Pose estimation is the task of using an ML model to estimate the pose of a person from an image or a video by estimating the spatial locations of key body joints (keypoints).
If you are new to TensorFlow Lite and are working with Android or iOS, explore the following example applications that can help you get started.
If you are familiar with the TensorFlow Lite APIs, download the starter MoveNet pose estimation model and supporting files.
If you want to try pose estimation on a web browser, check out the TensorFlow JS Demo.
How it works
Pose estimation refers to computer vision techniques that detect human figures in images and videos, so that one could determine, for example, where someone’s elbow shows up in an image. It is important to be aware of the fact that pose estimation merely estimates where key body joints are and does not recognize who is in an image or video.
The pose estimation models takes a processed camera image as the input and outputs information about keypoints. The keypoints detected are indexed by a part ID, with a confidence score between 0.0 and 1.0. The confidence score indicates the probability that a keypoint exists in that position.
We provides reference implementation of two TensorFlow Lite pose estimation models:
- MoveNet: the state-of-the-art pose estimation model available in two flavors: Lighting and Thunder. See a comparison between these two in the section below.
- PoseNet: the previous generation pose estimation model released in 2017.
The various body joints detected by the pose estimation model are tabulated below:
An example output is shown below:
MoveNet is available in two flavors:
- MoveNet.Lightning is smaller, faster but less accurate than the Thunder version. It can run in realtime on modern smartphones.
- MoveNet.Thunder is the more accurate version but also larger and slower than Lightning. It is useful for the use cases that require higher accuracy.
MoveNet outperforms PoseNet on a variety of datasets, especially in images with fitness action images. Therefore, we recommend using MoveNet over PoseNet.
Performance benchmark numbers are generated with the tool described here. Accuracy (mAP) numbers are measured on a subset of the COCO dataset in which we filter and crop each image to contain only one person .
|Model||Size (MB)||mAP||Latency (ms)|
|Pixel 5 - CPU 4 threads||Pixel 5 - GPU||Raspberry Pi 4 - CPU 4 threads|
|MoveNet.Thunder (FP16 quantized)||12.6MB||72.0||155ms||45ms||594ms|
|MoveNet.Thunder (INT8 quantized)||7.1MB||68.9||100ms||52ms||251ms|
|MoveNet.Lightning (FP16 quantized)||4.8MB||63.0||60ms||25ms||186ms|
|MoveNet.Lightning (INT8 quantized)||2.9MB||57.4||52ms||28ms||95ms|
|PoseNet(MobileNetV1 backbone, FP32)||13.3MB||45.6||80ms||40ms||338ms|
Further reading and resources
- Check out this blog post to learn more about pose estimation using MoveNet and TensorFlow Lite.
- Check out this blog post to learn more about pose estimation on the web.
- Check out this tutorial to learn about running MoveNet on Python using a model from TensorFlow Hub.
- Coral/EdgeTPU can make pose estimation run much faster on edge devices. See EdgeTPU-optimized models for more details.
- Read the PoseNet paper here
Also, check out these use cases of pose estimation.