I work on smoe earthquake in Japan and I want to calculate vertical and horizontal displacement, I have read on this forum how to convert LOS to vertical dispalcement with this formula (unw_phase5.6)/(-4pi*(cos(rad(incd_angl))), than I from my LOS(Phae to displacement) deduct my calculateted vertical displacement to get horizontal dispalcement. I want first to check with you is this good way or I am tottaly wrong, and I want to ask you secound question I have ascending and descending how can I combine them to get horizontal and vertical dispalcement?
S1 is good in detecting displacements in E-W direction, but it is better to have some in-situ data for the single event as earthquakes. I wouldn’t be confident on horizontal displacements you get from the formula you provided.
vertical displacements have been heavily discussed in some topics (mostly here). My personal conclusion is that there is no standard way of doing it. There are many approaches, most of them require computing which cannot be done entirely in SNAP (e.g. vector or matrix based calculations).
These publications give nice summaries on the topic:
- Wright et al. (2004): Toward mapping surface deformation in three dimensions using InSAR
- Hu et al. (2014): Resolving three-dimensional surface displacements from InSAR measurements - a review
- Foumelis et al. (2016): Vector-based approach for combining ascending and descending persistent scatterers interferometric point measurements
ABraun and hriston_bg thank you very much on this advices that you give me I am going to try some of other methods to see if I will get same results like my.
hello, please I want to check if I compensate for the displacement( d LOS ) with its sign (that resulted with me from SNAP)in this relation
thank you in advance
Hi, I have a follow up query as you said that S1 is good in detecting displacements in E-W direction, from where can I get to study more about the sensor’s sensitivity in N-S and E-W direction ?
It is not related to ‘sensor sensitivity,’ but rather to orbit geometry. When we have a small north-south projection component, we experience lower accuracy in the north-south projection. See this interactive InSAR example on Google Colab to compare projection components: Google Colab