# Review of Photogrammetric and Lidar Applications of UAV
## 6 Discussion
### Discussion on Applications of UAVs
#### 6.2.1 Mapping and Surveying
The software environment used for data processing was Riscan Pro v.1.6.1 and Agisoft PhotoScan v.1.0.4. The Resulting 3D model and 3D point cloud were generated. The authors of the article [102] explored a concept for weighted data fusion that can enhance the 3D mapping transmitted by a UAV using a camera and a lightweight line laser scanner. The research used a UAV with a Hokuyo UTM-30 LX-EW sensor and a GoPro 1080p HD HERO2. The measurements were made at the Karlsruhe Palace in Germany. From the result, an accurate 3D model was created. The images had an estimated standard deviation of 0.44 pix, and the scanner was 12 cm. The research in the article [103] focused on using UAV for the 3D modeling of Tibetan architectural heritage. The area of interest is located in the monastery town of Gyantse (Tibet), and the surveyed building is the Auspicious Multi-Door Stupa. A DJI Phantom 4 with an integrated camera was used for the imaging. A TLS Leica ScanStation C10 laser scanner with a Canon 60D external camera was also used. A total of 55 GCPs were taken at this location and determined by the total station. After SfM processing, the resulting RMSE had a vale of 2.05 cm/1615 pix. For the TLS, the RMSE was 6 mm. A 3D model of the building was generated. The article [104] was devoted to research on applying oblique aerial photogrammetry. A resort hotel located in Mengyuan area, China, was selected for this research. The UAV DJI Mavic 2 Pro was used and controlled using the Pix4D capture application. Data were processed in Autodesk ReCap software to create a 3D model of the hotel. The author of the article [105] discussed architectural heritage documentation using low-cost UAVs with a fisheye lens. The measurement location was The Otag-i Humayun, Turkey. The UAV used was a 3 DR Solo UAV with a 12 Mpix GoPro Hero 4 sensor. Only 28 images were captured, at a height of 50 m AGL. When five GCP were also deployed, the result was a RMSE value of 3.1 cm. As a result, the 3D point cloud, DSM, ortho-mosaic, and a 3D solid model were created. The authors of the article [106] discussed research on monitoring and 3D documentation of architectural heritage using UAV. The equipment contained ISTI-CNR UAV with Ximea XiQ high-speed camera, and Canon EOS M (18 Mpix) was used. Agisoft Photoscan, COLMAP, and Autodesk ReCap software were used for 3D reconstruction. Accuracy was achieved within a few tenths of a millimeter. To accurately assess the architectural features of the peach trees at Washington State University's Tukey Horticultural Orchard, both a UAV with an integrated RGB camera and a lidar system were used for reference [107]. Photogrammetric data were acquired using three flights at a flight height of 15 m AGL, with an overlap of 80%. A DJI Phantom 4 Pro UAV with an integrated 20 Mpix RGB camera was deployed. The resulting GSD reached an average value of 0.49 cm. Lidar data were acquired using a UAV on which a VLP 16 Velodyne lidar was placed. The Pix4 Dmapper software was used to create a 3D point cloud, a digital surface model (DSM), a digital terrain model (DTM), and ortho-mosaics. In architecture, the use of UAV photogrammetry is especially suitable. Compared to classical methods using total stations and lidar methods, they have the advantage of almost complete coverage of the measured object. The realistic phototexture of the resulting model is also a great advantage.