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Remotely Sensed Imagery and Color Composites
4. Examine the airfield and its surroundings.
Question 10.8 Why do the areas in between the runways appear red?
5. Open a new image, this time with a 3-4-2 combination. Examine Burke
Lakefront Airport in this new image and compare it to the one you’ve
been working with.
Question 10.9 Why do the areas in between the runways now appear
bright green?
6. Open another new image, this time with a 3-2-4 combination. Examine
Burke Lakefront Airport in this new image and compare it to the others
you’ve been working with.
Question 10.10 Why do the areas in between the runways now appear
blue?
7. At this point, only keep the 4-3-2 image open and close the other two.
10.3 Examining Specific Brightness Values and
Spectral Profiles
Regardless of how the pixels are displayed in the image, each pixel in each
band of the image has a specific brightness value set in the 0–255 range. By
examining those pixel values for each band, you can chart a basic ‘spectral
profile’ of some features in the image.
1. Zoom in to the area around Cleveland’s waterfront and identify the
urban areas (in the image these will mostly be the white or cyan
regions).
2. From the Window pull-down menu, select New Selection Graph. Another
(empty) window (called Selection Graph) will open in MultiSpec.
3. In the image, locate a pixel that’s a good example of an urban or
developed area. The cursor will change to a cross shape, so give the pixel
one more click.
Important note: Zoom in so that you are only selecting one pixel with the
cursor.
4. A chart will appear in the Selection Graph window that will
graphically show the BVs for each band at that particular pixel
(see the first page of this lab for the portions of the electromagnetic
spectrum that match up with each band). The band numbers are on
the x-axis and the BVs are on the y-axis. The chart can be expanded
or maximized as necessary to be better able to examine the values.
Remotely Sensed Imagery and Color Composites
4. Examine the airfield and its surroundings.
Question 10.8 Why do the areas in between the runways appear red?
5. Open a new image, this time with a 3-4-2 combination. Examine Burke
Lakefront Airport in this new image and compare it to the one you’ve
been working with.
Question 10.9 Why do the areas in between the runways now appear
bright green?
6. Open another new image, this time with a 3-2-4 combination. Examine
Burke Lakefront Airport in this new image and compare it to the others
you’ve been working with.
Question 10.10 Why do the areas in between the runways now appear
blue?
7. At this point, only keep the 4-3-2 image open and close the other two.
10.3 Examining Specific Brightness Values and
Spectral Profiles
Regardless of how the pixels are displayed in the image, each pixel in each
band of the image has a specific brightness value set in the 0–255 range. By
examining those pixel values for each band, you can chart a basic ‘spectral
profile’ of some features in the image.
1. Zoom in to the area around Cleveland’s waterfront and identify the
urban areas (in the image these will mostly be the white or cyan
regions).
2. From the Window pull-down menu, select New Selection Graph. Another
(empty) window (called Selection Graph) will open in MultiSpec.
3. In the image, locate a pixel that’s a good example of an urban or
developed area. The cursor will change to a cross shape, so give the pixel
one more click.
Important note: Zoom in so that you are only selecting one pixel with the
cursor.
4. A chart will appear in the Selection Graph window that will
graphically show the BVs for each band at that particular pixel
(see the first page of this lab for the portions of the electromagnetic
spectrum that match up with each band). The band numbers are on
the x-axis and the BVs are on the y-axis. The chart can be expanded
or maximized as necessary to be better able to examine the values.