After that quick look at the scene setting, we are set to start our exercise in image interpretation. As this could be your first effort at this process, we suggest you now become familiar with this Landsat subscene as we rendered in all seven TM bands.
|TM 1||TM 2|
|TM 3||TM 4|
|TM 5||TM 6|
Note that TM Band 6 appears blurred or fuzzy. This is the thermal band which has a spatial resolution of 120 m compared with the 30 m of the other bands.
Each image has its own tonal characteristics, along with distinctive shapes defined by tonal boundaries and patterns, that help to identify ground features. You can view the histograms for each band clicking on each of the following links: histogram 1, histogram 2, histogram 3, histogram 4, histogram 5, histogram 6, histogram 7. Note that each histogram is bimodal, having one peak at very low values (water) and the second at various mid-DN values.
Feature Identification Map
In the treatise that follows, to focus attention, we identify specific features and patterns by letters on an overlay of the background image in which we flattened the gray tones. Take a look at the map now. You can link to this map any time by clicking on the underlined and colored letter. (To remove it once displayed, click the X button at the upper right corner of the screen.) To make a convenient reference, we suggest you print this map and keep it handy if you do not wish to download the map each time it is referred to on later pages. The background image is made from TM 1 in which the gray levels were deliberately contracted to show only small contrasts.