Measurement Tools

The following measurement tools are available:

§   Query

§   Distance  

§   Area

Measurements can display dynamically as well as be saved in the Project Tree as TerraExplorer objects.

Information Query

The Information Query tool provides you with data about any point or object in the 3D World. For a point on the terrain, location and elevation information is provided, while for an object, the query also displays the object’s perimeter and area. If the object selected was loaded from a layer with attribute information, the object’s attributes are also displayed.

 To use the information query tool:

1.       On the Analysis tab, in the Measurement group, click Query. 

2.       Move the cursor over any point in the 3D Window. When you move the cursor over an object, the object is highlighted.

3.       Click on the point or object for which you require information.

§   In the Message Bar, TerraExplorer Pro displays the longitude, latitude and altitude.

Note:   Military Grid Reference System (MGRS) coordinates are also displayed if Show MGRS Coordinates was selected in the Options dialog box. See “View” in the “Using TerraExplorer Options” chapter for more information.

§   The Query Results dialog box is displayed, showing the longitude, latitude, and elevation. When an object is selected, general information about the object and attribute information, if available, is displayed.

4.       With the Information Query tool selected, you can click again on any point in the terrain to find its coordinates. Repeat for as many points as you wish.

5.       On the Analysis tab, in the Measurement group, click Query again to close the Information Query.

Distance Tool

The Distance tool measures aerial, horizontal and vertical distance and slope between two or more points. You can also calculate and display the terrain elevation profile for the aerial measurement line.

 To use the distance tool:

1.       On the Analysis tab, in the Measurement group, click Distance. The Distance Measurement dialog box is displayed with the following distance options:

§   Create Measurement Objects – Select the check box if you want to create measurement objects that will be accessible from the Measurement Objects folder in the Project Tree.

§   Show Aerial Distance – Show a yellow line marking the aerial distance, i.e., the actual distance between points, in the 3D Window. The aerial distance is calculated and displayed in the Distance Measurement dialog box even if this option is not selected.

§   Show Horizontal Distance – Show a white line marking the horizontal distance between points in the 3D Window. The horizontal distance is calculated and displayed in the Distance Measurement dialog box even if this option is not selected.

§   Show Vertical Distance – Show a purple line marking the vertical distance between points in the 3D Window. The vertical distance is calculated and displayed in the Distance Measurement dialog box even if this option is not selected.

 

Distance Measurement

2.       If you want to change measurement units, click the Units link. The Options dialog box is displayed, showing the View tab. Modify the display options for Altitude and Distance and Measurement, and then click OK. See “View” in the “Using TerraExplorer Options” chapter for more information.

3.       If you want to snap the measurement points to an object’s edge or vertex, click Snap Based on Snapping Options . TerraExplorer automatically detects all edges, i.e., intersections of two plane faces, and vertices, i.e., intersections of two polylines.

4.       In the 3D Window, click any point on the terrain or on an object to define the start point of the measurement. A yellow line extends from the start point. Drag the cursor to the next point and click again. Repeat to add as many segments as required. If you want to delete the last point added, click Delete Point .

5.       Right-click to finish the measurement.

6.       If you want to obtain the same measurement type between any two or more points in the terrain, with the Distance command selected, repeat steps 2-5 above.

The Distance dialog box displays the following measurements:

Measurement	Description
Total Aerial Distance	The aerial distance, i.e., the actual distance between the points. This measurement is the sum of the aerial distances between the points as you progress from the start point to the endpoint.
Total Horizontal Distance	The horizontal distance between the points. This measurement is the sum of the horizontal distances between the points as you progress from the start point to the endpoint.
Total Vertical Distance	The difference in elevation between the points. If you have marked more than two points, this measurement does not take into account the elevation values of the middle points.
Slope	The slope of the line between the first and last points. If you have marked more than two points, this measurement does not take into account anything other than the elevation at the start point and the elevation at the endpoint.

7.       If you want to delete the measurement polyline in the 3D Window, click Delete .

8.       If you want to display the terrain elevation profile along the drawn line, and related information such as maximum and minimum elevation values and slope, do the following:

a.       Click Terrain Profile . A terrain profile graph opens, displaying the terrain elevation profile.

Terrain Profile Graph

b.       Use the Zoom in , Zoom out , and Zoom to full extent of data  buttons to adjust the zoom as required.

c.       Determine what information is indicated on the graph by selecting any of the following display options:

Waypoint	Select the check box to mark each of the polylines' waypoints on the graph with a .
Min/Max Elevation	Select the check box to mark each of the polylines' maximum and minimum points with a .
Min/Max Slope	Select the check box to mark each of the polylines' maximum and minimum slope with a .

d.       If you want to export the terrain profile to a shapefile layer, click Export to Layer.

e.       Point to any point on the graph to display the following values. If you want to display the values and jump to the point on the terrain, then click instead of pointing.

Value	Description
X	X-coordinate of the selected point.
Y	Y-coordinate of the selected point.
MGRS	The coordinates of the selected point converted to Military Grid Reference System (MGRS) coordinates. This field is only available if Show MGRS Coordinates was selected in the Options dialog box. See “View” in the “Using TerraExplorer Options” chapter for more information.
Elevation	Elevation value of the point above the terrain database vertical datum base ellipsoid.
Slope	Slope of the curve at the selected point

Area Tool

The Area tool allows you to calculate area on the terrain or on an arbitrary plane.

 To use the area tool:

1.       On the Analysis tab, in the Measurement group, click Area. The Area Measurement dialog box is displayed.

Area Measurement Dialog Box

2.       Click either of the following commands:

§   Horizontal plane area (2D measurement)  - Calculate area on terrain. The area measured is the horizontal projection of the area you have outlined, even if some or all your selected area encompasses mountainous terrain.

§   3D plane area  - Calculate area on an arbitrary plane.   The polygon’s orientation is determined by the first three points selected.

3.       If you want to save the measurement in the Project Tree as a TerraExplorer object, select Create Measurement Objects.

4.       If you want to change measurement units, click the Units link. The Options dialog box is displayed, showing the View tab. Modify the display options for Altitude and Distance and Measurement, and then click OK. See “View” in the “Using TerraExplorer Options” chapter for more information.

5.       If you want to snap the measurement points to an object’s edge or vertex, click Snap Based on Snapping Options . TerraExplorer automatically detects all edges, i.e., intersections of two plane faces, and vertices, i.e., intersections of two polylines. See "Setting Snapping Options" in the "Working with Objects" chapter for more information.

6.       In the 3D Window, click any point on the terrain/plane to define the start point of the measurement. Click to set the second point and then again for each additional point. Right-click to finish the measurement. If the boundary line of the measured area crosses itself, it turns red. If you want to delete the last point added, click Delete Point .

7.       Right-click to finish the measurement. The Area dialog box displays area and perimeter measurements.

8.       If you want to calculate the surface area of the selected region taking into account terrain contours, do the following:

a.       In the Surface Sample Interval field, type the desired distance between terrain sample points.

b.       Click Terrain Surface Area (3D measurement) . The terrain surface area measurement is displayed.

9.       If you want to delete the area polygon in the 3D Window, click Delete .