  There has been an increasing interest in deploying non-line-of-sight (NLOS)
imaging systems for recovering objects behind an obstacle. Existing solutions
generally pre-calibrate the system before scanning the hidden objects. Onsite
adjustments of the occluder, object and scanning pattern require
re-calibration. We present an online calibration technique that directly
decouples the acquired transients at onsite scanning into the LOS and hidden
components. We use the former to directly (re)calibrate the system upon changes
of scene/obstacle configurations, scanning regions, and scanning patterns
whereas the latter for hidden object recovery via spatial, frequency or
learning based techniques. Our technique avoids using auxiliary calibration
apparatus such as mirrors or checkerboards and supports both laboratory
validations and real-world deployments.
