Purpose

This panel is used to create a shapefile of polygons to sample a raster image with a given resolution; the shapefile is introduced as input in the Image Subsampling panel to create the InSAR dataset.

An example involving this panel can be found in the tutorial.

Technical Note

This is a simple interface to load a raster image (typically, a “_disp” file from SARscape interferometric processing) as background to define the polygonal areas where points will be picked to generate an InSAR dataset for modeling. For every polygon, a resolution (in meters) defining the distance between points must be defined. The user does not have to care about overlapping polygons: during the image sampling (through the Image Subampling panel) the highest sampling rate, i.e. the finer resolution, will be used in overlapping areas.

Creating/Editing a polygon: use the left mouse button to draw the polygon. One click to start drawing and add a new vertex; double click to close the polygon. During editing, use the right mouse button, single click, to delete the last vertex. After a polygon is closed, a further editing is not possible.

Delete polygons: click the mouse wheel in the map and the keyboard delete button, or select the polygon(s) in the table and press the “Delete polygon” button.

Zoom/Pan the image: zoom in/out the map scrolling the mouse wheel; click the wheel and move the mouse to pan the image.

The min/max values for the stretching interval can be used to highlight deforming zones of the image.

Input Parameters

Select raster image…

Use the button to load the raster displacement image ('*_disp' file from SARscape processing is expected). It can have Lat/Lon or UTM coordinates; the same coordinate system will be applied to the output shapefile of polygons.

Stretching interval

Define the minimum and maximum values to draw the image. Blue-to-red palette is linearly stretched between these two values

Sampling areas table

Set, for every polygon, the resolution (in meters) used to sample points, before saving them to the shapefile. Don’t change the polygon name.

Note: It is important to set a resolution that generates a fair number of samples. The suggested number of samples is around 20,000–30,000. This ensures

Output Files

Output shapefile

Shapefile of polygons to be used with the Image Subsampling panel.

General Functions

The window will be closed.

Help

Specific help document section.

Specific Function(s)

None.

References

None.

Interferometry - Displacement Modeling - Sampling Areas

Interferometry - Displacement Modeling - Sampling Areas

Purpose