Use EasyVision to detect objects - Model Training| Alibaba Cloud Documentation Center

Machine Learning Platform for AI (PAI) provides EasyVision, which is an enhanced algorithm framework for visual intelligence. EasyVision provides a variety of features for model training and prediction. You can use EasyVision to train and apply computer vision models for your computer vision applications. This topic describes how to use EasyVision in Data Science Workshop (DSW) to detect objects.

Prerequisites

A development environment with the following software versions is prepared:

Python 2.7, or Python 3.4 or later
TensorFlow 1.8 or later, or PAI-TensorFlow

Note If you use a DSW instance, we recommend that you select an image of TensorFlow 1.12 and an instance type with a memory greater than 16 GiB.
ossutil is downloaded and installed. For more information, see Download and installation.

Notice After you download ossutil, you must set the endpoint parameter to oss-cn-zhangjiakou.aliyuncs.com in the configuration file.

Step 1: Prepare data

Use ossutil to download the Pascal dataset to the current directory.

./ossutil64  cp -r  oss://pai-vision-data-hz/data/voc0712_tfrecord/ data/voc0712_tfrecord

Download the ResNet50 pre-trained model to the current directory.

mkdir -p pretrained_models/
./ossutil64 cp -r oss://pai-vision-data-hz/pretrained_models/resnet_v1d_50/ pretrained_models/resnet_v1d_50

Step 2: Start a training task in the current directory

Single-machine mode
```
import easy_vision
easy_vision.train_and_evaluate(easy_vision.RFCN_SAMPLE_CONFIG)
```
In the training process, the model is evaluated every 5,000 rounds of training.

Multi-machine mode

You can use multiple servers to train the model. Make sure that each server has at least two GPUs. In multi-machine mode, you must start the following child processes:

ps: the parameter server.
master: the master that writes summaries, saves checkpoints, and periodically evaluates the model.
worker: the worker that processes specific data.

Run the following code to start a training task:

#-*- encoding:utf-8 -*-
import multiprocessing
import sys
import os
import easy_vision
import json
import logging
import subprocess
import time

# train config under distributed settings
config=easy_vision.RFCN_DISTRIBUTE_SAMPLE_CONFIG

# The configuration of the cluster. 
TF_CONFIG={'cluster':{
             'ps': ['localhost:12921'],
             'master': ['localhost:12922'],
             'worker': ['localhost:12923']
            }
          }

def job(task, gpu):
  task_name = task['type']
  # redirect python log and tf log to log_file_name
  # [logs/master.log, logs/worker.log, logs/ps.log]
  log_file_name = "logs/%s.log" % task_name

  TF_CONFIG['task'] = task
  os.environ['TF_CONFIG'] = json.dumps(TF_CONFIG)
  os.environ['CUDA_VISIBLE_DEVICES'] = gpu
  train_cmd = 'python -m easy_vision.python.train_eval --pipeline_config_path %s' % config
  logging.info('%s > %s 2>&1 ' % (train_cmd, log_file_name))
  with open(log_file_name, 'w') as lfile:
    return subprocess.Popen(train_cmd.split(' '), stdout= lfile, stderr=subprocess.STDOUT)


if __name__ == '__main__':
  procs = {}
  # start ps job on cpu
  task = {'type':'ps', 'index':0}
  procs['ps'] = job(task, '')
  # start master job on gpu 0
  task = {'type':'master', 'index':0}
  procs['master'] = job(task, '0')
  # start worker job on gpu 1
  task = {'type':'worker', 'index':0}
  procs['worker'] = job(task, '1')

  num_worker = 2
  for k, proc in procs.items():
    logging.info('%s pid: %d' %(k, proc.pid))

  task_failed = None
  task_finish_cnt = 0
  task_has_finished = {k:False for k in procs.keys()}
  while True:
    for k, proc in procs.items():
      if proc.poll() is None:
        if task_failed is not None:
          logging.error('task %s failed, %s quit' % (task_failed, k))
          proc.terminate()
          if k != 'ps':
            task_has_finished[k] = True
            task_finish_cnt += 1
          logging.info('task_finish_cnt %d' % task_finish_cnt)
      else:
        if not task_has_finished[k]:
          #process quit by itself
          if k != 'ps':
            task_finish_cnt += 1
            task_has_finished[k] = True
          logging.info('task_finish_cnt %d' % task_finish_cnt)
          if proc.returncode != 0:
            logging.error('%s failed' %k)
            task_failed = k
          else:
            logging.info('%s run successfuly' % k)

    if task_finish_cnt >= num_worker:
      break
    time.sleep(1)

Step 3: Use TensorBoard to monitor the training task

The checkpoints and event files of the model are saved in the directory in which pascal_resnet50_rfcn_model resides. You can use one of the following methods to view the loss and mean average precision (mAP) of the training:

Run the following command to obtain the logon link of TensorBoard. Then, open TensorBoard in a browser.

Notice You must run the command in Linux. To run the command, you must switch to the directory in which pascal_resnet50_rfcn_model resides, or replace the path following --logdir in the command with the actual path of pascal_resnet50_rfcn_model. Otherwise, the command fails to be run.
```
tensorboard --port 6006 --logdir pascal_resnet50_rfcn_model  [ --host 0.0.0.0 ]
```
In TensorBoard, you can view the following information:
- Training lossTensorBoard provides the following metrics about the training loss:
  - loss: the total loss of the training.
  - loss/loss/rcnn_cls: the classification loss.
  - loss/loss/rcnn_reg: the regression loss.
  - loss/loss/regularization_loss: the regularization loss.
  - loss/loss/rpn_cls: the classification loss of region proposal network (RPN).
  - loss/loss/rpn_reg: the regression loss of RPN.
- Test mAPPascalBoxes07 and PascalBoxes are used as metrics to calculate the test mAP, as shown in the preceding figure. PascalBoxes07 is commonly used in studies.
On the TensorBoard page, view information such as the loss and mAP of the training based on the instructions shown in the following figure.

Step 4: Test and evaluate the model

After the training task is complete, you can test and evaluate the trained model.

Use other datasets to test the model. Then, check the detection result of each image.
```
import easy_vision
test_filelist = 'path/to/filelist.txt' # each line is a image file path
detect_results = easy_vision.predict(easy_vision.RFCN_SAMPLE_CONFIG, test_filelist=test_filelist)
```
The detection result of each image is returned in the detect_results parameter in the format of [detection_boxes, box_probability, box_class]. In the format, detection_boxes and box_class indicate the location and category of the detected object. box_probability indicates the confidence level of the detection result.

Evaluate the trained model.

import easy_vision
eval_metrics = easy_vision.evaluate(easy_vision.RFCN_SAMPLE_CONFIG)

The eval_metrics parameter indicates evaluation metrics, including PascalBoxes07, PascalBoxes, global_step, and the following loss metrics: loss, loss/loss/rcnn_cls, loss/loss/rcnn_reg, loss/loss/rpn_cls, loss/loss/rpn_reg, and loss/loss/total_loss. The following examples show the metrics:

PascalBoxes07 Metric

PascalBoxes07_PerformanceByCategory/AP@0.5IOU/aeroplane = 0.74028647
PascalBoxes07_PerformanceByCategory/AP@0.5IOU/bicycle = 0.77216494
......
PascalBoxes07_PerformanceByCategory/AP@0.5IOU/train = 0.771075
PascalBoxes07_PerformanceByCategory/AP@0.5IOU/tvmonitor = 0.70221454
PascalBoxes07_Precision/mAP@0.5IOU = 0.6975172

PascalBoxes Metric

PascalBoxes_PerformanceByCategory/AP@0.5IOU/aeroplane = 0.7697732
PascalBoxes_PerformanceByCategory/AP@0.5IOU/bicycle = 0.80088705
......
PascalBoxes_PerformanceByCategory/AP@0.5IOU/train = 0.8002225
PascalBoxes_PerformanceByCategory/AP@0.5IOU/tvmonitor = 0.72775906
PascalBoxes_Precision/mAP@0.5IOU = 0.7182514

global_step and loss

global_step = 75000
loss = 0.51076376
loss/loss/rcnn_cls = 0.23392382
loss/loss/rcnn_reg = 0.12589474
loss/loss/rpn_cls = 0.13748208
loss/loss/rpn_reg = 0.013463326
loss/loss/total_loss = 0.51076376

Step 5: Export the model

Run the following code to export the model as a SavedModel file:

import easy_vision
easy_vision.export(export_dir, pipeline_config_path, checkpoint_path)

After you run the preceding code, a model directory is created in the export_dir directory. The name of the model directory contains the UNIX timestamp that indicates the time when the directory is created. All checkpoints of the model are exported to a SavedModel file in the model directory.

Step 6: Evaluate the SavedModel file

Run the following code to evaluate the exported SavedModel file. All metrics of the model are contained in the evaluation result file and logs.

from easy_vision.python.main import predictor_evaluate
predictor_evaluate(predictor_eval_config)

In the preceding code, predictor_eval_config specifies the .proto file that is used for the evaluation. For more information, see Protocol Documentation. You can also use the following files for evaluation:

detector_eval.config for object detection
text_detector_eval.config for text detection
text_recognizer_eval.config for text recognition
text_spotter_eval.config for end-to-end text recognition

Step 7: Deploy the model as a service

Save the SavedModel file in Object Storage Service (OSS) and use the file to deploy a service in Elastic Algorithm Service (EAS). For more information, see Create a Service.