Multispectral Camera Simon Belkin, Audrey Finken, Grant George, & Matthew Walczak Final Project Review Team Parente

Problem & Solution Problem - Scientists desire the ability to capture measurements based on reflected energy (radiance) Common camera technology only captures light in three primary wavelengths: Red, Green, and Blue (RGB) in the visible spectrum  Solution – Multispectral camera captures wavelengths throughout the entire spectrum (including near- infrared/infrared)

System Design

Final Design Review Deliverables  Filter wheel turning and stopping at each filter for period of time, capturing image, and rotating to the next filter  Aberration mitigation for all filters  Transmitting captured image data from camera to Raspberry Pi  Identifying geological markers present in rocks and soil

Filter Wheel Mechanics

 FDR Solution  Program the filter wheel location in Python  Replace Hall Effect Sensor and add to Python program to identify start location  Accomplished  A program turns the filter wheel.  Hall Effect sensor used to recognizes start point location.  With the start point location the program can turn to specific filter and run through the filters pausing for outside response.

Filter Selection Selected 436nm 670nm 750nm 860nm 990nm Other 425nm 450nm 510nm

Optical System

 Out of focus condition due to the addition of filter wheel required compensation.  3.75” (95.3mm) of extension tubing.  A +33mm convex relay lens.  Thin lens equation, 1/d i = 1/f – 1/d o, determines the distance to the object, d o, and to the image, d i.

Required Focal Length Adjustment  Cameras are calibrated to focus on the visible portion of the light spectrum. As you travel further away from the visible spectrum and into the infrared spectrum, a slight shift in focus is necessary for camera to obtain sharpness of image. Filter Position at Light Path Current Arrangement of Filter Wavelength (nm) Dimension Needed for Focus Correction (mm) 1Blank NA will be 670nmNA Blank9.0

Adjusted Lens Position (between item #2 & #3)

Pi to Camera Interface

Problem – Driver Installation  Drivers provided, not officially “supported”  “Fedora 5” build conversion to Raspbian “wheezy”  Attempt to Cross-compile module  Module compiled, but unrecognizable by OS. Cannot start via terminal command  Pi integration determined to be low priority, efforts focused on ensuring quality image capture

Image Processing

Solution – Image Registration Problem - aberration  An optical aberration is a deviation from the optical predictions  Solution- Image registration  Image Registration is the process of estimating an optimal transformation between two images for all filters  Use of checkerboard test in Matlab to calibrate camera

Images Focused Through all Filters

Sift matching points on images  Points from image matching points from two images

Images after image registration

Questions