Expand string to DTM surface

You can use this function to make a copy of a selected string and expand or contract all segments of the string. You can project the segments of the string up or down using a surface to determine the target elevations. You can also choose to project the string a fraction of the height between the points on the selected string and the surface. You can use a maximum bench height and limiting elevation to ensure that the expanded segments do not exceed a maximum bench height and design elevation of interest.

Prerequisites: A surface is open in Graphics.

To run this function: Choose Design > Expand string > To DTM surface, or...

In the Function Chooser, type EXPAND STRING TO DTM, and press ENTER.

Fields on the Expand string to a DTM form

Field	Description
String	Display only. The string number of the selected string.
Minimum Z value	Display only. The minimum Z value of the selected string.
Maximum Z value	Display only. The maximum Z value of the selected string.
Define the method of expansion
% of height to DTM	The percentage of the distance to the DTM that the points of the string are projected. To ensure that each point on the selected string achieves the elevation of the surface in the new string, type a value of 100. If you want the new string to progress only a fraction of the distance to the surface, enter the appropriate percentage. For example type 50 to progress half of the distance to the surface, or 25 to progress one quarter of the distance to the surface.
Maximum bench height	The maximum bench height you can mine to. The projection of the selected string towards the surface can result in a design which is unacceptable for the type of mining equipment which is used. This can be due to unacceptably high benches resulting in dangerous mining conditions. You can restrict the bench heights to ensure that they do not exceed a pre-determined maximum limit by entering the maximum bench height here. If you do not want to limit bench height, use a high value such as 9999. Note: The maximum bench height is always a positive value.
Z direction	You can determine whether the points on the selected string are projected up to the surface or down to the surface. Up: The position of any points which are currently above the surface will be the same in the new string. Down: The position of any points which are currently below the surface will be the same in the new string. to DTM: Any points that are currently below the surface are projected up to the surface, and any points that are currently above the surface are projected down to the surface. Consequently the new string will represent the toe of fill and the crest of cut based entirely on the relative positions of the points in the selected string with respect to the surface. This option is particularly useful when the selected segment represents the outline of a roadway because the result that is produced represents the extent of the cut and fill required for the road.
Limiting Elevation	The limiting elevation restricts the elevations of the points on the new string. If, for each point on the selected string, the elevation of the new position for that point (after considering the surface, percentage of height to surface and the maximum bench height) would exceed the limiting elevation, the new position for the point is changed so that it is less than or equal to the limiting elevation.
Horizontal direction	expand: The selected string is expanded to create the new string. contract: The selected string is contracted to create the new string.

Output

All segments of the selected string are copied and modified according the values described above. The new segments are drawn in Graphics. Any loops that may form as a result of contracting portions of the segments are removed. The number of the new string is the number after the number of the selected string. Before calculating the positions of the points on the new string, the selected string is examined with respect to the surface and new points are introduced where the string is found to pass through (from above to below, or below to above) the surface. This will ensure that a clean transition from cut to fill is achieved especially when using the Z direction of 'to dtm'.

Expand string to DTM surface

Fields on the Expand string to a DTM form

Output

Troubleshooting