tddfa_utils.py

import numpy as np


def similar_transform(pts3d, roi_box, size):
    pts3d[0, :] -= 1  # for Python compatibility
    pts3d[2, :] -= 1
    pts3d[1, :] = size - pts3d[1, :]

    sx, sy, ex, ey = roi_box
    scale_x = (ex - sx) / size
    scale_y = (ey - sy) / size
    pts3d[0, :] = pts3d[0, :] * scale_x + sx
    pts3d[1, :] = pts3d[1, :] * scale_y + sy
    s = (scale_x + scale_y) / 2
    pts3d[2, :] *= s
    pts3d[2, :] -= np.min(pts3d[2, :])

    return np.array(pts3d, dtype=np.float32)


def parse_param(param):
    """matrix pose form
    param: shape=(trans_dim+shape_dim+exp_dim,), i.e., 62 = 12 + 40 + 10
    """

    # pre-defined templates for parameter
    n = param.shape[0]
    if n == 62:
        trans_dim, shape_dim, exp_dim = 12, 40, 10
    elif n == 72:
        trans_dim, shape_dim, exp_dim = 12, 40, 20
    elif n == 141:
        trans_dim, shape_dim, exp_dim = 12, 100, 29
    else:
        raise Exception(f'Undefined templated param parsing rule')

    R_ = param[:trans_dim].reshape(3, -1)
    R = R_[:, :3]
    offset = R_[:, -1].reshape(3, 1)
    alpha_shp = param[trans_dim:trans_dim + shape_dim].reshape(-1, 1)
    alpha_exp = param[trans_dim + shape_dim:].reshape(-1, 1)

    return R, offset, alpha_shp, alpha_exp