The Calculate Live option allows you to create a simple long section in the preview box. You are then given tools to move the cut line for the section in the graphic view of the DTM and the section preview windows will automatically update.
When selected, the property sheet asking you to define the section cut lines will be displayed. The Models page has already been described but you should note that live sections cannot be calculated through features and therefore only DTMs with formed triangles or grid DTMs can be chosen.
The Definition page allows you to define the type of live section that you wish to create using three radio buttons.
Sketch - You will be asked to indicate two locations that define the start and end of the section cut line. Unlike normal long sections, you will not be allowed to define more than two positions.
Feature - You will be asked to indicate an existing line feature and the live sections will always be calculated perpendicular to that feature.
Alignment - You will be asked to choose an alignment design and all live sections will always be calculated perpendicular to that alignment design.
For the latter two options, you will also need to define a length of section cut line in the Length field. The indicated line feature or alignment will be at the centre of the section with half the section length on either side.
Sketched Live Sections
If you select to create a sketched live section and the position of the cut line has been defined, the section is calculated and previewed in the normal way. Once the section is displayed, you can than change the section cut line by moving it in the graphic window using one of two methods. If you indicate the cut line within the last quarter of either end, you will be asked to indicate a new position for that end point and the preview will update. If you indicate the cut line within the central half, you will be asked to drag the cut line to a new position and again the preview will update. Note that the currently lock mode setting will be used.
Feature and Alignment Live Sections
If you select to create one of these live sections, you will be asked to graphically indicate the line feature to use or select the alignment to use in a dialog box. A section will then be calculated and displayed. The section will be perpendicular to the feature or alignment through its start point. To move the position of the section cut line, click the left mouse button anywhere in the preview window. As you move the mouse around, the cursor location will be projected onto the feature or alignment and a new cut line will be displayed. Once you are happy with the position, click the left mouse button and the new cut line will be fixed and the profile recalculated. Note that the currently lock mode setting will be used.
Leaving Live Sections
There are two methods that you can use to leave the current live section. If you select the right button on the mouse at any point, the live section preview window will be removed from the screen and the live section tool stopped. If you select the window close button in the live section preview window, you will be asked if you wish to save the current section. If you do, enter a name and select the OK button. If not, select the Cancel button and the section will be discarded. After this, the live section preview window will be removed and the live section tool stopped.