GCP Matching - Falcon 8/8+/SIRIUS BASIC
- After all the initial AT processing for a given project has been completed, to improve the absolute accuracy of the data, ground control point (GCP) matching must be performed.
- Select the AT processed photo block (or merged block) from the left side of the screen and select the Surveys tab.
- Select Edit Control Points to open the Control point editor screen.
- On the Control points editor screen, from the drop down menu, select the spatial reference system for the control points to be used.
To add control points perform either of the two options listed below:
- Add control points by clicking the green + on the right and enter the coordinates manually.
Import coordinates from *.txt or *.csv by clicking File – Import.
- When importing from a *.txt or *.csv file, the file should be space delimited and be in Easting, Northing, Elevation (or Longitude, Latitude, Height)
- Select a control point from the created/imported GCP list and then select a corresponding image that contains the GCP target.
- Press Shift + Left click to measure the coordinates of the GCP target in the image.
Repeat this process for a minimum of 3 photos for a given GCP target and for a minimum of 3 GCP targets.
- For any GCP targets that will be used as a check point and not for transformation, check the Check Point checkbox for a given GCP.
- Once finished, select File – Save and exit the control points editor screen.
- After performing GCP matching for a given dataset, AT processing must be conducted again to apply changes.
- For the GCP matched block, select the General tab and select Submit Aerotriangulation.
- On the Output block name screen, enter a name for the new block to be created as necessary and select Next.
On the Positioning/georeferencing screen, select the following radio button:
- Use control points for adjustment – the block is accurately adjusted to control points (advised with accurate control points).
- Once finished, select Next.
On the Settings screen, leave all settings at their default values except for the following:
- Position: Adjust
- Rotation: Adjust
- Tangential Distortion: Adjust
- Once finished, select Submit to begin AT processing.
- Once AT processing has been completed, the horizontal/vertical accuracy and RMS values of the GCP matching can be viewed.
- Select the AT processed and GCP matched photo block from the left side of the screen and select the Surveys tab.
- Select Edit Control Points to open the Control point editor screen to view GCP matching metrics.
- Once finished, close the Control points editor screen.