Point of Beginning

A New Life for Digital Data

April 21, 2003
LandXML offers an effective communication vehicle to the civil engineering, construction and surveying industries.



The LandXML concept is a new and valuable resource to the civil engineering and surveying industry. All components of our industry should take note of this tool because it affects each player. Surveyors can access data and retain the intelligence behind CAD drawings for review and stakeout. Surveyors can also send LandXML data directly into some of the GPS-guided, machine control excavation equipment for direct use in construction. Engineers can share their design data with others on a project in an application independent fashion. Project managers can obtain various aspects of their projects for visualization and analysis. The beauty of all of this is that the design intelligence can be migrated between different software programs and accountability can be maintained between disciplines.

LandXML offers several strategic benefits for the civil engineering, construction and surveying fields. Professionals in this industry use a variety of software application programs to map, design, review and construct project sites. Digital data is developed within those CAD projects and much of it resides behind the scene in external files or databases. This information contains the very essence of our work effort. The CAD drawings that accompany our projects often contain the output from this digital data, albeit in a largely static state, object technology notwithstanding. Industry-oriented application software such as Autodesk Land Desktop or Bentley InRoads serve as a conduit for accessing and manipulating the digital project information. This in turn can be linked back to the CAD graphics either manually or automatically. With the advent of LandXML, digital project data finds a new life and can be used for many other aspects of our business, particularly since we do not all use the same application software, nor do we all have the same uses for the data.

The LandXML concept offers an effective communication vehicle that allows us to maximize the use of our data to levels unheard of just a few short years ago. We can now port our project’s intelligence consisting of road geometry, utility information, parcel data, 3D surface networks and point data to other venues for a myriad of purposes. Let us explore some examples of these benefits in brief detail.

Sharing Project Data With Other Parties

LandXML allows users to provide access to their project’s intelligence to other parties involved. Say, for example, that a user has a project that includes a hydrologic component to be performed by a subcontractor. The subcontractor may need access to only the hydrologic-related aspects of the project. LandXML will send only the required portions of the project’s data to the subcontractor. Terrain information is often an important aspect of this type of analysis and retaining the original intent of the terrain model is crucial. LandXML can be used to send over the correct terrain models and the user can then import them and retain their intended and original integrity without reprocessing the TIN data. Worries about algorithmic differences in the processing or interpretation of data types such as whether the software can read 3D breaklines or 3D faces, etc., are eliminated. Both of these concerns impact whether a reprocessed TIN will be the exact reproduction of the original model.

An example of some of the protections that exist in LandXML are shown in Figure 1. Note that the original intention of the sender’s TIN can be held with the “Maintain Triangulation” button. Other helpful features within LandXML include the ability to select only those components of design that are needed from those provided. In other words, a user can select one surface and one road alignment from many that are in the LandXML database.

An engineer or surveyor can also use LandXML for his or her own purposes, such as checking whether his or her version of the project data has changed over a duration of time. Let’s say that at a specific point in time a LandXML export is performed. The project data might be altered at some time afterward. The LandXML command in the software program can be used to check if the data has been altered without actually importing it. Any differences between the project data and the LandXML data are identified to the user. This adds a whole new dimension to project management and quality control never offered before. This is because one of the interesting features of the LandXML format is that it is highly suited for making inquiries and generating reports (see sidebar on page 11) using HTML and stylesheet formatting. Many stylesheets are available on manufacturers’ websites and are intended for customization and sharing.

Figure 1. LandXML users can protect their work with certain import data options.

Sharing Data Between Different Application Software

LandXML allows users to provide access to their project’s intelligence to other parties involved. Say, for example, that a user has a project that includes a hydrologic component to be performed by a subcontractor. The subcontractor may need access to only the hydrologic-related aspects of the project. LandXML will send only the required portions of the project’s data to the subcontractor. Terrain information is often an important aspect of this type of analysis and retaining the original intent of the terrain model is crucial. LandXML can be used to send over the correct terrain models and the user can then import them and retain their intended and original integrity without reprocessing the TIN data. Worries about algorithmic differences in the processing or interpretation of data types such as whether the software can read 3D breaklines or 3D faces, etc., are eliminated. Both of these concerns impact whether a reprocessed TIN will be the exact reproduction of the original model.

An example of some of the protections that exist in LandXML are shown in Figure 1. Note that the original intention of the sender’s TIN can be held with the “Maintain Triangulation” button. Other helpful features within LandXML include the ability to select only those components of design that are needed from those provided. In other words, a user can select one surface and one road alignment from many that are in the LandXML database.

An engineer or surveyor can also use LandXML for his or her own purposes, such as checking whether his or her version of the project data has changed over a duration of time. Let’s say that at a specific point in time a LandXML export is performed. The project data might be altered at some time afterward. The LandXML command in the software program can be used to check if the data has been altered without actually importing it. Any differences between the project data and the LandXML data are identified to the user. This adds a whole new dimension to project management and quality control never offered before. This is because one of the interesting features of the LandXML format is that it is highly suited for making inquiries and generating reports (see sidebar on page 11) using HTML and stylesheet formatting. Many stylesheets are available on manufacturers’ websites and are intended for customization and sharing.

Sharing Data Between Different Application Software

Another benefit of LandXML is the ability to provide project data to others with different application software. In many companies or agencies, different departments have acquired different software solutions. Yet they must work as a team. How do we maintain the integrity and value of the design data as it migrates between departments? Well, the good news is that LandXML has already begun to proliferate. We have this functionality today in Autodesk Land Desktop 3, Eagle Point’s Surveying and Civil Design products, CAiCE Visual PE 9.1, Carlson SurvCADD XML, Topcon Topsite, Bentley InRoads and Bentley GeoTerrain.

The LandXML process creates a file format that is not proprietary or software dependent. Because of this, design data can move freely between software programs. As the concept and use of it flourishes I feel confident that support will increase even further. Industry users should take note of this technology because it allows sharing of design concepts, mathematics and output in a way that is void of binary format and even operating system dependence. Many users have identified problems when trying to move binary files between a Windows operating system and UNIX-based workstations. The XML nature of this format allows it to move between the two systems much more freely. The software independence of the format also allows us to think long term in areas of project archival and retrieval. Many firms perform judicious backups of project data and archive it when the job is complete. However, not many companies archive the software that developed. So realistically, it could be quite difficult to re-create a design several years from now if the manufacturer’s file formats change in the interim. Even if the software were to be archived along with the data, there is no guarantee that it will run on the operating system that it might be installed on several years from now.

Again, the concept of LandXML comes into play. Users can now create time-independent archives of project data in a generic format that can be read through web pages, stylesheets, word processors, etc. As manufacturers add support to this file structure it could become a standard tool in software, allowing users to read data developed today for years to come.

Sharing Data Between Different CAD Software

The benefits of LandXML continue for civil engineering CAD users. Many times CAD users are requested or required to share data with others who may use a completely different foundation CAD system. For example, an AutoCAD user needs to make his road design available to the state department of transportation. The designer may have completed her design, drafted the road and developed construction plans. If she needs to provide that data to a review agency privy to the information, she may find that the other party has an entirely different CAD system. That means she must translate the data. DXF files may need to be generated or DWG may need to be translated to or from DGN. There is also the issue of sending and receiving CAD systems calculating the data in different ways. We have all experienced issues when transferring data from a floating-based CAD system to or from an integer-based CAD system. LandXML is CAD system independent and is non-proprietary. As a result, it can be used to avoid many of these problems. The data can be output in several fundamental formats such as international feet, U.S. survey feet or metric units. The user can control precisions, although maximum precisions are probably preferable. The user can export data from an imperial project, and then import it into a metric project to scale and convert values. If project coordinates need to be modified en masse, there are Translate and Rotate commands that can be used for globally adjusting coordinates or elevations.

LandXML can generate useful reports in various formats. Headings and ancillary information are automatically placed on the report based on customer pre-sets found in the Settings tab.

Sharing Data Between Different CAD Standards

Another issue that often arises when providing others with data involves the aesthetic look of the graphics. Whose CAD standards should be maintained and how much effort will it take to accomplish this? If we need to send or receive project data involving others who have a different set of CAD standards, issues arise. When the data is brought over to another organization’s CAD system, whether AutoCAD to MicroStation or even AutoCAD to AutoCAD, many aspects of the CAD file may need to be altered aesthetically. Few firms can agree on colors, lineweights or linestyles. If LandXML is used to send the pertinent data to the receiving CAD system, the user can import the information using his or her own native CAD standards and be unencumbered by what occurred graphically before. The LandXML export sends out only design data, not the graphical appearance of it. The LandXML import would take on the attributes or properties of the CAD system performing the import. The vital aspect of this process is that the design integrity is maintained, not the aesthetic integrity of what color something is or what linetype it was originally drawn with. This benefit of LandXML will enhance the sharing of data immensely while maintaining accountability of those who developed it.

Using Data for Visualization and Ancillary Analysis

One of the most exciting growth areas for software usage in this industry during the past few years has been visualization and data analysis. The market is beginning to split into two areas for each discipline. One area concentrates on designing the project, drafting and producing construction plans; the second market is focusing on adjunct uses of the data such as the ability to view the project data in state-of-the-art ways or to perform additional analysis. A good example of this is the Autodesk OnSite Desktop workstation. It allows users to import LandXML data and perform a certain level of terrain analysis or visualize the site in interesting ways. For instance, one can import the terrain data and drape an aerial photograph or a digital orthoquad (DOQ) sheet on top of it. Imagine viewing the project from a bird’s eye view where the nearby river actually resides in the 3D terrain model in the riverbed! The user can screen back various overlays to illustrate pertinent parts of the site for discussion. Pipelines can be projected into the data in 3D with the site being rotated to show additional viewpoints.

Along these same lines is the advent of GPS-guided, machine control for excavation equipment. Several software packages available today include the ability to take a proposed ground surface and send it into the machine control formatted files. Some of them directly support taking the LandXML surface data and migrating it to machine control language suitable for direct linking with the field equipment. This might begin to address potential liability questions that arise when this is used in lieu of field survey stakeout.

Sharing Data Is The Future

The LandXML concept is here now and is already supported by many manufacturers. It allows a future of data continuity that is software independent and non-proprietary, and introduces archiving and transport abilities that beg to be used. And by the way, if the user wants to port the graphical entities to other software, there is an additional function within AutoCAD 2002 called Design XML that allows for this. This function imports and exports graphical AutoCAD data and could be a precursor to the potential end of DXF files.

LandXML Report Generator

A newly available program for Autodesk customers significantly expands the power and uses that LandXML provides to customers. The extension runs independently of the AutoCAD application and is used to generate and customize reports from any LandXML data files. Predefined report forms are supplied with the extension, which can be modified to suit any customer’s needs or new report forms can be produced.

The LandXML format is a rich and in-depth, text-based language that can contain a lot of project information that may not be pertinent to all who use the file. Many users will only require a subset of a project. Although the data is clearly represented in the file, customers can obtain quality control, archiving and reporting benefits by using this reporting solution. The Report Extension allows those reading the file to quickly and easily format the section of information they need in a form that is suited for them.

After launching the Report Extension from the Windows Desktop or Start button, a user can open the LandXML file produced in any program outputting LandXML. It reads through the file and parses the data into categories for the customer that include the project name, the units for the data, the name of the application that generated the information, COGO points, surfaces, parcels, alignments and pipe networks. It briefly lists how many of each of these items exists within the file. It has tabbed, Explorer-style interface so one can easily collapse or expand the trees involved or move to related functions. For instance, in the Data Summary Tab, if a surface is expanded, it shows the names of each surface and each of those has a collapsible tree structure to it. Within the tree for an individual surface, it shows another collapsible tree that describes the surface type and fundamental TIN information such as 2D and 3D TIN areas, and minimum/maximum elevations. This also expands and shows how many points and TIN faces exist within the surface.

Another example might include an alignment. This tree shows all alignment names and their respective starting and ending stations. These expand to show CoorGeom (coordinate geometry), which displays how many geometry elements exist within the alignment. This field expands to list each geometry element and provides information such as curve radius and length.

Other tabs include Forms Tab used to generate predefined reports from the Settings Tab, which controls customer pre-sets, and the Output Tab. The Settings Tab has defaults, precisions, report formatting, and many customer controllable variables for accepting or resetting how the data will appear in the final report. For example, the profile’s starting stationing can be reset if needed.

The LandXML Report Extension can also read LandXML files created by other application software packages. The report extension takes a large dataset and generates very professional reports that are suitable for display on the Internet, in engineering studies or reports. The LandXML data and some of the accompanying reports are great for such tasks as deed recordation or project archival purposes, or to send to members of the project team who are not CAD experts.

After opening the LandXML file, the customer then selects which form to use for reporting. Many excellent report formats are provided in the software. Alignment, profile, cross section, point, surface, parcel and Autodesk OnSite Desktop reports are all pre-developed for the customer. These report forms can be customized as needed. If the report form the user wants to use is not listed on the Forms tab, a report form can be opened using the File menu. These forms are XSL style sheets and can be located on a local disk drive, on the network or on the Web. (Further information about XSL style sheets can be found at www.landxml.org.)

The report generator creates deed descriptions indicating metes and bounds, inverse and area reports and surveyor certificates!

If the customer wishes to generate a report on alignments for example, he or she can select the alignment report, which has two provided options, alignment/curve and station/curve. The first option shows tangent and all curve data for the alignment. The second option shows stationing and coordinate data. Each comes in handy depending on who is inspecting the data. (See example.)