Available with 3D Analyst license.
Measuring 3D straight-line distances between points of interest allows you to perform operations such as finding the shortest distance between two points. This could be the shortest distance between points on the globe surface or the shortest distance between a point on the globe surface and a 3D feature, such as a window on a building. Also, this can be used to find the shortest distance between two points of interest floating independently of the globe surface, for example, the distance between two windows in separate buildings.
To measure the straight-line distance in 3D, you can use the Measure Direct 3D Line tool 
on the Measure dialog box. Measuring straight-line distances in 3D can be thought of as measuring about a pivotal point using a rope.
- Click the Measure
tool on the Tools toolbar.
- Click the Measure Direct 3D Line tool .
- Click the location where you want to start measuring the 3D distance.
- Move the pointer to the point of interest and click to start measuring the 3D distance. If you would like to continue measuring a straight 3D line, move the pointer to another location and click to add vertices.
- Double-click when you want to end the line.
- Optionally, while measuring, if you want to navigate around to see the measurement from a different perspective view, you can either:
- Press the ESC key once. This pauses the measure sketch. You can then press and hold SPACE to navigate in the globe. This can be useful after you are done measuring and want to define the view differently—for example, taking a screen capture. If you are in the middle of your sketch, press TAB to resume the measure from where you left off.
- Press and hold SPACE without pausing the graphic and dynamically begin to navigate and modify the view's perspective. You can zoom in/out, pan, and tilt as you would with the Navigate tool. When you release SPACE your sketch will resume wherever your pointer is, so your results may not be as expected or as controlled as if you had paused the sketch first.
The 3D distance between the last two points of interest, along with the total 3D distance from the starting point, is displayed in the Measure window.