X GCPs was 
criteria points 
mined by the 
Since it is 
S taken in the 
use an aerial 
aser scanning 
area and the 
y LPS. 
  
  
area of a new 
crash or other 
hich the UAV 
reen) is where 
f the locations 
^s on the final 
  
3. RESULTS AND DISCUSSION 
3.1 Performance of smartphone-based photogrammetric 
UAV system 
The automatic image-taking application is operated by Android 
OS-based smartphone. It was developed using Android 2.3 
SDK. This consisted of the beginning and end of automatic 
image-taking, calculation of image-taking interval, environment 
configuration, smartphone camera test and link test with 
bluetooth GPS (Figure 3). Environment configuration provides 
the screen to manage UAV name, camera option, automatic 
image-taking option and bluetooth GPS setting. The 
configuration of focus mode and white balance is performed in 
the camera option within environment configuration, and the 
location of image-taking and effective radius are set in the 
automatic image-taking option. 
5 E E NL 
UAVCamera S 
Cat env ue between alg photographs. 
| Tewbhewgthgs 0 
, SveMimigestowebsemer 
  
Figure 3. Screen for the implemented UAV photography system 
and field monitoring system application 
We fabricate vibration-proof devices because in case ordinary 
gimbal device is attached to the fixed wing platform, it is likely 
to do serious damage to the attached devices when UAV makes 
landing The frame for this device was designed to be attached 
directly to the platform using very light-weighted balsa (Figure 
4). 
monolibument 
23.3 mm 
  
  
  
  
  
  
  
  
balsa 
Figure 4. Vibration-proof device designed to reduce high- 
frequency vibrations in an electric glider. The smartphone is 
attached to the balsa framework with monofilament. 
    
3.2 Accuracy of Experiments 
3.2.1 Position accuracy 
In the static and dynamic experiments, 3D location information, 
3-axis attitude information and image were obtained from GPS 
built in smartphone, gyroscope and camera, respectively. The 
standard deviation in the location accuracy of GPS built in 
smartphone was 9.66m for the static experiment and 13.81m for 
the dynamic experiment. These results were similar to those 
from existing studies using MEMS sensors . 
3.2.2 Attitude accuracy 
Angular rate sensors have played an important role in aviation, 
space exploration and military applications. The heading angle 
provided by MEMS gyroscope in the static condition include 
the long-term bias drift, a slow-changing error source unlike the 
roll and pitch. The bias drift of the gyros is significant in 
MEMS-based systems and if left uncorrected can completely 
mask the navigation solution (Foxlin, 2005; Aggarwal et al., 
2011). 
3.2.3 Image block triangulation 
The first dynamic experiment was conducted with smartphone 
directly attached to the bottom of the fixed wing of UAV 
without using separate vibration-proof device. In this 
experiment, there occurred contortion in the images taken by 
smartphones due to the high-frequency vibration directly 
delivered from UAV. In particular, such contortion occurred 
most frequently in the images obtained by Galaxy S. In addition, 
as for the ortho-images converted from the images with rare 
contortion among the images obtained from Galaxy S2 through 
triangulation, there was a negative consequence that the image 
point's residual RMSE was large. 
Therefore, the image that best covers the test area for dynamic 
experiment was selected among those obtained from each 
smartphone. Using 12 images for Galaxy S and 8 images for 
both S2 type A and B, the image block was formed. 
   
   
  
200000 200:00 
301500 
301400