KEPLER: Keypoint and Pose Estimation of Unconstrained Faces by Learning Efficient H-CNN Regressors

Keypoint detection is one of the most importantpre-processing steps in tasks such as face modeling, recognitionand verification. In this paper, we present an iterative methodfor Keypoint Estimation and Pose prediction of unconstrainedfaces by Learning Efficient H-CNN Regressors (KEPLER) foraddressing the face alignment problem. Recent state of the artmethods have shown improvements in face keypoint detectionby employing Convolution Neural Networks (CNNs). Althougha simple feed forward neural network can learn the mappingbetween input and output spaces, it cannot learn the inherentstructural dependencies. We present a novel architecture calledH-CNN (Heatmap-CNN) which captures structured global andlocal features and thus favors accurate keypoint detecion. H-CNNis jointly trained on the visibility, fiducials and 3D-pose of theface. As the iterations proceed, the error decreases making thegradients small and thus requiring efficient training of DCNNs tomitigate this. KEPLER performs global corrections in pose andfiducials for the first four iterations followed by local correctionsin a subsequent stage. As a by-product, KEPLER also provides3D pose (pitch, yaw and roll) of the face accurately. In thispaper, we show that without using any 3D information, KEPLERoutperforms state of the art methods for alignment on challengingdatasets such as AFW [38] and AFLW [17].