PDM¶

class
menpofit.modelinstance.
PDM
(data, max_n_components=None)[source]¶ Bases:
ModelInstance
Class for building a Point Distribution Model. It is a specialised version of
ModelInstance
for use with spatial data. Parameters
data (list of menpo.shape.PointCloud or menpo.model.PCAModel instance) – If a list of menpo.shape.PointCloud, then a menpo.model.PCAModel will be trained from those training shapes. Otherwise, a trained menpo.model.PCAModel instance can be provided.
max_n_components (int or
None
, optional) – The maximum number of components that the model will keep. IfNone
, then all the components will be kept.

as_vector
(**kwargs)¶ Returns a flattened representation of the object as a single vector.
 Returns
vector ((N,) ndarray) – The core representation of the object, flattened into a single vector. Note that this is always a view back on to the original object, but is not writable.

copy
()¶ Generate an efficient copy of this object.
Note that Numpy arrays and other Copyable objects on
self
will be deeply copied. Dictionaries and sets will be shallow copied, and everything else will be assigned (no copy will be made).Classes that store state other than numpy arrays and immutable types should overwrite this method to ensure all state is copied.
 Returns
type(self)
– A copy of this object

d_dp
(points)[source]¶ Returns the Jacobian of the similarity model reshaped in order to have the standard Jacobian shape, i.e.
(n_points, n_weights, n_dims)
which maps to(n_features, n_components, n_dims)
on the linear model. Returns
jacobian (
(n_features, n_components, n_dims)
ndarray) – The Jacobian of the model in the standard Jacobian shape.

from_vector
(vector)¶ Build a new instance of the object from it’s vectorized state.
self
is used to fill out the missing state required to rebuild a full object from it’s standardized flattened state. This is the default implementation, which is which is adeepcopy
of the object followed by a call tofrom_vector_inplace()
. This method can be overridden for a performance benefit if desired. Parameters
vector (
(n_parameters,)
ndarray) – Flattened representation of the object. Returns
object (
type(self)
) – An new instance of this class.

from_vector_inplace
(vector)¶ Deprecated. Use the nonmutating API, from_vector.
For internal usage in performancesensitive spots, see _from_vector_inplace()
 Parameters
vector (
(n_parameters,)
ndarray) – Flattened representation of this object

has_nan_values
()¶ Tests if the vectorized form of the object contains
nan
values or not. This is particularly useful for objects with unknown values that have been mapped tonan
values. Returns
has_nan_values (bool) – If the vectorized object contains
nan
values.

increment
(shapes, n_shapes=None, forgetting_factor=1.0, max_n_components=None, verbose=False)[source]¶ Update the eigenvectors, eigenvalues and mean vector of this model by performing incremental PCA on the given samples.
 Parameters
shapes (list of menpo.shape.PointCloud) – List of new shapes to update the model from.
n_shapes (int or
None
, optional) – If int, then shapes must be an iterator that yields n_shapes. IfNone
, then shapes has to be a list (so we know how large the data matrix needs to be).forgetting_factor (
[0.0, 1.0]
float, optional) – Forgetting factor that weights the relative contribution of new samples vs old samples. If 1.0, all samples are weighted equally and, hence, the results is the exact same as performing batch PCA on the concatenated list of old and new simples. If <1.0, more emphasis is put on the new samples. See [1] for details.max_n_components (int or
None
, optional) – The maximum number of components that the model will keep. IfNone
, then all the components will be kept.verbose (bool, optional) – If
True
, then information about the progress will be printed.
References
 1
D. Ross, J. Lim, R.S. Lin, M.H. Yang. “Incremental Learning for Robust Visual Tracking”. International Journal on Computer Vision, 2007.

set_target
(new_target)¶ Update this object so that it attempts to recreate the
new_target
. Parameters
new_target (PointCloud) – The new target that this object should try and regenerate.

property
n_active_components
¶ The number of components currently in use on this model.
 Type
int

property
n_dims
¶ The number of dimensions of the spatial instance of the model
 Type
int

property
n_parameters
¶ The length of the vector that this object produces.
 Type
int

property
n_weights
¶ The number of parameters in the linear model.
 Type
int

property
target
¶ The current menpo.shape.PointCloud that this object produces.
 Type
menpo.shape.PointCloud

property
weights
¶ The weights of the model.
 Type
(n_weights,)
ndarray