Moviemaking for Civil Engineers (From the Trenches AutoCAD Tutorial)12 Apr, 2006 By: Salvatore Napolitano
How you can make a movie showing contaminant concentrations using Land Desktop and Film Maker.
You can do a lot with Autodesk's Land Desktop using survey points: build a 3D surface, cut sections through the surface, profile along the surface and create thematic maps showing elevation or slope changes with color bands. But can you graphically display concentrations of contaminants, such as lead or arsenic in the ground? Yes, you can.
The Fourth Dimension
Land Desktop provides three dimensions of the real world as input: length, width and depth, or x, y and z, respectively. The first step is to use the z coordinate, which we typically designate for elevations of a surface, for concentrations. It will therefore function in terms of milligrams/liter instead of feet or meters of elevation.
Land Desktop does not accept a fourth coordinate, which usually is thought of as time. To solve this problem, I downloaded Autodesk's free Film Maker software. With it you can add the dimension of time to your data, so you can show contaminant movement underground over time.
To develop an example of this procedure, I went to the U.S. EPA (Environmental Protection Agency's) Web site to query contaminant data for the Gilson Road Superfund Site in Nashua, New Hampshire. The amount of data was staggering, and I was glad that a contact from the NHDES (New Hampshire Department of Environmental Services) was able to e-mail me the specific data.
I first used Autodesk Map to bring an aerial photo of the site into an AutoCAD drawing from the New Hampshire State GIS Web site. The NH DES sent an Excel file that I modified to be acceptable as Land Desktop point input data with arsenic chosen as the contaminant of interest. Arsenic has an acceptable limit of 0.01 mg/L according to NHDES Method 1 GW-1 Groundwater Standards. The concentration ranged from 0.0000 mg/L to 0.3200 mg/L, or 32 times the limit for the wells chosen.
After I brought all of the points in, I created point groups for the well test dates to separate time periods. I used the Terrain Model Explorer to create five time periods using the point groups as input (figure 1). I used solid banding to display concentration bands and a legend (figure 2).
Figure 1. I created five time periods using the point groups as input.
Figure 2. Solid banding displays concentration bands and a legend.
After I created the surfaces, it was easy to get a Quick Section from the Terrain pull-down menu (figure 3).
I made slides showing arsenic concentration bands overlaid onto an aerial photo at different times using AutoCAD's Mslide command. I then used Autodesk Animator FLImaker, a free utility that converts slides into a film, to make the movie clip. With this program you can control speed and duration (figure 4) and even add sound to your movie clip, although I found it unnecessary in this case.
Figure 3. I created a section cut from the Terrain pull-down menu 'view quick section'.
Figure 4. With Autodesk's free Film Maker utility, you can control speed and duration of the image.
I could not get the movie clip to fill the screen with the fill screen option and the aerial photo displayed poorly in the movie clip. In the end, I would prefer to show individual slides of each time period of concentration over an aerial photo (figure 2) with an included section cut. Nonetheless, it was interesting to use the power of Land Desktop's terrain models, section cuts, profiling and surface display options to show contaminant concentrations graphically.
About the Author: Salvatore Napolitano
In her easy-to-follow, friendly style, long-time Cadalyst contributing editor Lynn Allen guides you through a new feature or time-saving trick in every episode of her popular AutoCAD Video Tips. Subscribe to the free Cadalyst Video Picks newsletter, and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!