Detecting text in floor maps using Histogram of Oriented Gradients

Automatic detection of text labels in maps is essential for applications requiring automatic map understanding. This task is challenging due to factors such as varying font size and style, slanted words/phrases, and interfering graphics that are similar to text. This paper presents an approach for text detection in indoor floor maps. We exploit the difference in spatial frequency of edge orientations between text and non-text regions through Histogram of Oriented Gradients (HOG) features, and design a gradient-filtered Support Vector Machine (SVM) classifier based on such features. Special care was taken in conditioning the data for proper training of the classifier. The proposed approach was evaluated on a data set that had been collected and manually labeled. Experimental results show that the proposed method attained improved performance, outperforming a couple of reference methods/systems.