The rarity of nitrogen (N)-fixing trees in frequently N-limited higher-latitude (here, > 35°) forests is a central biogeochemical paradox. One hypothesis for their rarity is that evolutionary constraints limit N-fixing tree diversity, preventing N-fixing species from filling available niches in higher-latitude forests. Here, we test this hypothesis using data from the USA and Mexico. N-fixing t...

We describe a generative model of ‘talking head’ facial behaviour, intended for use in both video synthesis and model-based interpretation. The model is learnt, without supervision, from talking head video, parameterised by tracking with an Active Appearance Model (AAM). We present a integrated probabilistic framework for capturing both the short-term visual dynamics and longer-term behavioural...

One of the major drawbacks of the Active Appearance Model (AAM) is that it requires a training set of pseudo-dense correspondences. Most methods for automatic correspondence finding involve a groupwise model building process which optimises over all images in the training sequence simultaneously. In this work, we pose the problem of correspondence finding as an adaptive template tracking proces...

Appearance variations result in many difficulties in face image analysis. To deal with this challenge, we present a Unified Tensor-based Active Appearance Model (UT-AAM) for jointly modelling the geometry and texture information of 2D faces. For each type of face information, namely shape and texture, we construct a unified tensor model capturing all relevant appearance variations. This contras...