Topography

Source file: topography-group.htm

The Topography group tools enable you to draw lines that identify and highlight topographic detail on scans and surfaces.

	Contours (Alt+K) Create elevation contour lines on surfaces.
	Toes and Crests Create bench toe and crest lines .
	Sections Create section lines on surfaces at regular intervals.
	Surface Boundaries (`Alt`+`\`) Draw boundary edges of surfaces.
	Elevation Profile Draw the elevation profile of a line, such as a haul road centreline.
	Join Points Create a line joining points in a selection.

Contours

The Contours tool (Alt+K) allows you to create contours on surfaces, which are then saved into an edge network object.

To create contours, do the following:
1. Select at least one surface from which to create contour lines.
2. On the Create tab, in the Topography group, click Contours.
3. Enter the Upper limit and Lower limit for the contour creation, or click on them in the view window.
4. Select the Step major contours from checkbox and enter a datum value to generate contours from a level other than the zero RL. Clear to generate contours from the zero RL.
5. Define the Interval and Colour for the major contours.
6. Select the Label contours checkbox and define a Label size and Density of labels (ideally the same size as the interval) to add elevation labels to the major contours.
7. Select the Minor contours checkbox to generate minor contour lines between the major contours. Specify a Minor interval and Colour.
8. Select a container for the created contours object in the Destination field. By default, the contours are saved in the contours container.

Example contours

Major and minor contours, with the major contours labelled.

Toes and Crests

The Toes and Crests tools allow you to draw breaklines lines on scans. You can do this can in two stages, as described below.

Expand for detail.

Preliminary toes and crests

Create preliminary toes and crests determines and creates breaklines as loops or edge networks automatically from a triangulation.

Tip: Best results are achieved using a fusion surface to create a triangulation with an even distribution. See Fusion Surface.

Select the relevant surface.

Note: Do not use a simplified surface.
Apply a uniform colour to the surface. See Uniform.
On the Create tab, go to the Topography group. From the Toes and Crests drop-down list, select Preliminary.
Select a facet on a bench or other near-horizontal area on the surface. The tool will calculate and display lines representing toes and crests by identifying all connected facets not exceeding the defined Intersection angle, then creating a polygon around them.

Tip: Press 0 to make the line thicker and more visible.
Adjust the angle to achieve the best result.

Tip: Increase the intersection angle to create lines higher up walls and cross obstructions.
Click Apply.
To cover areas that have been missed, click in the Bench facet field, then repeat steps 4-6 for each area.
Once all preliminary toes and crests are created, exit the tool.

The preliminary toes and crests are saved in the cad container in a secondary container named toes and crests of <surface name>.

Preliminary toes and crests are sorted into two containers named recommended and other:

recommended contains the results considered to be the most accurate.
other contains results that may be of use. These results are colour coded from red to green, indicating the level of confidence.

Tip: You can use smart lines to fill in any areas that are not clearly defined by preliminary toes and crests. See Smart Line.

Drag any lines to be kept from the other container to the recommended container. Delete the rest.
Edit any incorrect line segments by selecting their points and pressing Delete.

Actual and ideal toes and crests

Use Actual and Ideal to generate actual and ideal toe and crest lines as edge networks from an initial set of preliminary toe and crest lines (see above).

On the Create tab, go to the Topography group. From the Toes and Crest drop-down list select Actual and Ideal.
Select one of the Toe and crest lines options:
- Actual: Generates lines that share points along the preliminary toe and crest edges, fitting the original data. Lines created are regularly sampled such that they have an approximate point spacing of the value specified on the dialog box.
- Ideal: Generates lines that better fit the surface. The toe lines will be pushed in, under the rill, towards where the ideal toe lines should be if a batter was just cut. Similarly, the crest lines will be pulled out, towards where the ideal crest lines would be if parts of the batter had not fallen down creating the rill. The pit can be a triangulation, a point set or a scan. This option will perform better on objects with higher point densities.
- Actual and Ideal: Generates both actual and ideal toe and crest lines as above.
The default colour for toe lines is green, and for crest lines is red. If required, select different colours from the colour swatches.
Drag the recommended container (see Preliminary toes and crests) into the Preliminary toes and crests field.
You can add Guide lines to assist in classifying actual and ideal toe and crest lines. These guide lines also assist in fitting ideal toes and crests. Guide lines can be any lines, usually created with the Draw Line tool, and should be drawn to define creases and bends in the surface to generate better fitting ideal toe and crest lines.
Enter the Approximate point spacing to define the level of detail to be applied to the lines.
Clear the Split toes and crests into separate objects checkbox to create the toes and crests as a single object. Leave selected to create separate objects.
If generating ideal toe and crest lines, drag appropriate data into the Fit toes and crests to field. This data can consist of any object type. However, scans or surfaces are recommended.
Click Apply or OK.

PointStudio generates the chosen toe and crest lines and places them in a new container named actual or ideal inside the toes and crests of <surface name> container.

Actual toes and crests (left) and ideal toes and crests (right). Crests are red and toes are green.

Sections

The Sections drop-down provides tools for creating sections that you can use to compare surfaces. Expand below for detail on each sectioning tool.

Parallel Sections

Parallel sections are always in the same orientation, so are best used in relatively straight sections of tunnel.

Create parallel sections as follows:

Select the scans to be sectioned.
On the Create tab, in the Topography group, click Parallel Sections (Alt+/).
In the Section line area, select one of the options for defining the section line, then enter details according to the following:
- Vector: Enter the Start sections at and End sections at coordinates, or pick the start and end points in the view window.
- Edge chain: Select an edge chain in the project explorer or view window.
In the Sections defined by area, select either Distance or Amount, then enter the required distance between sections or the number of sections to be created.
Choose from the following Sectioning options:
- Select Merge section lines into a single object to create a single edge network representing the parallel section of the object.
- Select Flatten section lines to the XY plane to create edge networks restricted to the XY plane, without any elevation.
- Select Make sectioning planes vertical to create edge networks in planes parallel with the Z axis.
Enter the required Destination container or leave it as default.
Click OK or Apply. The parallel sections are saved as lines in the container specified at step 6.

The above example compares two sections from the same surface overlaid to show changes in the surface.

Surface Boundaries

The Surface Boundaries tool creates edge networks that define the boundaries of a surface.

To create a surface boundary:
1. On the Create tab, in the Topography group, click Surface Boundaries. Alternatively, on the Query tab, in the Boundary group, click Surface Boundaries.
2. With Merge boundaries into a single object either:
  - Select to include all loops in a single edge network.
  - Clear to create the edge loops as separate objects.
3. Click OK or Apply to finish.


Surface boundaries have been created as a single edge network (left) and as edge loops (right). Edges are represented in green and holes in the surface are represented in red.

Elevation Profile

The Elevation Profile tool unwraps a line so that all its points lie in a single vertical plane without changing Z values.

This is helpful, for example, for evaluating the elevation profile of a haul road. i.e. elevation against horizontal distance.

To create an elevation profile:

Select the subject line , such as the centreline of a haul road.
On the Create tab, in the Topography group, click Elevation Profile.
The elevation profile line will be placed in the cad container and named unwrapped line of subject line name.

An unwrapped line (left), tiled and tied to the original line from which it was generated (right).

The same unwrapped line viewed from above (left), tiled and tied to the original line from which it was generated (right).

Join Points

The Join Points tool joins a selection of points to create a line following user-defined indexing.

This enables you to quickly and automatically create an edge chain based on existing data, instead of creating an edge chain manually.

Data used can consist of either single-point or multi-point objects. Expand below for details on each.

Data consists of single-point objects only

Single-point objects can be any of the following:

Annotations
Survey points
Point sets containing only one point
Scans with only a single point

The tool will create a single edge chain across all selected objects.

The following indexing options are available for single point objects:

Position in data explorer. The line will be drawn through points in their order of appearance in the project explorer.

In the example below, the line will be drawn as follows:

	First point in the line will be the point from `another_point`
	Next point in the line will be at `point`
	Next point in the line will be at `Text Demo 2`
	The final point in the line will be at `scan_with_one_point`

This is useful if you sequentially named a set of survey points, and sorted them accordingly. You can then easily create an edge chain from the survey points.

Object tag. The edge chain is created through points ordered by the value of a specified object tag. Objects in the selection without the specified tag are ignored.

This method is useful with multiple scans that cover an area. Tag values can be applied to points in different scans to put them in order before using the Join Points tool. .
Point tag. This works similarly to the Object tags method, but uses the value of the point tag of individual points from the object, rather than from the object as a whole. Objects in the selection without the specified tag are ignored.

For instructions on creating tags, see Create Attributes.

To join points using attributes:

Select the objects with points to be joined in the project explorer.
On the Create tab, in the Topography group, click Join Points.
From the Index by drop-down, select the option that was used to create the attribute.
Select the tag denoting points to be joined from the Using drop-down.
Click OK or Apply.

All points in the selected object, with the chosen tag will be joined.