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MobileDataCaptureKit

MobileDataCaptureKit is a lightweight, modular Android application designed for researchers to capture synchronized camera and sensor data using a smartphone.

This tool integrates the Android Camera2 API with multiple onboard IMU sensors to record high-quality video and time-aligned sensor streams. It is optimized for research in mobile sensing, computer vision (SLAM/VIO), robotics, and dataset collection.

User Interface

app_interface

The application interface is designed for simplicity and real-time monitoring:

  1. Real-Time Sensor Overlay (Top-Left):
    • Displays instantaneous readings for ACC (Accelerometer), GYRO (Gyroscope), PRESS (Barometer), and MAG (Magnetometer) to ensure sensors are active before recording.
  2. START DATA (Blue Button):
    • Starts logging raw sensor data to a CSV file without recording video. Useful for IMU calibration or non-visual data collection.
  3. Shutter Button (Center Camera Icon):
    • Captures a high-resolution still image and saves it to the system Gallery.
  4. START VIDEO (Red Button):
    • Begins video recording. This triggers the logging of frame-level metadata.

Settings Interface

settings_interface

Camera Settings

  • Target FPS: Select between 15, 30, or 60 FPS.
    • ⚠️ Note on 60 FPS: To achieve a stable 60 FPS, the Exposure Time must be set lower than 8ms (< 8,000,000 ns) in Manual Exposure mode. If the exposure is too long (e.g., default 15ms), hardware readout latency limits the camera's maximum frame rate to below 60 FPS..
  • Focus Mode: Toggle between Continuous Auto Focus and Manual Focus (Locked at 0.0f/Infinity). Manual focus is recommended for SLAM to prevent focal length changes.
  • Exposure Mode: Toggle between Auto and Manual.
  • Manual Parameters:
    • Exposure Time (ns): Set absolute exposure duration in nanoseconds (e.g., 10000000 for 10ms). Short exposure reduces motion blur.
    • ISO Sensitivity: Manually set ISO (e.g., 800) to balance brightness when using short exposure times.

Sensor Frequencies

  • Adjustable Sensors: Set sampling rates (Fastest, Game, UI, Normal) for Accelerometer, Magnetometer, and Barometer.
  • Gyroscope (Fixed): The Gyroscope frequency is locked to FASTEST (~200Hz+).
    • Reason: When the Camera is active, the Android hardware abstraction layer (HAL) reserves high-frequency gyro data for OIS/EIS stabilization, overriding application-level frequency requests.

Authors

黄俊植（Junzhi Huang） – Shanghai Jiao Tong University — （Email: biscu0@sjtu.edu.cn）

王士壮（Shizhuang Wang） – Shanghai Jiao Tong University — （Email: sz.wang@sjtu.edu.cn）

Features

  • Advanced Camera2 API Integration

    • Records video (H.264/MP4) with configurable parameters.
    • Captures high-resolution still images.
    • Frame-Level Metadata: Logs Timestamp, Exposure Time, ISO, and Focal Length for every video frame to a CSV file.

  • Multi-Sensor Data Logging

    • Synchronously records data from:
      • Accelerometer
      • Gyroscope
      • Magnetometer
      • Pressure Sensor (Barometer)
    • Data is saved in CSV format with high-precision timestamps.

  • Modern Android Storage Support

    • Fully compatible with Android 10+ Scoped Storage.

    • Videos and Images are automatically saved to the system Gallery.

    • Raw sensor data files are accessible via the app's private external storage

      (/Android/data/...).

  • Modular Architecture

    • Refactored codebase separating Camera, Sensor, and File logic for easy extension and maintenance.

Project Structure

/app
├── java/com/example/mobiledatacapturekit
|	├── Appconfig			   # Parameter Settings
│   ├── MainActivity.java      # UI Controller & Permission handling
│   ├── CameraHelper.java      # Camera2 API & MediaRecorder logic
│   ├── SensorHelper.java      # SensorManager & IMU data processing
|	├── SettingsActivity.java  # Read Settings
│   └── FileUtils.java         # File I/O & MediaStore integration
│
├── AndroidManifest.xml        # Permissions & Hardware feature declarations
└── res/layout
    └── activity_camera.xml    # User Interface layout

Data Output Format

The application generates the following files during recording:

1. Video Metadata (META_yyyymmdd_HHmmss.csv)

Logs camera properties for each frame synchronized with the video.

Frame,Timestamp,Exposure,ISO,FocalLen
0,1769523611631,18613238,711,6.81
1,1769523611702,18613238,711,6.81
2,1769523611740,18613238,711,6.81
3,1769523611772,18427724,711,6.81
4,1769523611801,18233376,711,6.81
5,1769523611835,17897684,711,6.81
...

2. Sensor Data (SENS_yyyymmdd_HHmmss.csv)

Logs high-frequency IMU data.

Timestamp,SensorType,X,Y,Z,Value
22:20:10.385,GYRO,-0.5715,0.3893,0.1707,
22:20:10.386,ACC,0.4098,9.4433,3.2877,
22:20:10.387,GYRO,-0.5751,0.3746,0.1671,
22:20:10.388,ACC,0.4289,9.4433,3.3308,
22:20:10.389,GYRO,-0.5715,0.3600,0.1622,
22:20:10.390,ACC,0.4289,9.4337,3.3733,
22:20:10.391,MAG,-12.2000,-43.4076,5.4534,
22:20:10.392,GYRO,-0.5678,0.3392,0.1535,
22:20:10.393,ACC,0.4624,9.4289,3.3972,
22:20:10.394,GYRO,-0.5556,0.3244,0.1472,
22:20:10.394,ACC,0.4433,9.3858,3.4588,
22:20:10.396,GYRO,-0.5444,0.3073,0.1374,
22:20:10.401,ACC,0.4624,9.3326,3.5061,
22:20:10.407,PRESS,,,941.8298
...

Videos/images are automatically saved to the system gallery, and can also be found at

(Android/data/com.example.mobiledatacapturekit/files/Videos...).

Original CSV data is securely stored in the app's private directory

(Android/data/com.example.mobiledatacapturekit/files/SensorData...).

Frame-level data recording: When recording videos, a synchronized Metadata CSV file is automatically generated to record the exact timestamp, exposure time, ISO, and focal length of each frame. It is stored in the app's private directory (Android/data/com.example.mobiledatacapturekit/files/MetaData...).

Note：You can use DataSeparation.py to quickly separate the sensor data into four files: ACC.csv, GYRO.csv, MAG.csv, PRESS.csv. The files are as follows

ACC.csv

Timestamp,X,Y,Z
22:20:10.386,0.4098,9.4433,3.2877
22:20:10.388,0.4289,9.4433,3.3308
22:20:10.390,0.4289,9.4337,3.3733
22:20:10.393,0.4624,9.4289,3.3972
22:20:10.394,0.4433,9.3858,3.4588
22:20:10.401,0.4624,9.3326,3.5061

GYRO.csv

Timestamp,X,Y,Z
22:20:10.385,-0.5715,0.3893,0.1707
22:20:10.387,-0.5751,0.3746,0.1671
22:20:10.389,-0.5715,0.3600,0.1622
22:20:10.392,-0.5678,0.3392,0.1535
22:20:10.394,-0.5556,0.3244,0.1472
22:20:10.396,-0.5444,0.3073,0.1374

MAG.csv

Timestamp,X,Y,Z
22:20:10.391,-12.2000,-43.4076,5.4534
22:20:10.416,-13.2980,-43.3100,5.4778
22:20:10.426,-11.1508,-43.9200,7.8934
22:20:10.435,-12.9686,-44.5178,4.2090
22:20:10.441,-14.4936,-43.8590,4.7702
22:20:10.448,-17.7754,-45.6890,1.5372

PRESS.csv

Timestamp,Value
22:20:10.407,941.8298
22:20:10.429,941.7969
22:20:10.447,941.8349
22:20:10.458,941.8148
22:20:10.482,941.7961
22:20:10.496,941.8292

Requirements

  • Android Studio (Flamingo or later recommended)
  • Android SDK Platform 33 (Compile SDK)
  • Minimum Android Version: Android 10 (API Level 29)
  • Device: Smartphone with Camera2 API support and relevant sensors.

Getting Started

1. Clone the repository

git clone https://github.com/HuangJZh/MobileDataCaptureKit.git

2. Open in Android Studio

  • Select File > Open and choose the MobileDataCaptureKit directory.
  • Allow Gradle to sync and download dependencies.

3. Build & Run

  1. Connect an Android device via USB.
  2. Ensure "Developer Options" and "USB Debugging" are enabled on the phone.
  3. Click **Run * in Android Studio.

4. Permissions

Upon the first launch, grant the following permissions:

  • Camera (for video/photo)
  • Microphone (for audio recording)
  • Note: Storage permission is not required for Android 10+ due to Scoped Storage implementation.

License

This project is open-source and available for research and educational purposes.

About

A lightweight Android tool for researchers to capture synchronized camera and sensor data using smartphones. Supports Camera2 API, accelerometer, gyroscope, magnetometer, pressure sensor, and more — ideal for mobile sensing, computer vision, robotics, and data collection experiments.

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