Hyperspectral Images from MTU Campus

(Note: these are preliminary data. They have not yet been flat fielded, dark current subtracted, destreaked or georectified.)

This is a new system; we are refining the processing.

The data presented below were acquired by FTHSI, or Fourier Transform Hyperspectral Imager. The site is the MTU campus, and the imagery is a single transect (swath) acquired in August, 1998. The pixel size is approximately 1 m.

The data have been processed to 32 bit floating point image format from the raw interferograms collected by the FTHSI. The data are unwarped, and have not been destreaked. Wil Slough performed the raw-to-image format processing.

MTU Data

RGB images of MTU campus
The images below are unwarped RGB images of the MTU campus. Wavelength combinations are indicated on each image. Pseudo-warped versions of images 2 and 3 were created by changing the aspect ratio from square to elongate along the flight direction.
These are preliminary data; data quality will improve substantially after flat fielding, dark current subtraction and destreaking.
1. RGB image of MTU (77 kb)
2a. RGB image of MTU (55 kb) 2b. Quick and dirty warp image (55 kb) 3a. RGB image of MTU (53 kb)
3b. Quick and dirty warp image (65 kb)

MTU campus grey scale images
Seven individual bands are displayed below, beginning at 431 nm, then at 100 nm increments beginning at 500 nm. Each image has been histogram equalized. Note how the SNR and streaking characteristics vary with wavelength.
Composite comparison of 7 wavelengths (138 kb)
431 nm (87 kb) 500 nm (85 kb)
600 nm (58 kb) 703 nm (52 kb)
802 nm (52 kb)
802 nm quick look warp image (45 kb)
900 nm (76 kb) 1006 nm (86 kb)

FFT attempt to reduce streaking
The data exhibit vertical streaking; they hyperspectral lab people are tracking down the source. Here I tried a simple FFT filter to reduce streaking. The result are shown below. There appears to be a difference between the raw and FFT-filtered images, but there is no dramatic improvement in the image quality. The streaking may not be sufficiently periodic to be reduced by the FFT.
Comparison of raw and fft image; attempt to remove streaks (178 kb)