IMAGE PREPARATION        

layers.JPG (25621 bytes)The raw data for this project was a set of Landsat 5 Thematic Mapper (TM) images that were collected during 1992.  The images were provided in their native band sequential (.bsq) format and had an associated header file (.dda).  The bsq files contained the images while the dda files contained all relevant information for viewing and registering the images.  The individual layers chosen for this project had to be 'stacked' on top of one another.   The images seen to the left are the three raw images.  The red layer is TM band 4, it has a ground resolution of 30 meters and a spectral range of .75 to .90 microns.  The green layer is TM band 5, it also has a ground resolution of 30 meters and has a spectral range of 1.55 to 1.75 microns.  The final and blue layer is TM band 3, it has a 30 meter ground resolution as well and has a spectral range of .63 to .690 microns.   Bands 3, 4 and 5 represent the visible, near infrared, and short wave infrared wavelengths respectively (ref. 4).  The task of 'stacking' the images was completed within an imaging software package called PCI imageworks.  The resultant layering (below) was then exported to Erdas Imagine for the balance of the processing.           

 

 

                Orig.jpg (24656 bytes)

 


 

The final procedure to prepare the image for analysis was to register the image to its coordinate space.  The information to perform the operation was found in the image header file.  This process was performed with Erdas's Imagine 8.3.  To complete this task, ground control points (gcp's) were selected at the four corners of the image.  The control points were then matched to the appropriate ground control coordinates (gcc's).  In this case, the contol values were in the Universal Transverse Mercator (UTM) zone 17 north projection and contained the measuring units of meters.  The resulting resampling registered the 'raw' image to the UTM coordinate space for further analysis.  The first projected image of the northeast portion of lower Michigan can be seen below.

 

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