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Trimble Terramodel versus Autodesk Land Desktop Software: An Independent Comparison

Autodesk commissioned this review by Harry O. Ward, P.E. Mr. Ward is a Registered Professional Engineer and an Autodesk Authorized Consultant with more than 23 years of experience in civil engineering and computer-aided engineering, design, and drafting. He is well known in the industry for his pioneering efforts in computer animations, computer forensics and litigation, consulting, teaching, lectures, and publications. He has held the positions of Engineer, CADD Manager, and Director of IT for consulting and industrial firms and is currently the Vice President of OutSource Inc. Mr. Ward is a recurring author for several magazines including CADence and Point of Beginning and has been a member of the engineering faculty at George Mason University since 1997, where he teaches CEIE 290, “Engineering Computations and Design.” He was recently appointed to the Editorial Advisory Board of Point of Beginning magazine and was a featured speaker at Autodesk University®.

The following report has been minimally edited for editorial and formatting consistency.

The software described below was reviewed comprehensively and from a workflow point of view. I analyzed the interface, algorithms, and functionality as a practicing engineer or surveyor would in an on-the-job fashion. The sections covered include the following:

·        Project management, interface, and settings capabilities

·        Primitive geometry and geometric layout capabilities

·        Terrain modeling, terrain analysis abilities

·        Alignment design and editing features

·        Profiling and vertical alignment design and editing features

·        Road design and cross-sectioning features

·        Plan preparation

·        Site design

·        Hydrology and rainfall analysis

·        Retention pond design and pond routing

·        Special features

My method of operation was to look at Trimble™ Terramodel® software (see www.trimble.com/terramodel.html) in an objective fashion and to compare it to Autodesk® Land Desktop 3 software.

Project Management, Interface, and Settings Capabilities

Terramodel: The interface is a Windows® compliant interface. There is no traditional CAD system in the software such as AutoCAD® or MicroStation®, but there are strong translation tools that allow the import and export of data between these drafting programs. Tutorial files are included with the installation of the software. Coordinate point data can be converted between more than 600 coordinate systems using NAD27 or NAD83 and latitude/longitude. All NAD27 and NAD83 State Plane Zones and UTM Zones are contained in a coordinate system dictionary. The data can be stored in the user’s choice of directory and it is capable of being run from a server. The interface pulldowns are laid out in almost direct conjunction with the modules they offer. Hardware locks are used to dissuade copyright violators.

The menus are arranged by function so that viewing commands allow for viewing tools and for viewing all of the data. The data is contained in a project database and hence the viewing commands are needed to display the data to the screen. Toolbars can be customized by the user and recalled during the next working session automatically. Internal settings control text heights, symbology, layers, and colors of the objects. Passing the cursor over a line or linestring immediately displays a tool tip that shows these features. Drafting functionality is available in the CAD Module since there is no traditional CAD system associated with the software. But Terramodel uses this to its advantage in that graphics, contours, and text compute and display with great speed. All attribute text is updated automatically when any design changes are made to ensure high accuracy and speed up the drafting process.

One of the reasons why surveyors tend to like this software is that it is highly point based. Lines and arcs are automatically created based on point descriptors. The lines, arcs, and points are then automatically placed on settings-based layers and given settings-based linetypes and colors. The system is quite self-contained, and all legal and production reports and all graphics are generated using the CAD module.

Of course there is the ability to read and write Autodesk DXF™ and AutoCAD DWG files. However, there are significant problems associated with data transfer between the two programs. The most annoying problem is that arcs are computed differently by AutoCAD and Terramodel. In Terramodel they are point based; for instance, there are PC, RP, and PT points that create the arc. In AutoCAD, there is a center point, start angle, and ending angle. Because of this in many cases the tangents and arcs do not come together well when transferred to AutoCAD. Symbology transfers have also caused problems going between AutoCAD or MicroStation since they use a font file for symbols.

Autodesk Land Desktop: The interface is a Windows compliant interface. Land Desktop works inside the industry-standard AutoCAD 2002 CAD system. The main package is essentially for 2D project work plus terrain modeling and earthwork takeoffs. The Autodesk® Civil Design and Autodesk® Survey modules are add-ons and each has menus specific to their function with parts of Land Desktop integrated into them. The menus are customizable by the user and there is a facility to support this. Land Desktop is the leader in being able to develop an enterprisewide set of CADD standards. Project settings, drawing settings, and AutoCAD settings support the development of graphic objects for viewing and plotting. They can be centralized on a server or set on a machine-by-machine basis.

The external project database method is mature and flexible and has had feedback from thousands of customers over the past 10 years. XML is supported in Land Desktop 3. A feature evident throughout the software is the ability to access point data via the use of point filters. This allows for easy access to points that exist in either the CAD system drawing or the external project point database. Land Desktop comes with tutorial files and with the advent of Autodesk Map™ software being included, it has enormous capabilities to handle geodetic data and perform geodetic conversions. Land Desktop allows translations to ARC/INFO®, ArcView®, MapInfo®, and MicroStation. The tools offered in Autodesk Map allow for drawing cleanup, GIS, and external database linking and querying. It also allows for super cross-referencing of huge spatial data sets consisting of graphic data, database data, and object data.

Land Desktop makes great use of the 3D Orbit command in AutoCAD for viewing data in 3D and in perspective. Several types of shading are built in and can remain shaded while working. Although CAiCE has many specialized commands for civil and survey functions, Land Desktop has a myriad of commands to achieve similar results.

Land Desktop can also track who logs into the drawing and what changes have been made to graphics through the Revision Additions command. It stores the information in a database that can be searched at a later time and interacts with the graphical elements to highlight modified data.

Benefits: Users benefit by Land Desktop’s integration with AutoCAD and Autodesk Map plus the object technology that Land Desktop uses. The Terramodel product is quite strong in its surveying and design abilities but it has always had problems bringing the data to AutoCAD or MicroStation.

Primitive Geometry and Geometric Layout Capabilities

Terramodel: The COGO Module was designed to perform highly accurate design and survey calculations, and the manufacturer has always prided itself on their speed. COGO uses a 3D database with unique point descriptors for all standard geometric routines. All calculations make use of the point-based engine, which provides unequaled accuracy and speed.

All traditional survey coordinate geometry calculation routines are available. The system uses points, sets, polylines, text blocks, and tables. Sets are a special class of line in that they connect a series of points. If a point in a set moves, the related vertex of the set moves with it. Sets can be curvilinear, open, closed, or joined. This is one of the reasons why surveyors like the product, because this is how property data should behave; it reduces liability and assists in the generation of reports. Sets can be used for boundary lines, alignments, breaklines, sewer design, and more.

The Field Traverse Program reduces, balances, and adjusts field traverse information from the data collector. The user can traverse by horizontal angle, distance, and vertical angle. Closed traverse with internal reference, closed traverse with external reference, point-to-point traverse, and open-ended traverses are supported. They can be two-dimensional or three-dimensional. Traverse adjustments can be made using compass rule, transit rule, Crandall, and least-squares methods.

One of the things that is really impressive are the number of snap modes in the software. AutoCAD users have always enjoyed strong object snapping, but this software allows for even more advanced snapping mechanisms. In addition to AutoCAD type snaps, some of the neat ones offered here include these:

·        Factored Snapping allows snaps at a factored distance along a line, an alignment, or any two locations in the project (and the elevation is also interpolated).

·        Gravity snaps to the center of gravity of an object.

·        INTHAL snaps to the intersection of two alignments.

·        Offset and Offset Alignment snaps to object offsets or alignment offsets. There are several other related offset snaps as well.

Autodesk Land Desktop: Land Desktop has excellent land development geometry tools because the user can use the graphics commands in AutoCAD supplemented by well thought out routines in Land Desktop. It has many productive tools to build horizontal geometry. Some good examples include the following: users can draw lines with a “double snap” such as the Perpendicular and Tangent commands and they can use the Create Multiple command which allows for the creation of lines, arcs, and spirals from lines, arcs, and spirals. There are also many commands for settings points in 2D and 3D, and they are designed to operate the way a civil designer or surveyor needs them to. The method of prompting is also well thought out because the command sequence steps users in and then steps them out of the process.

The Autodesk Survey module has additional geometry commands that build traverses and sideshots in 2D or 3D and it can be done graphically or via dialog box entry. A batch file captures commands and allows for editing and playback.

The TDS Survey Link within the product allows for data collection from most of the data collectors in use. Links exist for those that remain proprietary. The methodology is simple and can be augmented by the Survey Command Line commands if they are added as notes.

Benefits of Terramodel: Users benefit from Terramodel’s excellent abilities in performing surveying computations, a specialty for years. The data collection is easy and powerful and does not require a lot of typing by the field crew. Its point snapping is industry leading, and no one respects point data more than Terramodel. On the other hand, those who are used to using curvilinear vectors are in for a letdown because Terramodel is largely a point-based system.

Benefits of Land Desktop: Users benefit from the ability to reduce least-squares networked loops as well as a well-rounded set of commands designed for geometric layout in a CAD system. Curvilinear linework and points are easily created and modified and have a mature prompting sequence that will aid users in production. The Autodesk Survey add-on may be needed if users want the ability to traverse around a lot in a single command or if they want to be able to develop a nontangent curve from curve table data. The use of the Survey Command Line is a valuable tool for those creating geometry in Land Desktop, as it has built-in batch file ability and they can edited and run as needed.

Terrain Modeling, Terrain Analysis Abilities

Terramodel: The terrain modeling abilities of the software are quite strong and exceptionally fast. Contours are generated much faster in this package than in packages that require a CAD host, due to the duplication and synchronization problems found in CAD add-on software. TINs are linked to form 3D triangles in excess of 2,000 points per second.

The routines can handle occurrences that cause problems for other manufacturers such as “finger” contours. There are commands to limit triangle distances and maximum triangle angles. The concept of isopachs is directly supported; that is, a volume consisting of two surfaces can be developed.

Contours created by the DTM commands create some of the most aesthetic shapes in the business. That is because it uses splines in its mathematics of creating the contour. In fact it has two types of splines, the b-spline and the Overhausen spline. The b-spline tends to move the contour more than the Overhausen spline.

Autodesk Land Desktop: The Terrain Explorer provides an excellent interface to the DTM and isopach data. It has a Windows feel to it. Generating a TIN is fast. Statistics are readily available for the data and condition of the data. The analysis tools are among the industry’s most robust because AutoCAD can provide many graphical functions for displaying vectors, fills, and quick graphics. The TIN editing is also powerful and has unique commands for automatic slope annotation, nondestructive breaklines, surface pasting, and object technology for quick sections, contouring, and labeling.

Benefits of Terramodel: Users benefit from some of the fastest terrain modeling software in the industry. This is something that Terramodel has always prided itself on. The contouring is also among the best because of the splining algorithms used.

Benefits of Land Desktop: Users benefit from Land Desktop’s terrain abilities because of excellent TIN editing and TIN analysis. They benefit from the ability to use USGS DEM file data for large-scale terrain analysis. They suffer somewhat because often contours representing the tops and bottoms of hills and valleys are missing if there are no spot shots within the contour source data. For some reason, these “flat areas” often do not produce contours although they are accurately reflected in all TIN data computations for profiling, sections, and earthworks.

Alignment Design and Editing Features

Terramodel: Alignments are defined by sets which connect a series of points. This produces an alignment that is always tied to points, and if points are moved the alignment is moved as well. Any modification function can be used to relocate points or to add or delete points from the set.

Autodesk Land Desktop: Land Desktop uses vector graphics to define alignments. There is no way to develop alignments other than AutoCAD entities or Point Objects. Alignments are contained in an external database and can be freely used in any drawing at any time. Multiple users can work in the alignment database simultaneously, and record locking protects users from stepping on each other. Many commands exist that interact between the alignments and the development of other data such as alignment-based points and offsetting alignments.

Benefits: Users benefit by the maturity of Land Desktop’s networkability and free workflow style. Terramodel users benefit from the way alignments are tied to points.

Profiling and Vertical Alignment Design and Editing Features

Terramodel: Vertical profiles can be computed for existing ground from DTMs or from depth information for subsurface profiles. Proposed vertical alignments are created via a numerical dialog box. When laying out the numeric data, a visual display of the work is produced. It provides all of the typical features needed to lay out a profile and related vertical curves.

The vertical alignment can be graphically edited by simply grabbing and stretching it. The changes are automatically limited by AASHTO standards.

Autodesk Land Desktop: The new Vertical Alignment Editor allows for very good interaction between the numeric dialog and the screen graphics. This is about as state-of-the-art as can be. All AASHTO parameters are built in, and the right mouse button produces a menu with many of the editing functions. The Calculator allows for experimentation and visuals are produced if the customer has a subscription to obtain the Vertical Alignment Extension. Graphics are updated automatically upon exiting the editing function.

Benefits: Users benefit by Land Desktop’s integration into AutoCAD. Land Desktop has all of the tools needed to easily lay out vertical alignments and perform checking for overlaps and AASHTO specifications. Terramodel also has strong design abilities, but getting the data into a CAD system generally has a cost associated with it.

Road Design and Cross-Sectioning Features

Terramodel: The Roadway add-on is for route location and design accommodating streets, multilane highways, airstrips, canals, and earth dams.

Roadway templates can be attached to multiple alignments while still following the centerline. This feature allows users to stretch and modify the template’s shape to handle widenings or adding deceleration lanes.

Cross sections and related earthworks are updated automatically when the DTM changes.

Roadway materials are defined into a library and cross-sections are then cut for existing ground or subsurfaces. Then the user creates roadway shape classes and shapes for the templates of the roadway. Shape classes include such items as shoulders, curbs, and pavement. A numerical editor allows for development of the template and nicely previews activities as they occur.

Superelevation data is accommodated and the user indicates rates and locations in a dialog. A good feature within the package allows for a superelevation diagram showing the profile of pivoting geometry. It allows for overlapping supers to be tracked and handled easily.

Autodesk Land Desktop: Land Desktop has strong tools for single alignment based design. It is powerful enough for corridor design consisting of roads, tunnels, and aqueducts. It is a template-based system and allows for transitioning templates horizontally for lane widenings and contractions and intersection collapsing. It also allows for vertical transitions for sophisticated conditions such as bifurcated highways and nonstandard ditch design. The viewing and ability to edit sections is excellent and very fast. Superelevations are AASHTO based and allow for superelevation-based cross-sections to be automatically created. The software supports subassemblies, which allow users to assemble roadway components into final templates. Land Desktop makes nice use of point codes on templates to mark certain locations for use later in analysis and drafting. The software can automatically create surfaces from roadway data, tying out daylight contours nicely. It can also create 3D breaklines directly from roadway data, which makes it very easy to design cross-sections and cul-de-sacs.

Benefits of Terramodel: Terramodel users benefit in that the system produces exceedingly quick computations. The superelevation diagram is one of the handiest tools I have seen for this purpose by any manufacturer. Again, typically at some point the data needs to be transferred to a CAD system, and Terramodel users pay a price for this in cleanup or integration with other software.

Benefits of Land Desktop: Land Desktop users benefit from having many trained users due to the maturity and popularity of the software. Land Desktop has strong abilities to design roadways geared for land development. The obvious advantage Land Desktop has is that the user is in the familiar AutoCAD system.

Plan Preparation

Terramodel: Plan production occurs using the ASAP routines. With minimal effort and very rapid speed, it automatically creates drawing sheets for the project with a border, title block, sheet numbers, titles, labels, north arrow(s), and “dynaviews” of the desired areas within the plan and profile views. Of course many users then go to a CAD system to flesh out additional drafting and for sharing and plotting.

Plotted sheets are automatically updated when the design changes.

Autodesk Land Desktop: The Sheet Manager has been around for some time and is one of the industry’s most powerful such tools in that it pulls data directly from project databases to assemble plot sheets. It is highly customizable to meet customers’ CAD standards requirements. It can assemble P&P sheets, cross-section sheets, or single profile sheets.

Benefits: Users benefit by both systems in there abilities to produce construction plans. Terramodel is very fast since it does not have to deal with a CAD system per se. Terramodel users benefit because their sheets update automatically when the design changes. Land Desktop users, though, are more likely to develop a finished product because the user has a much more customizable set of features that extract their information from the project databases rather than the graphics.

Site Design

Terramodel: Residential or commercial sites are designed by first defining a template or side slopes for the object. They are then projected onto a DTM surface. Volumes can be computed between these two surfaces and from there the user can view, evaluate, and revise designs. The pads can be moved or otherwise modified, and the cut and fill volumes and slopes are updated automatically.

A simple roadway can also be added to your site with the SMP_ROAD command. This is a good command for preliminary road design since it is easy and fast. Refinement would occur under the roadway commands for more sophisticated parameters.

Autodesk Land Desktop: Very little on the market can compare to Land Desktop’s ability to design sites in 3D. The software has had the ability to do so for a long time and allows the user to use typical AutoCAD entities. The addition of the Grading Object and the powers it has for modification as a design changes is awesome. Land Desktop provides tools that interact with surface data and can extract elevations from any surface on the fly. Between the use of point objects, breaklines, and the grading object there is virtually nothing that can’t be accomplished. The site analysis routines augment this nicely.

Earthwork takeoffs are performed using one or more of the four methods supplied by Land Desktop: the grid method, the composite method, average end area sections, and prismoidal section based methods. Intersection design can occur in 3D and with only a handful of breaklines. They can be easily placed using the software’s exceptional breakline tools that automatically tie the two roadways together.

Benefits of Land Desktop: Users benefit by Land Desktop’s robust 3D tool set for site design and the multiple methods for performing earthworks. Land Desktop has had the philosophy that users should be working in 3D for over a decade. In this area the users need to catch up to the software’s capabilities. Users benefit from both programs’ ability to perform accurate earthworks takeoffs. Terramodel users benefit because of the extraordinary speed in computations (it is often shown in the command prompt). Earthworks are automatically computed as their pads are modified.

Hydrology and Rainfall Analysis

Terramodel: The Sewer Design Module allows for design and analysis of sanitary sewer and storm drainage. Multiple branches can be calculated simultaneously while dependent and independent branches are automatically determined. Pipe sizes and materials are saved in pop-up libraries.

Plotted plan sheets are automatically updated when the design changes.

Flow methods allow for calculating flow rates in a conduit using three methods: Q=Summation, Q=CIA, or None (allows you to directly specify the Q value for each conduit).

The ability to compute watersheds is very fast in its operation. Tens of thousands of points can be computed in seconds, and it always reports how many seconds or tenths of a second it took.

Hydrograph calculation methods include SCS-TR-20 (including 6, 24, 72, and 120 hr. hydrographs), Universal Rational, and Dekalb Rational. Multiple SCS rainfall distributions are included: I, II, III, IA, IIA, Somerset County, and two distributions specific to Florida.

Autodesk Land Desktop: This software has good tools for watershed development and rainfall analysis. TR-55 based methods are routinely used for generating hydrographs. Land Desktop has good tools for storm, sanitary, and waterline drafting. The user can edit pipeline data more readily in this software than virtually anywhere else. Although Darcy-Weisback, Hazen-Williams, and Manning’s equations are available for design and analysis, the Manning’s equation seems most applicable. Because Land Desktop provides a VBA editor/compiler and the pipe database is in Microsoft Access, great potential exists for users to integrate their pipe sizing spreadsheets into Land Desktop. The Sheet Manager produces P&P sheets directly from the pipe database to meet users’ requirements.

Benefits of Terramodel: Users benefit by Terramodel’s ability to design storm and sanitary systems, where sanitary is missing from Land Desktop. Again, its speed in computations is evident.

Benefits of Land Desktop: Land Desktop has excellent graphical previews of the hydraulic results in its calculators. You do not need a PhD in hydraulics to understand what happens in Land Desktop when the flowrate is increased or decreased as graphics preview the results. Land Desktop stores all of the pipeline data in Microsoft Access databases that are conducive to access by Visual Basic for customizing reports. Land Desktop has the Visual Basic Editor and compiler built in.

Retention Pond Design and Pond Routing

Terramodel: Multiple hydrographs can be routed through multiple basins in one step. The software supports multiple basins and ponds, including reach routing. All basin data, pond data, and graphics are saved in the project file. Pond outlet devices include trapezoidal broad crested weir, circular standpipe, broad crested weir, circular orifice, vee notch weir, rectangular weir, cipolletti weir, trapezoid channel, and user-definable devices. A pond may have up to ten devices defined during routing calculations.

Autodesk Land Desktop: Land Desktop has the best interactive features for pond design and analysis in the business. A pond can be built in 3D using such criteria as the storage capacity needed for the pond, depth of pond, pond templates, and more. Once the pond is created, its characteristics can be sent directly into the pond routing and sizing functions. They use the Storage Indication Method for routing and Detention Basin Storage method for sizing ponds. Outlet structures can be developed and set to required elevations. They can further be turned on or off to simulate a variety of conditions. TR-55 and TR-20 are supplied. A variety of hydrograph formats are supported and created. HEC-II card generation is also supported but lacks input for sophisticated conditions.

Benefits of Land Desktop: Users benefit by using Land Desktop because of the interactiveness of the software between pond design and pond analysis. Land Desktop can develop a pond with real life bottom conditions such as low flow channels and forebays.

Special Features

Terramodel: Terramodel is owned by Trimble now and as a result is very strong with GPS data. Trimble sells both the hardware and software for GPS collection and is definitely in a strong position in the industry.

Trimble also purchased Paydirt, which has traditionally been used by contractors for earthwork takeoffs.

 

 

 

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