The Calculate Cross option allows to create a series of sections by laying down cut lines which are perpendicular to a user defined centre line.
When selected, the property sheet asking you to define the section cut lines will be displayed.
The Definition page allows you to define the position of the section centre line together with the length and spacing of the cross sections. When calculating cross sections, the No Empty Sections allows you to ignore cross section cut lines that do not create any profiles.
The Chainage field allows you to define the start chainage of the centre line. This is used to change the distance from the start point to where the first cut line is generated. If you enter a start chainage of 5m and an interval of 20m, the first section will be generated 15m along the centre line. The chainage value is also used to name the sections.
The radio buttons allow you to define the method by which you will specify the centre line position.
Sketch - Each point on the centre line is defined by using the mouse cursor. This option will follow the current lock mode setting.
Points - Each point on the centre line is defined by an existing point in the current model.
Feature - The location of the centre line is defined by the points of an existing line feature.
CAD Line - The location of the centre line is defined by a CAD polyline. The search will take place in the CAD models in the current backcloth or the CAD model associated with the current DTM.
Co-ordinates - The location of the start and end points of each cut line is stored in a co-ordinate block. You will be asked to select the block and each pair of points is used to create the cut lines. Note that for this option, there is no centre line.
Design String - The location of the centre line is defined by a design feature whose points have chainages, bearings and radii stored in dimensions CHN, BRG and RAD respectively.
Alignment - The location of the centre line is defined by an alignment that is stored in the current project. You will be asked to select the required alignment using a dialog box.
Since chainages are available for the last two options, the Chainage field is disabled and the value stored in the first point of the design string or the alignment start chainage is used as the initial chainage. With these options, the Decreasing check box is enabled and, if checked, allows you to generate sections that start at the end of the design string or alignment looking back up
For the last two options, the Selected Chainages check box is also enabled. This allows you to restrict the cross sections that are calculated to a specified chainage range using the dialog shown below.
The start and finish chainages are specified by selecting the required values in the two drop lists. For the design string option, the chainage on each point is added to each list whilst for the alignment option, the chainages from the current alignment settings are added.
The Left and Right offsets allow you to specify the offsets of the start and end points of the cut lines from the centre line. The sum of these two values represents the length of each cut-line. The convention for both values is positive to the left or right whichever offset is being defined. It is possible to enter zero or negative offsets in a situation where you wish the cross sections to be wholly one side of the defined centre-line. The Interval field allows you to specify the spacing of the cut lines.
You should note that if you are using cut lines from a co-ordinate block, the offset and interval values are meaningless as the start and end positions do not need to be calculated.