Real-time kinematic (RTK) drone images contain metadata fields of recorded accuracy and orientation information that can be used by ArcGIS Drone2Map to adjust the output products. Post-processed kinematic (PPK) drone images also contain the same metadata information, usually stored as an external file to be used when importing the images into ArcGIS Drone2Map.
Both RTK and PPK drones can provide highly accurate output imagery products once processed. However, for the highest possible accuracy, it is also recommended that you incorporate ground control as check points into the project. Additional steps can be incorporated into either workflow to achieve the greatest success.
Import RTK or PPK drone imagery
Processing images from an RTK or PPK drone in Drone2Map starts with the image import step.
Import RTK drone imagery
To import RTK drone imagery, complete the following steps:
- Open ArcGIS Drone2Map.
- Choose a processing template.
- Click Add Images to add individual images to the project, or click Add Folder to add a folder of images to the project.
- Select the images or folder and click OK.
The images will import and appear in the image table with listed basic metadata.
Import PPK drone imagery
PPK drone images require a few additional steps compared to RTK images, but the process is quite similar.
To import PPK drone imagery, complete the following steps:
- Open ArcGIS Drone2Map.
- Choose a processing template.
- Click Add Images to add individual images to the project, or click Add Folder to add a folder of images to the project.
The images will import and appear in the image table with listed basic metadata.
- Click Create to create the project.
- On the Flight Data tab, under the geolocation group, click the GPS Source button.
The Set GPS Source window appears.
- Click Import to display GPS import options.
- Click the Browse button.
- Browse to the PPK metadata file and click OK.
PPK metadata files can be in TXT, CSV or MRK format. PPK collected images require that you run those images through special software to obtain the metadata file that is used to provide Drone2Map with image information. ArcGIS Drone2Map does not support the handling of PPK corrections, only the interpretation of the output metadata file.
- Use the drop-down choices to configure the GPS field information to match the correct metadata fields from the imported file.
- Click OK.
The project imagery is updated to use the new PPK file instead of the image metadata.
Configure image coordinate system
The image coordinate system represents the coordinate systems that the drone uses to geotag each drone image location. Most RTK drones record the image locations in the geographic coordinate system WGS 1984 and use the ellipsoid height (also typically WGS 1984) to measure the drone’s altitude. However, it is important to verify the correct image coordinate system with the drone manufacturer and base station before processing images in Drone2Map.
To configure the image coordinate system after importing RTK or PPK imagery, complete the following steps:
- Click the Image Coordinate System button.
The spatial reference window appears with the x,y coordinate system selected.
- Use the search box or expand the available x,y coordinate system options to find the desired system.
If you are using a custom coordinate system or your own coordinate system file, this can be imported from the Add Coordinate System drop-down menu.
- Click the Current Z tile.
- Use the search box or expand the available z-coordinate system options to find the desired system.
- Click OK.
Import check points
The prospect of being able to create high-accuracy products without the need for collecting GCPs is arguably the most appealing benefit of RTK or PPK drones. While it is possible to create high-accuracy 2D and 3D products from an RTK or PPK drone without using GCPs, consider that without check points, there is no way to validate the accuracy of the products. Therefore, using check points remains an essential component of the RTK or PPK workflow.
Note:
To avoid transformation errors between geographic datums, it is highly recommended that the control points are collected in a projected coordinate system within the same geographic coordinate system as the RTK or PPK drone imagery.
To import check points at project creation, complete the following steps:
- Import either RTK or PPK imagery on the New Project page.
- Click the Import Control button.
The Import Control window appears.
- Browse to a control point file and select it.
- Click OK.
The control points will be imported and added to the control feature class when the project is created. The project coordinate system will default to be the same as the control so it is important to know what coordinate system you want in the output results. For further information on how to link control points as check points, see Manage control.
Configure project coordinate system
The project coordinate system is the coordinate system of the 2D and 3D products after processing is complete. Drone2Map creates output products in the same coordinate system as the imported control. If you have already imported control points, there is no need to set the project coordinate system. If you have not imported control points, use the project coordinate system settings to define the project coordinate system.
To configure the project coordinate system after importing RTK or PPK imagery, complete the following steps:
- Click the Project Coordinate System button.
The spatial reference window appears with the x,y coordinate system selected.
- Use the search box or expand the available x,y coordinate system options to find the desired system.
If you are using a custom coordinate system or your own coordinate system file, this can be imported from the Add Coordinate System drop-down menu.
- Click the Current Z tile.
- Use the search box or expand the available z-coordinate system options to find the desired system.
- Click OK.
Specify a transformation
If the image coordinate system and the project coordinate system are based on different geographic datums, a transformation between the two is needed. Drone2Map automatically selects a default transformation when needed. However, more than one transformation may exist, such as when transforming from ellipsoid heights to orthometric heights. For example, when selecting NAVD88 as the project vertical coordinate system, you can select the desired geoid model (Drone2Map 2023.2 and later), such as GEOID12B or GEOID18.
Note:
Not all transformations are shipped with Drone2Map, and downloading and installing ArcGIS Coordinate Systems Data is recommended.
Transformations are applied after projects are created through the following workflow:
- From the Home tab, under the processing group, click the Options button.
The options window appears.
- Click the Coordinate systems tab.
- Use the Select Transformation drop-down menu to select the desired transformation.
If the adjustment step has already been run in the project then all coordinate system changes will be locked. The project processing steps will need to be reset to access the options again. This can be done through the Project Data tab of the options window.
Enable high-accuracy GPS
Drone2Map has a processing option called Fix Image Location for High Accuracy GPS (RTK and PPK) that fully uses the high accuracy GPS capabilities of RTK or PPK drones. When this option is checked, Drone2Map will not attempt to optimize the location of image positions during the Adjust Images step. This ensures that the images’ locations collected by the RTK or PPK drone stay fixed during the adjustment.
Configure the project for high accuracy GPS by completing the following steps:
- From the Home tab, under the processing group, click the Options button.
The options window appears.
- Click the Adjust Images tab.
- Check the box for Fix Image Location for High Accuracy GPS (RTK and PPK).
The Fix Image Location for High Accuracy GPS option should not be used with ground control points as it may distort accuracy values. A warning will appear before processing if the option is checked and ground control points are currently linked within the project.
- Click Apply.
- Click OK to close the window.
Taking the time to configure and understand the data with RTK and PPK projects helps produce the best output results. By using this workflow, you can lower the chance of running into issues. For tips and more information on RTK and PPK troubleshooting, see Real-time kinematic data collection