The result of InSAR expresses the ground deformation in the change of colors. The gentle deformation of the ground causes the gentle change of color, the steep deformation of the ground does the steep change of color.
«Color bars«
When observing from ascending orbit
When observing from descending orbit
SAR satellite observes obliquely downward not directly below. It is in ascending orbit (northward) that the satellite observes from west and it is in descending orbit (southward) that the satellite observes from east. When the ground moves westward, if satellite observes in ascending orbit (northward), the ground moves near to the satellite. By contrast, if satellite observes in descending orbit (southward), the ground moves far from the satellite.
The numbers written under the color bars indicate the change in distance between the satellite and the ground in the satellite's line of sight. Negative values show the reduction of the distance between a satellite and the ground. This means the ground is lifted up, or moves westward if satellite observes in ascending orbit (northward), or moves eastward if satellite observes in descending orbit (southward).
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Based on blue, in the area where the color turns from blue to red, the ground moves far from the satellite. (ascending orbit : subsidence/eastward, descending orbit : subsidence/westward) In the area where the color turns from blue to yellow, the ground moves near to the satellite. (ascending orbit : uplift/westward, descending orbit : uplift/eastward) |
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The difference in displacement between the places in the same color is one of the integral multiples of the half SAR wavelength (11.8cm). This means the displacement changes just 11.8cm if the color turns back to the same color. |
