  Region-based object detection infers object regions for one or more
categories in an image. Due to the recent advances in deep learning and region
proposal methods, object detectors based on convolutional neural networks
(CNNs) have been flourishing and provided the promising detection results.
However, the detection accuracy is degraded often because of the low
discriminability of object CNN features caused by occlusions and inaccurate
region proposals. In this paper, we therefore propose a region decomposition
and assembly detector (R-DAD) for more accurate object detection.
  In the proposed R-DAD, we first decompose an object region into multiple
small regions. To capture an entire appearance and part details of the object
jointly, we extract CNN features within the whole object region and decomposed
regions. We then learn the semantic relations between the object and its parts
by combining the multi-region features stage by stage with region assembly
blocks, and use the combined and high-level semantic features for the object
classification and localization. In addition, for more accurate region
proposals, we propose a multi-scale proposal layer that can generate object
proposals of various scales. We integrate the R-DAD into several feature
extractors, and prove the distinct performance improvement on PASCAL07/12 and
MSCOCO18 compared to the recent convolutional detectors.
