<title>Automated coregistration of MTI spectral bands</title>

Abstract

In the focal plane of a pushbroom imager, a linear array of pixels is scanned across the scene, building up the image one row at a time. For the Multispectral Thermal Imager (MTI), each of fifteen different spectral bands has its own linear array. These arrays are pushed across the scene together, but since each band's array is at a different position on the focal plane, a separate image is produced for each band.The standard MTI data products (LEVEL1B R COREG and LEVEL1B R GEO) resample these separate images to a common grid and produce coregistered multispectral image cubes. The coregistration software employs a direct "dead reckoning" approach. Every pixel in the calibrated image is mapped to an absolute position on the surface of the earth, and these are resampled to produce an undistorted coregistered image of the scene. To do this requires extensive information regarding the satellite position and pointing as a function of time, the precise configuration of the focal plane, and the distortion due to the optics. These must be combined with knowledge about the position and altitude of the target on the rotating ellipsoidal earth.We will discuss the direct approach to MTI coregistration, as well as more recent attempts to "tweak" the precision of the band-to-band registration using correlations in the imagery itself.

Pre-processing considerations of IRS-P6 LISS-4 imagery

“…Pope et al (2004) has explained the LANL (Los Angels National Laboratory) experiences with Coregistration of MTI images. Theiler et al (2002) has also done a study for estimating the effect of various errors for MTI spectral bands. The perfect alignment of odd and even arrays requires accurate sensor model connecting the satellite orbit, attitude and the target location.…”

Automated co-registration of images from multiple bands of Liss-4 camera

“…Co-registration using the imaging geometry and auxiliary data is achieved indirectly by registering each band to a common coordinate system on the ground. Theiler et al (2002), explain automated co-registration of Multi-spectral Thermal Imager (MTI) bands using photogrammetric methods. They have also reported the automated image registration of MTI imagery through entirely image-based methods.…”

“…Some errors like velocity and attitude have larger effects than others, and it is important to quantify these effects. Following the method of estimating the effect of various errors in registration of MTI bands proposed by Theiler et al (2002), we compute the magnitude of these effects for the L4 sensor.…”

Resolution Enhancement of Multilook Imagery

“…If the images are co-registered to each other, and also are aligned to absolute latitude and longitude coordinates, they are said to be geo-registered. Multispectral sensors such as the MTI require co-registration of the images for each spectral band because each band image is formed by a separate line detector [51]. Image-to-image registration is often done using ground control points or cross-correlation [52].…”