To be able to apply the techniques on georeferencing images taken from UAV and generate products like DEM and Orthomosaic photo.
For this exercise, the sample data used was taken from the Olympic Village in Munich.
To start the georeferencing process, all the twenty (20)images were loaded into Agisoft Metashape using the Import Photos tool. Since we know the camera accuracy for these images, we can set it to 5 cm before importing.
After loading the images, we can then choose to optimize camera, adjust some image settings, as well as work with the generated sparse point cloud. To improve the quality of the sparse point cloud, the Gradual Selection Tool was used. The Reprojection Error threshold was set to 0.7, while Reconstruction Uncertainty threshold was set to 85. The selected points were then deleted from the display.
After this, the provided GCP was imported as well. The columns were not properly defined on the text file so the right order of the columns was fixed before the export as shown in the image below. This way, each attribute will align on the corresponding column (lat, long, altitude, etc.)
After importing the location of the GCP, the proper location of each individual GCP was examined on every image. A corresponding marker was placed for a specific GCP if its visible on an image. This was facilitated for all the 20 images. Below are some screenshots taken during the placing of markers for every image.
The sparse point cloud was updated by running the Optimize Camera tool again once the markers were placed on the respective locations. Now that the sparse point cloud is ready, the Build Dense Point Cloud tool was used to generate the Dense Point Cloud. For the quality, I only chose Medium so it will not take too much time processing and generating the dense point cloud.
Once the Dense Point Cloud was generated, other products such as Digital Elevation Model and Orthomosaic can be generated as well.
The Build DEM tool was used to make the DEM with the Dense Point Cloud as the source layer.
The same resolution (0.15m) was used to make the Orthomosaic photo using the Build Orthomosaic tool.
To check the quality of the generated DEM and Orthomosaic, both raster layers are exported as TIF.
The raster layers were then imported to ArcGIS Pro. Using the Satellite Imagery basemap, both the DEM and Orthomosaic were examined if they are aligning perfectly with the basemap. Upon checking the images thoroughly, both are perfectly lining up with the satellite image, as shown in the images below.
