When processing unmanned aerial vehicle (UAV) data, it is recommended to use Two Pass: FBM and FFTPB for the automatic tie point collection method. This method automates point collection, refinement, and camera self-calibration for UAV data. When using this method it is recommended to use default values. Note that this method can also be used for scanned film air photos, but in this case camera self-calibration will not be performed.
To automatically collect TPs using Two Pass: FBM and FFTPB
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In the Matching channel box, enter the channel to use during collection.
Using the green channel, if it exists, usually produces the best results.
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In the Tie points per image box, type or select the number of TPs to collect on each image.
The higher the number, the more TPs OrthoEngine will attempt to collect, and the more processing time will be required. The actual number of collected TPs may be higher or lower than the number you specify.
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In the Alignment residual target box, type or select a value representing the threshold at which to reject tie points.
Note: The value is the residual of x and y per point, and not the RMS of all points.
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To remove unmodeled lens distortion, select the Perform camera self-calibration check box, and then below select whether to use All images or a Subset of images for camera self-calibration.
Note: When using a subset OrthoEngine will automatically select a block of highly connected images.
Note: Camera self-calibration is required when no external camera calibration has been provided, or if the provided external camera calibration is not accurate.
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To include tie points from the first pass (FBM) for final model refinement, select the Retain tie points from first pass check box.
Note: This option may be required if few points are retained after the Two Pass: FBM and FFTPB method completes, but it is not recommended for general use as the first pass tie points are meant for rough orientation.
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Proceed to Selecting images, start time, and run.