Problem Description

You acquired a nadir aerial dataset and did not led a specific calibration step

You submitted an AT, the distortion parameters were computed and your photogroup oriented, but the result is not satisfying.
On that kind of dataset we often observe the same spherical deformation due to distortion parameters
inaccuracy.

Steps to Resolve

To avoid this problem, we recommend the following:

• Capture a small dataset of any object with the same camera
• Process an AT on this dataset by keeping the default settings
• Export the optical properties of the aero-triangulated photogroup
• Import these optical parameters in your "UAV-photogroup"
• Submit an AT and make sure to set the distortion parameters on "Keep" instead of "Adjust"
• The process will take advantage from these more accurate parameters and avoid the spherical effect.

Export optical properties

• Your camera distortion parameters are unknown
• Submitting an AT will provide you these parameters
• You can export them as an *.opt file by right-clicking on you aero-triangulated photogroup

Import optical properties

• You led a camera calibration, and you know accurately your camera's distortion parameters
• You can import them as an *.opt file by right-clicking on your photogroup, before submitting the AT

• Finally, in the AT settings, turn the default parameter on "Keep" in the distortion estimation properties.

See Also

 http://communities.bentley.com/products/3d_imaging_and_point_cloud_software/w/wiki/26457.how-to-calibrate-your-camera-using-contextcapture