we set out the improvements. Our clients tend to take those things very personally, and we need to understand that.

Another thing to understand is that we got here by following the footsteps of those before us in more ways than one. So, let us think about and consider the “footprints” we are leaving for others to follow. And to leave useful footprints, looking forward is a solid prerequisite. But a quick glance back often serves as an aid in planning that route ahead.

While I was taking a quick glance back, I came across this quote from an article in the August-September 1986 issue of POB:

“What is CAD? Computer-Aided Drafting (CAD) has become the trendy buzzword of the computer industry. It encompasses a wide range of graphics applications software, including circuit board layout, mechanical drafting, architectural drafting, general purpose graphics packages, and civil/ surveying drafting, ranging in price from under $1,000 to well over $500,000. Choosing the wrong CAD software can often lead to CAB (Computer-Aided Bankruptcy).”

I think most of us would agree that CAD is no longer a “trendy buzzword” to surveyors. It is nearly as indispensable as any other component of the modern surveyor’s toolbox. I began this odyssey attempting to answer the arguably more difficult question: What is GIS? GIS is not unlike other innovations that have impacted the scope of the surveyor’s world. One must invest to get the benefit of dividends. But one must invest wisely. The tableau that follows is designed to illustrate some of the differences between CAD and GIS software packages utilizing feature labeling as a theme.

An ArcView 3 table created from an AutoCAD drawing.

Labeling CAD Drawings in ArcView

When a CAD drawing is imported into ESRI’s ArcView 3.x, how the attribute data appears in the table that ArcView creates is a function of how the layers in the CAD drawing are constructed. There are other very important points to consider. When ArcView 3.x imports numeric values from a CAD file, they are read as integers and assigned four decimal places.

To add the labels to the View, choose “Auto-Label” from the “Theme” menu. Locate the field you wish to label from the drop-down menu in the dialog box. Use the check boxes and “radio” buttons to select placement, then click “OK.” The labels that appear are generated by the default symbol set. If you want to change the text size or color go back to the “Theme” menu and choose “Remove Labels.” The default values for symbols can be displayed by choosing the “Graphics” menu and clicking on “Text and Label Defaults.”



To change the properties of the labels you wish to display from the Window menu, choose “Show Symbol Window.” This brings up the font palette.



Typical CAD drawing of topographic contours displayed in Autodesk Map 5.
Click on the “ABC” (font) button. The current text size is displayed. Choose a new text size. Then click on the “Paintbrush” and select _a color. Then repeat the “Auto-Label” command.



Labeled contours in ArcView 3.
There are two important things to remember about labeling in ArcView 3.x. One, ArcView scales the labels in the view by default. They appear larger when zoomed in on. The user can change this to a static size by unchecking the “Scale Labels” box in the Theme Properties dialog. Two, labeling from the tables will begin to add to the size of your .apr file significantly. ArcGIS version 8 handles the situation differently. It reads everything from the data frame. There is no CAD Reader Extension to worry about. Just click the “+” on the GUI and navigate to your CAD file.



ArcGIS v 8 reads everything from the data frame, allowing the user to simply click on the + sign on the GUI and navigate to the CAD file.
To display the table ArcMap created from the layers in the AutoCAD drawing file, right click on the layer in the data frame. (Note that in this example only the integer value for the contour elevation is read into the table.) Close the table.

To label the features in the Map View, right click on the layer in the data frame. Select “Properties.” This brings up the dialog box for the properties in the layers.



View of table in ArcMap showing elevation field.

Image 7

In this dialog the user gets a good feel for the differences between ArcView 8.x and ArcView 3.x architecture. The user can change and manipulate nearly all the layer properties from this dialog. For now we will focus on the “Labels” tab. Choose the field to label. Choose the label location. “Symbol” here means text style. It offers a variety of fonts and colors. After you make a selection, simply click “Apply.” Click “OK” and right click the layer on the data frame. Click “Label Features” and view the results.



ArcMap properties dialog box.
We will explore some of those other tabs next month.