  In large technology companies, the requirements for managing and organizing
technical documents created by engineers and managers have increased
dramatically in recent years, which has led to a higher demand for more
scalable, accurate, and automated document classification. Prior studies have
only focused on processing text for classification, whereas technical documents
often contain multimodal information. To leverage multimodal information for
document classification to improve the model performance, this paper presents a
novel multimodal deep learning architecture, TechDoc, which utilizes three
types of information, including natural language texts and descriptive images
within documents and the associations among the documents. The architecture
synthesizes the convolutional neural network, recurrent neural network, and
graph neural network through an integrated training process. We applied the
architecture to a large multimodal technical document database and trained the
model for classifying documents based on the hierarchical International Patent
Classification system. Our results show that TechDoc presents a greater
classification accuracy than the unimodal methods and other state-of-the-art
benchmarks. The trained model can potentially be scaled to millions of
real-world multimodal technical documents, which is useful for data and
knowledge management in large technology companies and organizations.
