Trimble WM-Form Review & OptiSurface Comparison


Trimble WM Form is a significant improvement over Trimble Multiplane software however it falls well short of OptiSurface Designer (the leader in this segment for a number of years). Significant limitations of  Trimble WM Form compared to OptiSurface Designer include:

  1. More expensive and offers less functionality than OptiSurface Designer
  2. Any direction drainage designs (e.g. dryland drainage) are unusable because it generates designs that have extremely high earthworks compared to OptiSurface Designer. Eg 1000% higher earthworks for the ‘Drainage’ case study shown below.
  3. 2 Way Designs is not supported. This is where a field has furrows which can drain in both direction due to multiple ridges and valleys.
  4. No analysis tools such as drainage/ponding analysis and erosion risk
  5. Color legend cannot be adjusted, making analysis difficult
  6. Limited 3D View as it can only be used for Proposed Topography
  7. No Profile (Cross Section) view of the field or along a drain
  8. Limited import and export options, understandably for their brand.


Comparative Matrix

The table below compares the features of Trimble WM-Form with OptiSurface Designer.   To lean more about OptiSurface Designer visit

Comparative Matrix

Testing WM-Form

The software was used to test several fields with varying characteristics.

User Interface and Navigation

WM Form user interface.

The user interface has a fairly simple layout:

  1. Project Management
  2. Field Editor
  3. Design Editor

Several fields can be added to a project and each field may be designed using the different types: land leveling, drainage, irrigation and sub-design area. The field editor allows editing the existing topography to a certain extent like adding benchmarks, survey points or other survey data from a file. The boundary cannot be adjusted if needed and the color scale for the elevation is fixed and cannot be edited. Contour intervals may be adjusted but only using the given options: 5m, 2m, 1m, 0.5m or 0.1m. The imported field survey can only be viewed in 2D, but can be zoomed in or out. Distances can also be determined using the 'Measure Distance' tool. Design constraints vary depending on the design type chosen. Constraints can be added to achieve design objectives like minimum slope, limiting cut depth, etc. This will discussed further in design types.

Landform Design Process

WM-Form is landform design software and follows the standard process for design: import topographic survey, calculate a design based on constraints resulting to the Proposed Topography and Cut/Fill Map, then export as machine control file.

Importing a Survey

As Trimble aims for a "One Integrated Solution", survey formats imported is limited to follow their multiplane.txt format: easting, northing, elevation, code.

Sample survey file.

Survey import settings, no boundary points defined in survey.

Easting (x), northing (y) can be interchanged as the user will be asked when importing the survey but the boundary should be clearly defined in the survey else, import is not possible. Once survey file is imported, the field will be shown as a topographic map in the Field Editor. The color scale shows where the low lying areas are but there are no analysis tools to know exactly which areas are experiencing problems and how water flows throughout the field - a key feature in designing.

Existing Topography shown in WM Form.

Calculating for a Landform Design

User will choose between different design types: Land Leveling - a single plane of best fit or multiple planes where hinges can be drawn in the map to define the preferred location. Drainage - creates a design where drains water out of the field, water flow path is not hindered by beds or furrows and can drain in any direction. For this design type, a simple dryland field experiencing water logging across the field will be used for testing.

Drainage Design Example

To calculate a design, design constraints are added, for this example the minimum slope is set to 0.05% and the maximum slope to 1.0%. The Cut Fill Ratio is set to follow the default of 1.2 and the Cut Depth is not limited. A drain channel (brown line) is drawn across the field guiding the software where water is allowed to drain through.

Drainage design constraints

The Cut/Fill Map shows deep cuts where the drain channel was drawn. This resulted to very high earthworks, 3590 m3/ha!

Calculated Cut/Fill Map

OptiSurface Comparison 

Comparing this to a more mature product like OptiSurface Designer, following the same constraints and drain channel, with the addition of the Smoothing Distance of 100 m/%, shows a much acceptable result.

Calculated Cut/Fill Map on OptiSurface Designer.

The Proposed Cut/Fill Map shows cuts in red and fills in purple. Depression across the field are fixed and the drainage channel can easily be identified.

The OptiSurface Earthworks resulted to only 363 m3/ha, that's 90% earthworks savings over WM Form.

The Proposed Topography shows the design with 0.25m interval between colors, with high being higher than the purple areas.

Proposed Topography using OptiSurface.

The drain channel was created using breaklines, enabling the designer to control the shape, slope, width and batter slopes. The Profile of the channel can be seen or edited live as shown in the image below. WM-Form has no options to add features like this drain into the design. 

Profile of drain channel.

Furrow Irrigation Design Example

The 'Irrigation' option creates a design where water drains along beds/furrows and defining where the irritation pipeline is located. Two fields are used for this example, one have the pipeline to one side, another in the middle of the field. This field have beds/furrows running along west-east direction with an irrigation pipeline running along the west boundary as shown by the purple line. The dashed lines shows how the furrows run across the field.

Irrigation design using WM-Form.

Calculation took a few minutes and the report resulted in a Cut Fill Map with a more detailed appearance. Total earthworks resulted to 157 m3/ha.

Cut/Fill Map.

OptiSurface Comparison 

To have an idea of the Proposed Topography, OptiSurface Designer used the same design constraints and it resulted to similar Cut Fill Map.

Estimated Proposed Topography using same parameters on OptiSurface.

This OptiSurface design required earthworks of 121 m3/ha (60 cu.yd/acre). WM-Form's design required  157 m3/ha of earthworks which is 30% higher that OptiSurface. 


Analysis Options

Trimble WM-Form has no analysis options. Analysis options in OptiSurface Designer include Drainage Analysis, Runoff Analysis and Furrow Irrigation Analysis (coming soon).  These analysis are useful to assess the problems for the existing topography and the proposed new topography.  The drainage analysis shows the areas that will pond water (problem) and the flow paths. The runoff analysis shows maps of water velocity and depth for a 1 in 5yr storm. This can be used to understand erosion risk (high velocity) and depth.  Furrow Irrigation Analysis allows you to assess the infiltration depth over a field for varying inflow rates and cutoff times.

Drainage analysis using OptiSurface Designer.


Runoff Analysis using OptiSurface Designer.


Trimble WM Form pricing is based on an upfront cost plus pay per acre fee. The upfront cost does not get you any acres included. The per acre fee is also higher than OptiSurface, particularly when taking into account the discounts available in the OptiSurface Partner Plans. OptiSurface Designer is more cost effective because you pay a lower cost upfront cost AND you also get up to 333 acres included.   This starter pack also includes access to the Online Membership Center which includes an online video training course, one on one training, help center, email support from experienced agricultural earthworks engineers and experts. Additional OptiSurface Credits can be purchased to design fields once the initial credits are consumed. OptiSurface also has six Partner Plans aimed at consultants, contractors and dealers which provide higher levels of support and discounts for higher plan levels.     To learn more about OptiSurface Designer visit

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