# An Image-Based Fall Detection System for the Elderly
## 5 Experiment
### Test Cases: Other Situations  
For the other situations, there are three tests: sitting on a bench with no seatback, squatting, and a high-angle shot. Apart from when lying on the floor, the top of the person is still higher than the top of the bench with no seatback. For that, if IFADS detects the object as the bench, then it considers the height of the bench as twice that. Then, we test when the tester is sitting on the bench with no seatback, and falls off the bench with no seatback, while sitting on the bench and standing up from the bench. Figure 13 shows the results of the bench with no seatback. In Case 1, the tester walks to the bench, sits down, and walks away. In Case 2, the tester walks to the bench, sits down, and falls while sitting down. In Case 3, the tester walks to the bench, sits, and falls while standing up from the bench. The results in Figure 13 show that IFADS detects correctly even with a bench with no seatback.  
Figure 12: The test results of the effect of the person–chair ratio on IFADS’s accuracy.  
Figure 13: The results of the bench with no seatback test cases.  
Squatting may cause a fault in IFADS detection. Figure 14 shows the illustration of the squatting cases. We test when the tester squats when far from the chair and when beside the chair for more than 3 s. Case 1 and Case 2 both show that the tester squats when far from the chair; the tester has his/her back to the camera in Case 1, and faces the camera in Case 2. Case 3 to Case 7 all show that the tester squats. Both Case 3 and Case 4 show that the tester squats when beside the chair; the tester has his/her back to the camera in Case 3, and faces the camera in Case 4. The tester squats in front of the chair, behind the chair, and while facing the chair in Cases 5, 6, and 7, respectively. Figure 15 shows the results of the squatting test cases. In Case 1 and Case 2, a fall is detected, since the height of the tester is less than 5.5/8 times the tester's height 1.5 s before and the tester maintains the state for more than 3 s. In the other cases in Figure 15, the tester squats when beside the chair. The tester is detected as a falling person in Case 3 and Case 7, since he bends his back more. The tester is not detected as a falling person in the other cases, since he keeps his back straight more. As mentioned, squatting may cause a fault in IFADS detection. However, it is dangerous for the elderly to squat for more than 3 s, since the elderly face muscle loss.  
For a high-angle shot, the tester may cause a fault in IFADS detection, since the height of the person that IFADS detects may be wrong. Figure 16 shows the illustration of the difference between the common situation and a high-angle shot. We test when the tester walks across (in front of or behind) the chair, sits on the chair, and falls. Figure 17 shows the test results of the high-angle shot. IFADS detects the fall correctly, because it detects the fall by the change of the person's height and state.  
Figure 14: An illustration of the squatting cases.  
Figure 16: An illustration of a common situation and a high-angle shot.  
Figure 15: The results of the squatting test cases.