Slope Designer Command

D_SlopeDesigner_600ppi   Slope Designer

Command Licensing and Default Menu Location

  • The Slope Designer command is part of the RPS Modeling Toolbox
  • The command is located on the Modeling macros menu ribbon
  • The command is located in the Corridors menu group

Command Description

Provides the ability to create points and or lines using station and combination of either Offset and Elevation, Offset and Delta Elevation, Offset and Slope, Slope and Elevation, Slope and Delta Elevation or Slope and Target Surface. This provides an effective means of defining sideslopes, benches, berms, ponds or pad areas etc. as well as an effective means of entering Station and Offset coordinates to create points and lines for layout of buildings, walls, foundations, footings and structures.

Video Demonstration

Training Video

The following video shows how to utilize the Slope Designer command

Update Video - Version 5.70

In this update we have added an extra Internal corner mode called Chamfer. This has been added to increase productivity and form models specifically for Trimble Curb & Gutter machine operations. A Trimble machine requires a surface model for the machine to run on and an alignment / line to follow for the curb line. Typically the cross slope of the surface for the machine needs to be 0% from the curb line out to the inside (Parking area or pavement area side) by 10’ and to the outside by 2’. When you have a 3D line for the curb line, the problem comes at an internal corner where the elevation is varying around the corner as shown below

Video shows you how this works

Command Download Links

Slope Designer Syles (Updated for Positive and Negative Sideslope Values):
SlopeDesignerStyles.rps (35.4 KB)

Point Creator Settings: (1.4 KB)

Point Creator Settings - Recommendations for Slope Designer:
Point Creator Settings - Recommendations for Slope Designer.xlsx (16.6 KB)

Command Interface Description

The Slope Designer command dialog looks as follows

Slope Designer Styles

Slope Designer uses the concept of “Styles” to manage settings for common scenarios of slope or offset line creation. You can define as many styles that you need for your daily work and then simply select the style required to select all of the pre defined settings of that style. The slope designer styles are all stored in a centrally located settings file (SlopeDesignerStyles.rps) for the command, that allows you to define your styles one in one project and then use in any other project. The settings file location is defined by the RPS Settings command in the File Locations tab.

If you wish to define a new style or to use a new set of user defined settings, select the default style from the list of available styles.

Use the image key to create a new named style, then define the name in the dialog displayed


Use the image key to copy the currently active style to use as the basis for a new style, then define the name in the dialog displayed


Use the image key to edit the name of the currently active style


Use the image key to save the latest updates to the currently active style.

Use the image key to delete the currently active style

Create Lines

Create line checkbox:
Slope Designer allows you to create lines, points or both. If you wish to create lines using this command, check the Create line checkbox. Note that you can first use Slope Designer to create an offset line including the offset corner points e.g. for building or wall stakeout and then use it again to create points at intervals along the offset line that you just created.

Enter the name for the line that will be created using this command

Select the layer on which to place the line from the pull down list of layers. If you need to create a new layer or layer group click the image button.

Create New Layer:
Slope Designer utilizes the RPS New Layer control to create new layers and layer groups when required. For more information on how to use the New Layer function Click Here

Create closed line checkbox:
If you wish the line that you are creating to be closed, check this checkbox. Use this for pads, ponds and foundation / footing lines etc.

** Optimize:**
When you create linework from source lines that incorporate curves, the initial result of those lines will be chorded lines, where the nodes are computed based on the intervals defined by the Location styles (see below).

If you check the Optimize checkbox, then the result lines will be analyzed using the linestring optimizer to convert the chords back into arcs thereby reducing the number of nodes and improving the output smoothness of the line being created. You can elect to Optimize Horizontally, Vertically or both. When you optimize vertically, sequential nodes that lie on a straight grade will be eliminated and vertical curves will be added at the remaining nodes based on the vertical optimization settings to smooth out the vertical profile of the lines being created. The last saved / used or default linestring optimizer settings are applied in this process. For more details on the linestring optimizer Click Here

It makes sense to use the Optimize function for Offset Slope, Offset Elevation, and Slope to Elevation functions. It makes less sense to use the Optimize function on Slope to Surface function because the target surface is not likely to be flat so the resulting tie lines are not likely to create arc geometry. You can optimize to reduce the number of nodes along straight grades or along straight lines however so use this capability as you see fit.

When you are creating a series of offset lines, each line is typically going to be created from the prior line, so optimizing each line to reduce the number of control vertices to a minimum, is beneficial to the creation of the subsequent lines.

Add to surface checkbox:
If you would like to add the line being created to be added to a surface model, check this checkbox and then select the surface from the surface pull down list. Use the TBC Create Surface function to create the surface into which you want to add the linework that you are creating using Slope Designer.

Note: There are two locations in the dialog that ask for surface selection - the location being described here and later there is the option to select a Target Surface for the Slope to Surface type of style. If you create a New surface the surface will automatically be selected in this section of the command dialog, however it will also be added to the Target Surface selection lower down in the dialog - be aware of this issue if you have already selected a Target Surface as you will need to re-select it. This only applies when you create a new surface and not when you are simply selecting a surface from the list of available surfaces. We recommend creating the surfaces prior to running the command.

Create Points

Create points checkbox:
If you wish to create points only or points and lines using the command, click the Create points checkbox.

Point ID:
Select the Point ID for the first point to be created using the command.

Select the layer for the points to be created from the pull down list of layers. If you need to create a new layer or layer group click the image button. (See above for more details on how to use the New Layer and New Layer Group controls.

Feature code:
Enter the feature code for the points to be created.

Computation settings

The Slope Designer command has been developed to tackle the creation of sideslopes and offset lines with specific attention to how internal and external corners are created and managed. Internal corners are notoriously difficult to compute for lines being offset or sloped from 3D lines, because at the corners there are multiple potential elevations.

Internal corners are also complicated to compute at offsets for a number of reasons, especially when you are projecting those offsets to a target surface using a sideslope instruction, which is why in traditional tools in TBC and many other products they create “shoelace” crossovers - again Slope Designer has been developed to eliminate that problem so that first pass results are better.

In addition on external corners, we have leveraged the point creator styles (called location styles here) developed recently to control how many points around a corner (using a radial sweep corner) are created to create the best results, and also how and where to create the computed locations for position and elevation in the resulting lines.

External Corner Options

We recommend creating Styles for the Slope Designer that use appropriate settings for the functions and settings selected. In addition we recommend creating Point Creator Styles (Location Styles) for the two groups of Slope Design i.e. we recommend that you treat the Offset Slope and Offset Elevation functions and the Slope to Surface and Slope to Elevation functions in a similar way.

Place the Point Creator Settings file in the RPS Settings folder (location defined in RPS Settings - File Locations). Download the zip file, unzip it’s content and place it in your RPS Settings folder location.

Use Case Notes

You will find that the Point Creator Style settings that you select will heavily influence the results that are generated using slope designer. The spreadsheet download for Recommended Point Creator Settings provides some guidance as to which settings to use for which slope designer computation method.

The point creator styles that you set depends a lot on what you are trying to achieve. The two main use cases of the Slope Designer are

  1. To create 3D linework that can be used to accurately model design surfaces
  2. To create 3D Points and Lines for stakeout purposes

For surface modeling purposes you will be creating 3D lines with sufficient accuracy to accurately represent the surfaces that you are modeling. In these situations you are primarily creating 3D lines, and the lines will have sufficient 3D nodes to precisely model the surface that you are trying to create.

For stakeout purposes you will be creating points primarily and optionally lines for field crews using total station or GPS equipment. In this mode you want to create the minimum number of points required to facilitate the most accurate stakeout that provides both the required horizontal (shape) and vertical (elevation) controls. On long linear features like walls or buildings, you will likely need to create points at intervals along line segments but only to provide sufficient field control that allows site staff to pull stringline and make tape measurements.

These two very different applications will require quite different settings to achieve the optimum results.

The other factors to consider in your settings is the source linework that is being used as the basis for the slope designer computations. The key things to identify are

Does the source line contain horizontal curves (arcs and spirals)?
Does the source line contain vertical curves (arcs and parabolic vertical curves)?
Does the source line contain multiple elevations along its path (VPIs or 3D nodes) or is it a single elevation line along its path?
Is the source line an open feature or a closed feature?

Typically when you know the source line geometry and the desired output, the settings to define the required approach to generate the correct output should be relatively straight forward to work out. The key to success is to have a set of Slope Designer Styles and Point Creator Settings that define all of the variable requirements that you may have and then just select and apply those as needed for each task that you encounter.

Offset Slope and Offset Elevation Styles
In these types of slope design the computed line will be offset horizontally and offset vertically using an Elevation, Elevation Delta or a Slope. The points on the source line that really matter are the Horizontal Nodes and the Vertical Nodes of the source line. Creating points at intervals along the line only matters in curved sections, along straight sections as long as you create nodes where the line changes direction or where it has a vertical grade break or where a vertical curve starts, ends, at its high point and at intervals through a vertical curve you will create a good offset line that does what you require. Setting up a point creator style that does this will give you the best results. If your offset lines are for model building, then for curved sections you should use the Curve to Chord setting and put in a tight tolerance e.g. 0.01 or 0.02 for it to compute the chording through the arcs (and spirals) that will generate a nice 3D line for modeling purposes. Note that if you use the Optimize function, the line once computed will be optimized to turn the chords back into 3D curvilinear geometry including arcs to generate the best possible result. Optimizing the curved sections of lines will prepare the created line for further offsets derived from its geometry, ideal for chaining together a series of design offset lines i.e. you may do an offset at 0% to create a setback line and then a 4’ vertical wall followed by a 2:1 sideslope to final grade surface when designing a footing.

Below are screen grabs of the Point Creator Settings that we recommend for Offset Slope and Offset Elevation type slope designs

Horizontal Locations



Vertical Locations



Note if your source lines include vertical arcs or vertical curves then you will need to add the intervals along the straight and curve sections in order to pick up the vertical shape of the vertical curves - use an interval of 2.5 or 5.0’. I would recommend using the Optimize function when doing this, that way the line will first be computed accurately and secondly optimized to minimize the number of nodes and elevation points along the line.

Use Case Tip:

If your source line includes curve geometry, if you are creating a vertical wall (near vertical) then use an offset of 0.02’ to allow the optimizer to best fit the curves into the lines created and not cause your created lines to get too close to each other for vertical face modeling purposes.

Slope to Surface and Slope to Elevation Styles
In these types of sideslope, there are a few things to consider

  • Sideslopes that are computed to create the daylight line with the target surface will need frequent intervals along the source line in order to compute the daylight line accurately. The more intervals you create the more accurately your daylight line will be calculated. You will need intervals along straight sections, around curved sections and additionally through vertical curve sections as well as all of the key points in the source line including Start, End, Corners, Tangent Points, Grade Break Points etc.

  • When doing slope to elevation type designs, you need to take into account the vertical geometry of your source line. If the vertical geometry includes grade breaks then you need to compute your offset lines at those locations. If your source line includes curves, then you need to compute at intervals (use Curve to Chord method to compute these). If your source line includes vertical curves then for this type of slope design you do not need to compute through the vertical curve unless you are using the delta elevation option.

  • In both cases, Slope Designer now supports both positive and negative cuts and fills. A cut by default is a positive slope and a fill is a negative slope, however in some scenarios you may wish to create a negative cut or a positive fill. Enter the negative sign for fill slopes and on cut slopes where appropriate.

Horizontal Locations

Vertical Locations

Computation mode:
The point / line computation methods available are selectable from the computation mode pulldown list. The methods available are as follows

Offset - Elevation
Offset - Slope
Slope - Elevation
Slope - Surface

Elevation mode:
When you select Offset - Elevation or Slope - Elevation mode, you can then select the elevation mode i.e. Delta or Absolute elevation.

Note: The slope data can be entered as a percentage slope e.g. -2% or as a ratio e.g. 2:1. Note you need to enter the sign of the slope when it is downwards i.e. a negative slope.


Note: The dialog changes to reflect the data entry method selected, allowing for input of the selected values and in an appropriate order for the selected data entry method.

Internal corner mode:
An internal corner is a corner where the angle is less than 180 degrees. An external corner has an angle greater than 180 degrees. i.e. for a line that has a right angle corner that bends to the right, the internal corner will be on the right side of the line and the external corner on the left side of the line.

The slope designer command has a number of “smart improvements” for handling internal corners. There are several potential solutions to how an internal corner point is created as described below. At an internal corner the traditional offset slope solution creates a “shoelace” effect at the corner as shown here

for any given or computed offset, the blue line at the internal corner has two perpendicular computations that cause the shoelace effect. The pink line represents the area for the given offsets and given interior angle that is a “no go” zone. The intersection of the two offset lines (inbound and outbound), is the point at which you typically want to compute the interior corner point.

The following diagram shows the different options

Intersection mode:
This is the default mode used to compute an internal corner.

The alternative way to compute the interior corner point is to use the angle bisector method. This projects both the inbound and outbound offset line segments onto the bisector of the internal angle. This generates two possible points at which the interior corner point could be. The closest and the farthest points. The third option is to use the average of the two locations. Note that depending on whether the source line has constant or variable elevations and whether the offset line is being computed at a constant offset or at a variable offset (slope to elevation, slope to surface or using a range function (see below) where the range creates a variable offset), will often dictate which method you should utilize to solve each scenario. Our recommendation is to use Intersection mode until you find a situation where one of the other methods will provide a value benefit.

Chamfer mode:
This mode was added to better support the modeling of surfaces for curb and gutter machines. These machines require a surface model that is computed from the source line (curb) with offset lines at 10’ to the inside and 2’ to the outside of the source line, both at 0% cross slope. At an internal corner where the curb has varied elevations through the corner, the internal corner point computed using e.g. Intersection mode creates a hybrid elevation at the internal corner which causes the cross slope of the surface to change. The chamfer corner creates two points at the internal corner on a short chamfer and also connects the ends of the chamfer to the corner point on the source line - thereby holding the 0% cross slope all the way into the corner - but creating a step in elevation over the short distance of the chamfer.

Average mode:
This is half way between the Closest and Farthest solution

Closest mode:
This is the point at which the closest line segment crosses the bisector line

Farthest mode:
This is the point at which the farthest line segment crosses the bisector line

Note: The elevation of the intersection point is computed in the following way

Intersection Point Mode - Uses the average value of the elevations of the two intersecting lines
Average Point Mode - uses the average elevation of the closest and farthest values
Closest Point Mode - uses the closest point elevation
Farthest Point Mode - uses the farthest point elevation

External corner mode:
On an exterior corner, the corner can be computed in one of three ways. The methods offered depend on the computation mode selected

In the chamfer mode. the command computes the two right angle points to the inbound and outbound lines, and then connects them directly across the corner creating a chamfer effect.

In the radial mode, the command computes the two right angle points to the inbound and outbound lines, and then subdivides the corner angle into a number of bisectors and computes a radial point along each bisector to form the offset line around the corner. The number of radial points is computed automatically using the curve to chord settings for horizontal curves in the point creator settings based on the offset distance. In the Slope to Surface and Slope to Elevation modes, the curve to chord computation is based on the largest radius offset at the start or end of the corner sweep - this creates the highest number of radial bisectors to generate the best daylight line at the corners

Tangential Extension:
In the tangential extension mode, the command projects the inbound line and the outbound line tangentially to their point of intersection with the corner bisector line and computes a single point at the corner.

Note the internal or external corner projections will be created when you select or include the corner point of the reference line using Single, All or Range Serial or Range Parallel Station modes. For all other station interval locations a single projection point will be computed at all locations and intervals defined by the Location styles settings (Point Creator Settings).

Location styles:
The locations along the reference line (start, end, nodes) can be supplemented using manually selected stations along the line when computing the slope design manually, however in the Add all locations or automated mode, the start, end and node locations can be supplemented using the location styles function. The location styles function shares the same definitions as those defined for the RPS Point Creator command (Click Here for more details of the way that these settings are defined and used).

These settings control where additional points will be created along the reference line when you use the All or Range Serial or Range Parallel Station mode (see below).

For example you may want to generate additional nodes at regular intervals along straight or curved sections of the reference line or at all VPI locations along the line through vertical curves and grade breaks etc.

Depending on the Station mode that you select (see below) the Offset, Elevation and Slope fields will provide the following styles of input

All or Single Station Mode
These modes provide a single data entry for Offset and Slope or Offset and Elevation / Delta Elevation

Range Serial or Range Parallel Mode
These modes provide a dual data entry for Offset and Slope, Elevation or Delta Elevation at Start Station and End Station as defined in the fields below where you select the Reference Line and the Station mode.

When you use the station range modes the offset and elevation, delta elevation and slope values will vary in a linear manner between the start and end station values selected. If the source line is curved within the range selected then the curvature is accounted for in the offset line created.

Enter the offset value(s) when required. The offset value is always entered as a positive number, the side of the line is defined lower down in the dialog.

Enter the elevation or delta elevation value(s) when required.

Enter the slope value when required. Note that when you select the Slope - Elevation or Slope - Surface data entry method you can define both a cut and fill slope if required, such that when the reference line is above or below the target elevation or target surface the appropriate cut or fill slope can be determined. Cut slopes point up and fill slopes point down. Enter side slopes (Slope to Surface or Slope to Elevation) as either positive or negative values. The default data entry is using a slope ratio, you can enter e.g. 25% to create a 4:1 slope. All values are stored and recalled as ratios from the style settings file. Slopes in Offset - Slope modes are entered as positive or negative values depending on what you require.

Select the target surface when required from the surface selector pull down list. The target surface is used in the Slope - Surface mode only. Target surface now also supports Reference Surfaces (TBC v5.60).

Reference line:
Select the source or reference line for the command to process. The points and lines will be created at a defined offset, elevation, delta elevation, slope etc. and at user selected or automatically selected stations along the selected reference line.

Show line direction toggle switch:

The show line direction is a toggle button at the end of the line selection field. Click the button to enable the show line direction function to show direction indicators on the selected line to identify which side of the line is the left or right side. The button will have an orange tinge when enabled.

Select the radio button for the side of the line on which to compute the offset points and lines i.e. Left or Right. You can use the R key to toggle Left to Right or Right to Left when the Station field is active.

Station mode:
The command supports four different modes of operation as follows

  • Single
  • Range - Parallel
  • Range - Serial
  • All

Single mode:
In this mode, you can click anywhere along the source line to generate a single point offset at the desired slope, elevation, delta elevation etc. You can click in any station order along the source line at any time. If you are creating lines, the lines will simply insert new segments on each click and will update the line being created with each node that you add, regardless of the order of entry. If you click a node along the source line then the appropriate corner mode will be applied to generate points and or lines around the corner area. You can change the offset, slope, elevation or delta elevation values at any time and the updated values will be used on the next click. In this way you can create offset points and or lines with variable slopes and elevations as required by the design information provided.

Range - Parallel mode:
Use this mode to create multiple offset lines over the same range from a common source line. Each time you click apply will create a new line within the station range defined.

Note: when you use the Range option and create a station range that uses the start point of the alignment or the end point of the alignment, you may need to tap apply to create the line you are working on.

Range - Serial mode:
Use this mode to create multiple lines over adjacent or separated station ranges along the source line. Each time you click apply will create a new line within the station range defined, after which the start station will be adjusted automatically to the end station of the previously created line.

Note: when you use the Range option and create a station range that uses the start point of the alignment or the end point of the alignment, you may need to tap apply to create the line you are working on.

All mode:
Use this mode to create a single line over the entire station range of the source line.

Start Station:
Enter a Station value or select a station location along the reference line, from which the point / line node will be computed using the other entered values. You can create locations at any station at any time and in any order, allowing you to compute additional locations when needed. use Near line snap and End snap etc. to select specific locations along the reference line. When you select a node (corner point) the internal or external corner projections will be computed.

End Station:
When you select the Range - Serial or Range - Parallel mode you can select both a start station and enter the end station value here.

Auto apply on station change checkbox:
If you wish the command to automatically create the point / line node on clicking or entering a station value or end station value (in Range modes), check this checkbox. When left unchecked you will need to click the Apply button to create the point or line node. When checked, you can click anywhere along the line to add an extra node.

If you click beyond the current ends of the reference line no line node or point will be created.

Use Case Notes

When using a defined Style, you can vary the slope or elevation values used by the command, they are not updated in the defined style until you click the save button in the style selector.

When you are working in All or Range station modes, each time that you click apply or click the end station location / value, the line will be created and a new line initiated automatically.

If you switch from Left to Right side of the line, a new line is not automatically created, allowing you to facilitate the creation of a crossing line

Click the New button to end the existing offset line and start a new line. On clicking New the Reference line field will be highlighted allowing you to start a second process from the same line or select a new reference line for the creation of the new line.

To create a point or line node when the Auto apply on station change checkbox is unchecked click the Apply button.

To close the command tap the Close button.

RPS Settings:
In the header of the command pane, you will find the RPS Settings button. Click this button to access the RPS Settings controls that may affect this command.

Commands in the header:
You will find a number of standard TBC commands in the header of the Slope Designer command. These include

  • RPS Settings
  • Join
  • Break
  • Offset line
  • Create surface
  • Add / Remove surface members
  • Copy
  • Change elevation
  • Edit linestring

Use Case Videos

The following videos show the use of the Slope Designer command in a work process context

Feedback and Enhancement Requests

If you would like to provide feedback on the use of the Slope Designer command or to request enhancements or improvements to the command please click “Reply” below


The following video shows how to use Slope Designer to compute Wetland Area Offset Lines at 100’ offset with radial sweep external corners to minimize the limit areas for structural construction. The customer request stated that the offset line takes too much area because it does a perpendicular offset with projected tangential extensions on external corners - this can take too much land - in addition with complex shape wetlands, you have a lot of tidying up on the linework to do - Slope Designer makes light work of the problem.