Object Detection Using Deep CNNs Trained on Synthetic Images

TL;DR

This paper demonstrates that effective object detection CNNs can be trained primarily on synthetic images with transfer learning, reducing the need for large annotated real datasets, and achieves promising results in refrigerator food product detection.

Contribution

It introduces a method for training CNNs on synthetic data for object detection, showing high performance with minimal real images and analyzing factors influencing transfer learning success.

Findings

4000 synthetic images achieve 24 mAP on test set

Adding 400 real images increases mAP by 12%

High photorealism in synthetic images is not essential

Abstract

The need for large annotated image datasets for training Convolutional Neural Networks (CNNs) has been a significant impediment for their adoption in computer vision applications. We show that with transfer learning an effective object detector can be trained almost entirely on synthetically rendered datasets. We apply this strategy for detecting pack- aged food products clustered in refrigerator scenes. Our CNN trained only with 4000 synthetic images achieves mean average precision (mAP) of 24 on a test set with 55 distinct products as objects of interest and 17 distractor objects. A further increase of 12% in the mAP is obtained by adding only 400 real images to these 4000 synthetic images in the training set. A high degree of photorealism in the synthetic images was not essential in achieving this performance. We analyze factors like training data set size and 3D model dictionary size for their influence on detection performance. Additionally, training strategies like fine-tuning with selected layers and early stopping which affect transfer learning from synthetic scenes to real scenes are explored. Training CNNs with synthetic datasets is a novel application of high-performance computing and a promising approach for object detection applications in domains where there is a dearth of large annotated image data.