Mapping Walls of Indoor Environment using RGB-D Sensor

Inferring walls configuration of indoor environment could help robot "understand" the environment better. This allows the robot to execute a task that involves inter-room navigation, such as picking an object in the kitchen. In this paper, we present a method to inferring walls configuration from a moving RGB-D sensor. Our goal is to combine a simple wall configuration model and fast wall detection method in order to get a system that works online, is real-time, and does not need a Manhattan World assumption. We tested our preliminary work, i.e. wall detection and measurement from moving RGB-D sensor, with MIT Stata Center Dataset. The performance of our method is reported in terms of accuracy and speed of execution.

Comparison of Modified Kneser-Ney and Witten-Bell Smoothing Techniques in Statistical Language Model of Bahasa Indonesia

Smoothing is one technique to overcome data sparsity in statistical language model. Although in its mathematical definition there is no explicit dependency upon specific natural language, different natures of natural languages result in different effects of smoothing techniques. This is true for Russian language as shown by Whittaker (1998). In this paper, We compared Modified Kneser-Ney and Witten-Bell smoothing techniques in statistical language model of Bahasa Indonesia. We used train sets of totally 22M words that we extracted from Indonesian version of Wikipedia. As far as we know, this is the largest train set used to build statistical language model for Bahasa Indonesia. The experiments with 3-gram, 5-gram, and 7-gram showed that Modified Kneser-Ney consistently outperforms Witten-Bell smoothing technique in term of perplexity values. It is interesting to note that our experiments showed 5-gram model for Modified Kneser-Ney smoothing technique outperforms that of 7-gram. Meanwhile, Witten-Bell smoothing is consistently improving over the increase of n-gram order.