In the INSAR product, it includes the optional _lv_phi.tif.xml file. In this file, the data range of the lv_phi is described as -PI/2 to PI/2.
Correction
The correct lv_phi data range should be -PI to PI. Following is the explanation.
The look vector is defined as the vector from pixel to satellite. The lv_phi is the angle between the East direction and the horizontal projection of the vector. The angle increases counterclockwise from the East and decreases clockwise. If the horizontal projection of the vector points below the East direction, then it value is negative. The range of the lv_phi is -PI to PI. For Sentinel-1 satellite, if the satellite is ascending, the lv_phi is -PI to -PI/2, where PI is 3.14. If the satellite is descending, lv_phi is in the range of 0 to PI/2.
The bug
In the INSAR product, it includes the optional _lv_phi.tif.xml file. In this file, the data range of the lv_phi is described as -PI/2 to PI/2.
Correction
The correct lv_phi data range should be -PI to PI. Following is the explanation. The look vector is defined as the vector from pixel to satellite. The lv_phi is the angle between the East direction and the horizontal projection of the vector. The angle increases counterclockwise from the East and decreases clockwise. If the horizontal projection of the vector points below the East direction, then it value is negative. The range of the lv_phi is -PI to PI. For Sentinel-1 satellite, if the satellite is ascending, the lv_phi is -PI to -PI/2, where PI is 3.14. If the satellite is descending, lv_phi is in the range of 0 to PI/2.