An analysis of Convolutional Long Short-Term Memory Recurrent Neural Networks for gesture recognition

In this research, we analyze a Convolutional Long Short-Term Memory Recurrent Neural Network (CNNLSTM) in the context of gesture recognition. CNNLSTMs are able to successfully learn gestures of varying duration and complexity. For this reason, we analyze the architecture by presenting a qualitative evaluation of the model, based on the visualization of the internal representations of the convolutional layers and on the examination of the temporal classification outputs at a frame level, in order to check if they match the cognitive perception of a gesture. We show that CNNLSTM learns the temporal evolution of the gestures classifying correctly their meaningful part, known as Kendon's stroke phase. With the visualization, for which we use the deconvolution process that maps specific feature map activations to original image pixels, we show that the network learns to detect the most intense body motion. Finally, we show that CNNLSTM outperforms both plain CNN and LSTM in gesture recognition. (C) 2017 The Authors. Published by Elsevier B.V.