4 Using the outputs
In WP 2 ground deformation SAR images from different sensors are used: X-band TerraSAR-X data (1-3m resolution) (http://www.terrasar.de/terrasar-x.html), C-band ERS/ENVISAT (30m) and L-Band ALOS/PALSAR data (5 ~ 15m). Following products are uploaded into the VFRS system and database: interferogram, differential interferogram, SAR intensity image, deformation map, coherence map and PSI velocity map with its coherence and topography correction. You can find the description of each product on its ”meta data”. For more details please take a look at following example.
4.1 Data Interpretation: example interferogram
Add the layer of ‘InSAR Imagery’, you can find your detail information on your left side under meta data:
a. Select one of products in this category, e.g. ‘Interferogram’, see Fig. 7
b. Set filter
i). Select data point: select one of specific satellite, format ‘Satellite Acquisition Mode’ e.g. ‘TerraSAR-X Stripmap’
ii). Date: select specific date you need, format ‘date1 – date2’, e.g. ‘2009-03-28 – 2009-04-08’ that the SAR image from 2009.03.28 as master and 2009.04.08 as slave are used for generation the products.
- Fig 7. Select the layer of ‘InSAR Imagery’-‘Interferogram’
c. Load image and use ‘zoom to image’ function to center the image, see Fig. 8
d. Auxiliary Information: information data and legend bar, see Fig. 8
e. Get the pixel information: click the with mouse on selected pixel
- Fig. 8 ‘Interferogram’ with info data and legend bar
4.2 Combined interpretation: semi-transparent
The combined interpretation of interferogram with coherence image is helpful for correct interpretation, because the signal the pixel of low coherence presents less importance as with high coherence. By setting to semi transparent you could overlay two images which are loaded before together, see Fig 9.
- Fig 9. combined interpretation of interferogram with cohnerence image as background
4.2 Metadata structure
The interferogram and differential interferogram products are all in GEO-TIFF format. The PS products are in KML format. You can download all the products from our database. The metadata structure is formatted with XML data, one example is given in following text.
-<InSAR project_id="ExuperyV1.0" volcano_id="0101-04=">
+ <range_upperleft>
+ <range_lowerright>
+ <start_datetime>
+ <end_datetime>
+ <files> // adding the products, i.e. interferogram image and the ASCII data
<file id="dphase_image" format="GeoTIFF" filesize="170808">
<original_path>ftp://…/GTC_DPHASE_if_20080124_20080204.tif</original_path>
<local_path>/InSAR/GTC_DPHASE_if_20080124_20080204.tif</local_path>
</file>
<file id="dphase_data" format="ASCII" filesize="2214036">
<original_path>ftp://…/GTC_DPHASE_if_20080129_20080209.dat</original_path>
<local_path>/InSAR/GTC_DPHASE_if_20080129_20080209.dat</local_path>
</file>
</files>
+ <author>Xiaoying Cong, TUM</author>
+ <software>DLR GENESIS, Nico Adam</software>
+ <external_DEM>SRTM DEM</external_DEM>
+ <minimal_displacement>-0.027597</minimal_displacement>
+ <maximal_displacement>0.024774</maximal_displacement>
+ <effective_baseline>-3.75E+01</effective_baseline>
+ <height_ambiguity> -2.018E+02</height_ambiguity>
+ <original_azimuth_resolution_per_pixel>4.3E-01</original_azimuth_resolution_per_pixel>
+ <looks_of_azimuth>15</looks_of_azimuth>
+ <original_range_resolution_per_pixel>4.3E-01</original_range_resolution_per_pixel>
+ <looks_of_range>15</looks_of_range>
</InSAR>
Within the <range_upperleft> and <range_upperleft> tags the coordinates (longitude and latitude) of the corners with their uncertanties are written. Similar case is for <start_datetime> and <end_datetime> tags.
<files> and <file> tags are used to added results. <file> is formatted with “id” for product name, “format” for product format.
For each product set additional information is given, like: <software> - processing software; <external_DEM>; <minimal_displacement> and <maximal_displacement>; <effective_baseline>; <height_ambiguity> ; <original_azimuth_resolution_per_pixel> * <looks_of_azimuth> = the pixel resolution in azimuth [m]; <original_range_resolution_per_pixel> * <looks_of_range>= the pixel resolution in range [m]