  This work presents an extrinsic parameter estimation algorithm between a 3D
LIDAR and a Projective Camera using a marker-less planar target, by exploiting
Planar Surface Point to Plane and Planar Edge Point to back-projected Plane
geometric constraints. The proposed method uses the data collected by placing
the planar board at different poses in the common field of view of the LIDAR
and the Camera. The steps include, detection of the target and the edges of the
target in LIDAR and Camera frames, matching the detected planes and lines
across both the sensing modalities and finally solving a cost function formed
by the aforementioned geometric constraints that link the features detected in
both the LIDAR and the Camera using non-linear least squares. We have
extensively validated our algorithm using two Basler Cameras, Velodyne VLP-32
and Ouster OS1 LIDARs.
