class_docstr: Default validation transform for AlphaPose.
  
  Parameters
  ----------
  num_joints : int
      Number of joints defined by dataset
  joint_pairs: list
      Paired Joints for horizontal flipping
  image_size : tuple of int
      Image size, as (height, width).
  sigma : float
      Gaussian sigma for the heatmap generation.
code: def __init__(
      self, num_joints, joint_pairs, image_size=(256, 256), sigma=1
  ):
      self._sigma = sigma
      self._num_joints = num_joints
      self._joint_pairs = joint_pairs
      self._image_size = image_size
      self._height = image_size[0]
      self._width = image_size[1]
      self._aspect_ratio = float(self._width) / self._height
  
file_path: gluon-cv/gluoncv/data/transforms/presets/alpha_pose.py
imports: from __future__ import absolute_import
  import random
  import numpy
  import mxnet
  from ..pose import random_sample_bbox, count_visible, random_crop_bbox
  from ..pose import drawGaussian, transformBox, cv_cropBox, cv_rotate, detector_to_alpha_pose
label_desc: Use image node_id 1 to create a new AlphaPoseDefaultValTransform object from inherited base classes: object with example: obj = AlphaPoseDefaultValTransform(num_joints, joint_pairs, image_size, sigma)