The Image Measurement widget allows you to perform measurements on image services with mensuration capability. Mensuration is a method of applying geometric rules to find length of lines, area of surfaces, or volume using information obtained from lines and angles. It can also include measuring the height and absolute location of a feature.
Any image service with a georeferenced raster dataset can provide distance, area, point, and centroid locations. Height measurements can be obtained when a sensor model exists. Sun angle information is required to make measurements using shadows.
Configuring the Image Measurement widget
The Image Measurement widget can be set to open automatically when an app starts. To do so, click the dot on the widget to turn it dark green.
- Hover over the widget and click the small edit icon
. The configuration window for this widget opens. - Optionally, click the change widget icon button and replace it with your own image. A file explorer window opens, allowing you to choose a local image file to use as the widget icon.
- The Select measure operations field allows you to choose the different measure operations to be included in the widget. The options are as follows:
- Point
- Distance and Angle
- Area and Perimeter
- Centroid
- Base to Top
- Top to Top-Shadow
- Base to Top-Shadow
- Point (3D)
- Distance and Angle (3D)
- Area and Perimeter (3D)
- Centroid (3D)
- The Default Angular Unit parameter allows you to configure a pre-selected unit of measure for angular measurement. The options are as follows:
- Degrees
- Radians
- The Default Linear Unit parameter allows you to configure a pre-selected unit of measure for linear measurement. The options are as follows:
- Inches
- Feet
- Yards
- Miles
- Nautical Miles
- Millimeters
- Centimeters
- Decimeters
- Meters
- Kilometers
- The Default Area Unit parameter allows you to configure a pre-selected unit of measure for area measurement. The options are as follows:
- Inches
- Sq Inches
- Sq Feet
- Sq Yards
- Acres
- Sq Miles
- Sq Millimeters
- Sq Centimeters
- Sq Decimeters
- Sq Meters
- Ares
- Hectares
- The Display measure results in a pop-up check box allows you to choose whether you want to display the measurement in a pop-up window or within the measure widget. Click OK to close the dialog box when you're finished.
Using the Image Measurement widget
- Verify that you are signed in to your organization with privileges to perform image measurement. Click the widget icon in your app to open the widget panel.
- Click the Point Measurement icon and click a point on the map. The measurement widget displays the coordinates for the point.
- Click the Distance and Angle measurement icon and draw a line on the map. The widget displays the total distance and the azimuth angle in the units set in the widget. The units can be changed by accessing the options from the settings drop-down list.
- Click the Area and Perimeter measurement icon and draw a polygon around the area of interest using two or more clicks. The widget displays the total area and the perimeter in the units set in the widget.
- Click the Centroid measurement icon and draw a polygon using two or more clicks to create an area of interest (AOI). The widget will then display the coordinates of the centroid.
- The Base to Top tool calculates the height of a structure by measuring from the base of the structure to the top of the structure. Measurements are assumed to be perpendicular to the base. The line being measured along the building must have its end point directly above the start point.
- The Top to Top-Shadow tool calculates the height of a structure by measuring from the top of the structure to the top of the structure's shadow on the ground. The points on the structure and its shadow must represent the same point.
- The Base to Top-Shadow tool calculates the height of a structure by measuring from the base of the structure to the top of the structure's shadow on the ground. The point in the shadow must represent a point on the structure that is perpendicular to the base.
- Clicking the settings icon allows you to access the Measure 3D check box on the image services that support 3D measurement. You can use the Area and Perimeter, Centroid, and the height measurement tools in 3D mode. When the 3D mode is selected, it will use the DEM to refine the calculation.