A portable thermal camera with visual image fusion

Table of Contents

• Introduction
• Electronics
• Software
• Results
• Hardware mounting
• References
• Contact

Design records:

• Initial
• Real Time Clock Improvement

Introduction

This project details the software and hardware to build a portable camera which is capable of combining the images from a thermal camera and a normal camera. Project features:

• Multiple Image modes: Thermal Rainbow palette, Thermal Gray scale, Visual and Thermal image mix, etc.
• 2.8” Touch screen (ILI9341 and XPT2046). Temperature pointer at the touched location.
• Low power Off design. Power off with Real Time Clock (RTC) consumption as low as 7.5 uA.
• Navigation and shutter buttons.
• Battery voltage measurement
• Open source hardware and free tooling through out all the project.
  • Openmv H7 with Lepton 3.5 Thermal Camera (SPI master) and SD card.
  • Secondary Openmv H7 Plus with OV7725 sensor for Visual image (SPI slave).
  • Auxiliary controller with PIC16F886 (RTC, Buttons, Battery check)

Electronics

See: Design decisions involved in version 1

Design records:

• Initial
• Real Time Clock Improvement

Software

Main features:

• Save photos in bmp format
• Choose a preview mode:
  1. Thermal mode with Non-linear color
  2. Same as mode-1 with temperature blobs detection
  3. Thermal mode with Linear Grey (ideal for: Night vision. Playback analysys of pictures)
  4. Visual image. Image from the Openmv with visual camera
  5. Mix image. Interlaced images from mode-1 and mode-4
• Thermal options:
  • Manual trigger of the Flat Field Correction
  • Change Emissivity
  • Choose Gain mode
  • Set a static or dynamic temperature range:
    • Both methods will use radiometric measurements and deliver absolute temperature.
    • Static will saturate the image color at the desired minimum/maximum. Useful for identifying a specific temperature
    • Dynamic will adjust minimum and maximum of the image scene and get best overall contrast.
    • The chosen mode can be saved for next usages.
  • Touch the screen to get the temperature in a specific point
    • Setting to enable/disable cursor in full screen mode
• Playback photos
  • Navigate up and down through saved photos
  • Analysis of pixel temperatures (Valid for grey-scale thermal images)
  • Delete photos
• Utility features:
  • Set time and date
  • Save and restore settings
  • Calibrate touch coordinates
  • Calibrate Field of view of the visual image, to perfectly match the Thermal image for preview mode-5

For further indications on how to use and understand the software:

• Software description
• Software deployment

Hardware mounting

For Lepton 3.5 mounting, see: Mounting Lepton

Results

References

Openmv links:

• General info: https://openmv.io/
• Framework repo: https://github.com/openmv/openmv
• Micropython repo: https://github.com/micropython/micropython

Several datasheets or manufacturer documents have been cached in this project so future readers have the copy of the document that was used during the design of this project:

Reference values for ILI9341 in Application notes Datasheet PIC16F866 (including AC/DC characteristics) Lepton 3.5 Engineering datasheet Lepton 3.5 API

Reference repos while I was getting started with the touch display:

• To display on ILI9341: https://github.com/OutOfTheBots/OpenMV_TFT
• To read touch from XPT2046: https://github.com/Luca8991/XPT2046-Python

Linked in Jonatan Asensio Palao

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Tags: camara termica, lepton, openmv h7, pic16f886, boostc, eagle, crystal 32k, rtc, real time clock, ili 9341, xpt 2046, mt3608, tp4056