i am getting the time series plot… but i dono how to infer it… is it taking the mean displacement of all MP’s? @thho
Then another query is that, in TS comparison, how am i supposed to specify the time series… I dont have a clear idea about it…
Moreover, could anybody send your publications or the manuals in which i can find the inference of the results obtained from PS technique…? (if possible kindly mail to : firstname.lastname@example.org)
Would you please to find below the link of my PhD thesis, you could find out, how to handle with each single Scattered point,
Also this article,
thankyou lots @falahfakhri
thank you this is really helpful @Gijs how can i get the incidence angle value? and what if i only have descending data? can i still convert the LOS displacement to vertical displacement?
you can get the incidence angle by computing radiometric correction in snap on your splitted (and orbitted) product, in the metadata file a max/min value is shown and you can choose a value in between this dependent on where your AOI is.
you do not need ascending and descending data to compute the vertical displacement but keep in mind using only 1 flight direction can introduce errors related to just that flight direction and may distort some patterns. I have not yet found an article on this but maybe @thho , @mdelgado , @falahfakhri or @ABraun can tell you more about this.
This issue is already discussed in here,
The displacement is in LOS, but it is possible to get the vertical displacement, it is well explained in this post,
Source of the post
And in this post as well,
Source of the post
More details is explained in here,
It’s also explained here how to convert LOS to Vertical dis. (Source of the post)
I didn’t find the literature, but I asked our colleague @johngan about it
I would like to say a pair of things to consider:
- with only one orbit, you may be neglecting or losing information, obtaining only partly the vertical signal, this could be ok if both ascending and descending says that you have the same phenomena (subsidence or uplift).
- If ascending and descending orbit show different phenomena, the result decomposition shows predominance on horizontal movement, and could reach even that vertical deformation is not happening. This always depending from case to case.
- if ascending and descending show both subsidence, surely the final vertical movement will be subsidence, but you can not assume this before getting both results.
I strongly recommend to get both ascending and descending results before publishing any partial projection of asc and desc, instead to get the real one, only possible with both geometries, as you may publishing not real results.
Results of horizontal and vertical decomposition are several ones, so please just search in literature (from PSI results https://www.mdpi.com/2072-4292/11/2/129/pdf) but as this is mine, please search other sources as well to convince yourself.
It is better to show LOS results, that uncomplete vertical ones… this is my opinion
I do indeed use both ascending and descending orbit because of the reasons you mention that is widely discussed on this forum.
My AOI is only prone to vertical displacement since i am investigating subsidence due to permafrost, this is why i use the ‘‘simpler’’ formula that just uses the incidence angle and assumes only vertical displacement.
I have read multiple papers on the topic of combining ascending and descending data including yours to obtain the 3D displacement but i must say the process dazzles me! Unfortunately no scripts are available for computing this and due to time limits i am probably not able to construct these myself. Although i am a perfectionist, for my 3 month during bachelor thesis more is sadly not possible since i have to analyze the data and write a paper as well.
Most people looking for the vertical displacement, including @dianalalitya for whom i asked the question are just looking for the simple formula although this is indeed not perfect.
Your statement about showing LOS displacements is indeed correct, especially if you only relate the displacements generated with each other and have no ground truth comparison.
I agree with you.
I wanted just to be sure you know the assumptions you are taking and that these kind of assumptions you can only do if you have further information, and knowing that you will be neglecting other signal.
Once you are aware of that, you can go.
Good luck with your Bachelor thesis.
This is the result i obtained using Visualizer… May i know what this time series graph indicates… Is it the mean displacement?
I believe is actually the time series deformation in mm for the selected point with respect to the reference point.
but i dint specify any selected point… i am quite confused…
the visualizer starts by displaying the first point…which point that is, is pretty random, depending on your data set. just click on a point in the map to get tet info of this point. There is no option for mean time series yet. So @mdelgado is right.
okay @thho… will try as you said…
Thank you @mdelgado
And i tried and getting the same…
But how to save it… and how to use TS comparison?
A few thoughts about your output:
- your point density is very very high…you should increase the weeding parameter in StaMPS
- it looks like that there is a ramp in your data, have you apllied the deramping? If you do not know what I mean with that, have a look at the StaMPS manual, and read about all options during steps 5-6 and considre using them
- and btw, nice to see that you have managed the processing, now you can play with the parameters of StaMPS and by time you will get a good feeling for them and what they do…I suggest using the Visualizer massively to check about what happens to your data after changing parameters…I learnd a lot this way and it was the motivation for the app in the first place. Good luck!
sure… @thho… Just because of the help i obtained from this forum i have come this far…
Will check the stamps manual and try modifying the parameters…
Will let you know the results i obtain after modification…
Thank you so much…
save what? the time series? There is no direct way to save the plot…I can work on that if it is useful. The TS comparison is a bit messy to use and I do not like it a lot…I even thought about excluding it again…but still if you want to use it, every time you select a point in the map, beneath the plot there is the info of the number of the point. You can use the single PS viewer to look up some interesting points, note done the numbers, change to ts comparison and select the numbers from the dropdown…which I do not like but have not changed it yet. After that you are able to see multiple time series in one plot.
oh… thats cool…
My Rstudio get hanged at times as i have numerous point is guess… So it takes ample time to do each step… Will follow your suggestion by increase the weeding and work with less number of points in order to get good interaction with the visualizer…
Will get to you after reducing the points…
By the way, thanks for the visualizer tool… @thho
You are welcome!
Decreasing the amount of points is a good idea…the rendering with the visualizer is pretty expensive concerning computation…if you are happy with the PS density, but you still have a lot of points, you have to work with spatial subsets and display the points after an other…but for me, weeding was fine all the time
Even i find more number of points and it confuses me on focusing with the essential MP’s… I thought of subset too and i did try it, even so the density of points are very high and i get numerous ones… I think i should opt weeding…
However, While running stamps in matlab i so far just used stamps(1,1) then stamps(2,2)… likewise command to run each step, and i dint know that there is an option to change the parameters… Where should i change the parameter? I went through the manual and it has a detailed explanation on the utilization of each parameter. But i am not sure where to modify those…
"You can modify any parameters from the default using
setparm(‘param name’,param value)"
i found this in the manual, should i use this prior to the stamps(5,5) or likewise?
And @thho, i would like to read your publications or thesis if any (if available), so that i could do better in inferring the results i have obtained… Kindly send me if possible (email@example.com)