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16 The data visualization tools available to the practicing geo- technical engineer range from simple x-y graphing programs to sophisticated software systems that integrate multiple graphics tools with complex databases and data and image acquisition software. Visualization software is available in proprietary and open-source formats. Open-source software is developed and supported by an online community of develop- ers and users and is generally free to the end user. Most of the GDV tools available today are desktop software programs; but online, cloud-based tools are becoming more available. Geotechnical engineers have the multiple challenges of identifying which visualization tools to apply in any situation (e.g., hazard mitigation, disaster response); knowing how to effectively apply the tools; and keeping abreast of new tech- nology. The following sections provide an overview of the available types and variety of GDV software. Although this study report is focused on visualization of geotechnical data for hazard mitigation and disaster response, the visualization tools discussed in this report are equally applicable to transportation system activities such as planning, design, construction, and maintenance. The number of different software programs cited in the following sections was deter- mined from a search of the geotechnical literature and Internet for geotechnical software vendors, open source organizations, and online software providers (see Figure 11). The software titles identified in the search are listed in Appendix D. Inclusion of a software title in these lists does not imply an endorsement of the product by the National Academies of Science or the TRB. There may be other software programs not identified by this search that are being used by geotechnical professionals. SPREADSHEET SOFTWARE There are about three dozen different proprietary desktop spreadsheet programs; at least seven proprietary online spread- sheet programs; and a dozen or so open-source spreadsheet pro- grams available. Despite this variety, every geotechnical leader at the DOTs and railroad and pipeline companies reported that they and their staff use the same desktop program. The advan- tages of using a common spreadsheet program include ease of sharing data and methods. The most common use of spreadsheet programs for visu- alization of geotechnical data is to generate x-y graphs to explore and illustrate data relationships. Most spreadsheet programs also have the capability to generate pie, bar, and other chart types that may be useful in geotechnical engi- neering practice. The widespread use of spreadsheet programs in visualiz- ing geotechnical data is a double-edged sword. A spreadsheet program provides powerful calculation and visualization capabilities while being relatively easy to learn. However, the proliferation of spreadsheet files can be a data and file management challenge and difficult to maintain with a high level of quality control. Concern for spreadsheet qual- ity control led to formation of the European Spreadsheet Risks Interest Group (http://www.eusprig.org/index.htm). Although most of the cautionary tales on this website refer to disciplines other than engineering, the lessons learned and advice offered are applicable to geotechnical uses of spreadsheet programs. BORING LOG GENERATORS Boring logs are generally the geotechnical engineerâs pri- mary method of visualizing and presenting subsurface infor- mation. Whether they are soil boring logs, rock core logs, cone penetration test logs, or any of a number of other sub- surface explorations, the log typically contains a visual rep- resentation of one or more subsurface data elements versus depth or elevation (see Figure 12). This visual representation provides the geotechnical engineer with a first-order analysis of soil or rock layering, groundwater location, and material properties. A boring log (or other log type) generator is a software program that accepts user data input, stores the data electron- ically, and outputs a completed log to hard copy or an elec- tronic file. Most boring log generators required that the data be input manually, but some have the capability of accepting data from hand-held mobile devices. Approximately 40 proprietary and shareware desktop bor- ing log generators are available; although spreadsheet and computer-aided drafting (CAD) programs are also used to generate boring logs. The most comprehensive boring log gen- erators are supported by a desktop or server database and can be used for logs of soil, rock, core penetration tests, and other subsurface explorations. chapter five CURRENT GEOTECHNICAL VISUALIZATION TECHNOLOGY
17 Approximately 80% of the DOTs surveyed use the same vendorâs boring log generator. FENCE DIAGRAM GENERATORS The fence diagram is the geotechnical engineerâs second- order method of visualizing and presenting subsurface infor- mation as it merges the information from several subsurface explorations to create a cross-sectional view of soil or rock layering, groundwater location, and material properties (see Figure 13). There are a dozen or so proprietary desktop fence diagram generators available to the geotechnical engineer. The ability to generate fence diagrams is integrated with several of the boring log generators described previously.FIGURE 11 Geotechnical data visualization software used. FIGURE 12 Typical boring log.
18 Approximately 70% of the DOTs surveyed use the same vendorâs fence diagram generator. LABORATORY SOFTWARE Laboratory software includes programs to control laboratory tests, record laboratory data, convert the data to meaningful engineering units, and visualize and present laboratory test results. More than 80 proprietary desktop laboratory programs are available to geotechnical laboratory technicians and engi- neers. Some of these programs only calculate the results of a specific test or control and measurement, but many have at least a rudimentary capability to visualize test results. The most comprehensive laboratory programs are supported by a desktop or server database, have strong visualization fea- tures, and integrate well with other geotechnical applications. Approximately 60% of the DOTs surveyed use laboratory software. Despite the wide variety of commercial software available, approximately 20% use department-developed pro- grams or spreadsheets to record, calculate, and visualize their laboratory data. GENERAL PURPOSE DATABASE SOFTWARE General purpose database software includes proprietary and open-source programs that efficiently collect, store, and retrieve large quantities of geotechnical data. This software is often used in conjunction with other software applications, such as the boring log generators and laboratory software described previously. At least a dozen geotechnical-oriented proprietary desk- top database programs are available. These applications can be used to store a wide variety of geotechnical data includ- ing exploration data, laboratory data, and analytical results. These applications are built on the same proprietary or open- source database engines that underlie many database appli- cations in other disciplines. About 46% of the DOTs surveyed use general purpose database software to support visualization of geotechni- cal data. However, no single vendorâs software dominates this area. GENERAL PURPOSE X-Y GRAPHING SOFTWARE In addition to the ubiquitous spreadsheet, there are more than 100 proprietary and open-source x-y graphing programs available for the desktop or on line. This software is used to visualize data relationships and time trends for field and labo- ratory data. Some of these programs also have basic statistical analysis capabilities. About 40% of the DOTs surveyed report using general purpose x-y graphing software; however, approximately half are using spreadsheet software for this purpose. FIGURE 13 Typical fence diagram.
19 GENERAL PURPOSE CONTOURING SOFTWARE Contouring software is used to visualize three-dimensional data. The most frequent geotechnical use concerns ground surface topography and subsurface contacts, but the contouring is also useful for visualizing multi-dimensional data relationships; for example, contours of limit equilibrium factor of safety against sliding for a range of cohesion and angle of friction values. Geotechnical engineers have a choice of about two dozen proprietary and open-source contouring programs. The major- ity of these programs are desktop rather than online applica- tions. The more comprehensive contouring programs have strong visualization features and can import three-dimensional data and support image overlays from a variety of sources. About 40% of the DOTs are using contouring software. Among those DOTs using contouring software, approximately 35% are using CAD software for this purpose. GEOGRAPHICAL INFORMATION SYSTEMS GIS are a class of software that integrates spatial and other data with map-based visualization. GIS applications are especially useful for creating thematic maps and inter - active maps that display the data behind the images on the screen. There are about 20 proprietary desktop and server-based GIS software packages and eight open-source GIS packages. However, one software company currently dominates the GIS market; among the 46% of DOTs using GIS software, only one is using another vendorâs software. The image in Figure 14 illustrates a typical GIS geotech- nical application. The colored overlays identify a landslide zone and specific landslides or debris flow events on a bluff above a major commuter and freight railroad. Each red sym- bol is the location of an investigation of a prior landslide or debris flow event. In the center of Figure 14 is a box pro- viding a photograph and additional information about the event, which can be retrieved by clicking on one of the event location symbols. INSTRUMENTATION SOFTWARE Instrumentation software includes programs to schedule, col- lect, process, and visualize data from an array of field-installed instruments. Some instrumentation software serves a specific instrument type; for example, inclinometer software is often FIGURE 14 Sample GIS application.
20 a single purpose application that reduces instrument readings to engineering units and presents the results as a visual rep- resentation of displacement versus depth. Other instrumenta- tion software is more general, serving a variety of instrument types and providing at minimum rudimentary graphing capa- bilities for data visualization. There are at least 17 proprietary general purpose desktop and web-based instrumentation programs available. All are supported by a database to manage and store the large quan- tity of data generated by instrumentation arrays. The more comprehensive systems schedule and collect raw instrument data, reduce the data to engineering units, and provide flex- ible graphing capabilities for visualization. IMAGE ANALYSIS SOFTWARE Image analysis software describes a broad class of programs that are used for spectral analysis, spatial pattern analysis, difference analysis, and similar analyses of high resolution images. The software to be used depends heavily on the scale of the images, which can range from thin-section images to satellite images. One of the key applications of image soft- ware is difference analysisâa comparison of images of the same location taken at different times. Image analysis soft- ware is used to automate the process of finding and highlight- ing the differences between two images. At least 10 image processing software packages are avail- able, of which several are open-source packages. Because of the different purposes of image processing and different scales of the images to be processed, it is unlikely that any single image processing package would serve all needs. About 22% of the DOTs surveyed report that they use image analysis software. The software that they use is a mix of GIS, terrain modeling, and ground penetrating radar (GPR) post-processing software. WEB-BASED IMAGING SYSTEMS Web-based imaging systems provide the geotechnical engi- neer with a convenient, and often inexpensive, method of obtaining air photographs, LiDAR, satellite and other remote sensing images. Public agencies such as USGS, NASA, and other government agencies provide free and low-cost images. Several free, but copyrighted, sites and commercial sites are available as well. While only about 20% of the DOTs surveyed reported using web-based imaging systems, it is clear that more DOTs are using these systems because of the number of DOTs who report using LiDAR, satellite images, and other remotely sensed data. OTHER APPLICATIONS Many geotechnical analysis software packages also include visualization features. For example, software packages for stability, pile capacity, and retaining wall analysis often incorporate useful visualization tools. Finite element and finite difference soil-structure interaction software packages frequently have multiple visualization features including x-y graphing and contouring. Other potential sources of visualization software are the fields of mineral and energy exploration, biology, and medicine. More effort appears to have been expended to develop data visualization tools in these fields than in the geotechnical field, advances that might be adaptable to GDV uses.
