Building Bridges between Platforms

7 Dec, 2013 By: Cyrena Respini-Irwin

User Profile: For civil engineering firm IDS to function, data must move smoothly between GIS and CAD — and Amanda Nunley Menard is the person who gets it there.

Amanda Nunley Menard's job bridges two worlds: CAD and geographic information systems (GIS). She is the GIS manager at IDS Engineering Group, a Texas-based firm that provides infrastructure design services for public and private clients. As such, Menard produces maps, designs and maintains databases, and builds web mapping applications. She also moves masses of data between the Esri ArcMap GIS and AutoCAD and Bentley Systems' MicroStation CAD platforms — and vice versa — giving her coworkers the tools that are essential to their work.

Cadalyst: How did you become interested in GIS?

Menard: When I started my career, I had the intention of becoming a computer programmer. At the same time, I loved science, and I'm an environmentalist at heart. While I was pursuing my bachelor’s degree in Computer Science at Texas A&M University, I learned about GIS, and it seemed like a perfect way to blend what I was good at with what I was passionate about. When I changed my major to Geography, I had my first formal training in GIS — and I have loved it ever since.

What role does CAD play in your work?

I’d consider myself an advanced GIS user, but I'm still a pretty novice AutoCAD/[AutoCAD Map 3D] user. Although I rarely work directly in AutoCAD, I spend a large amount of time converting data between CAD and GIS; working with coordinate systems, scaling issues, and data translation.

I never received any formal training in AutoCAD. Instead, I started experimenting in AutoCAD Map 3D a few years ago, out of necessity: Every day we are asked to show a CAD drawing as a layer in one of our GIS maps, and no matter how great that CAD drawing is, it rarely displays the way you’d expect in GIS.

While working with some great designers at my company, I learned how to make minor edits, work with layers, and — one of my favorites — explode all those blocks! Yes, I know you CAD guys are all cringing, but ArcMap just hates blocks; they don't display correctly.

The most common reason that I use CAD is to scale drawings from surface (ground or flat) coordinates to grid (curved) coordinates. And sometimes doing basic things, such as turning off or freezing CAD layers, is just easier in CAD than ArcMap.

What kinds of data do you manipulate in AutoCAD?

I most commonly work with land plans, survey data, or infrastructure utility lines. I wish I could say that the process is always easy, but each dataset is unique.

One challenge that I run into frequently is lining up drawings created in assumed coordinate systems with GIS data in geographic coordinates systems. To an engineering company, accuracy and precision are critical in this process; shifting a drawing around in GIS could really mess up a floodplain. Instead, I usually work with a CAD designer to line up the data correctly. This could be easy, like asking a “scale factor” and scaling the drawing myself in CAD. Or it could be difficult, requiring survey to shoot control points and having a designer match them up or, if survey isn’t an option, georeferencing the drawings to the best of my abilities in GIS.

On some occasions I am required to convert our high-quality CAD data to GIS files. One reason is to make the data easier to manipulate; due to the differences in software platforms, tracing and snapping functions may not work correctly in GIS. Second, we might convert the CAD data to help us generate elevation surfaces for use in GIS. Our GIS surface could be built by using surveyed shots as our point data, or it could be generated from polyline contours created in CAD. Even better, the surface could be built by converting a LandXML file from CAD to an Esri grid for use in our floodplain modeling or profiles.

But the main reason we convert our CAD files to GIS is to create complex databases around the datasets. For instance, once our utility line data is converted to GIS, we create attribute data to populate it with information. This can be anything from line types and sizes to hyperlinks for plan sets. And once all of this data is in a GIS database, we are able to run complex SQL queries on the data easily.

Converting CAD layers into shapefiles is relatively easy; you just right-click on the layer in ArcMap and export it. Running the tools to repair geometries, generate polygons and points, dissolve and intersect layers, and snap and split lines can be a little more complex. Populating our new GIS fields with information can also take a significant amount of time. But all of this work is well worth it when it comes to performing complex analyses and creating beautiful maps.

What kinds of projects do you support as GIS manager?

Our GIS group creates maps and databases for all of our civil engineering departments. For our Hydrology & Hydraulics group, for example, we create location, floodplain, and topographic maps. These can be used to show water ponding and flooding, areas of clearing and fill, and detention pond locations. We may even generate new floodplain maps for FEMA submittals.

For our Land Development and Municipal Utility District groups, we produce aerial exhibits and site maps of subdivisions, land plans, and facility locations. We also transfer CAD infrastructure utility maps into GIS, showing sanitary sewer lines, water lines, and storm line locations. Then, through CCTV programs and analysis, we can show areas where problems have been detected and indicate required repairs.

Menard uses a variety of programs and databases to produce detailed utility maps.Click image to enlarge.

For our Public Works group, we work on road rehabilitation projects or new construction, showing right-of-way, utility, and property line locations and generating spreadsheets to notify property owners of construction or other types of development in their area.

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