Spectral Unmixing Endmember File Error

snap
1

Hello,

I am trying to use the Spectral Unmixing feature in SNAP on a S3 subset. I have created a tab separated csv file using python in several different ways. The csv endmember file uploads successfully and the individual endmembers can be seen in the LSU popup window. However, when I click Run, I get error saying “Matrix is Singular”. I am not sure what this means or how to address the problem.

If I create a tab separated csv file with the same data using Excel the LSU tool runs successfully. I am not sure what difference using python is creating.

Thanks,
Jeremy

2

I think the format is correct in both cases. But are you sure that you use the same values in both cases?

A matrix is singular if its determinant is zero.

3

Hello @marpet .

I am also having problems with the Endmember file for the unmixing. I exported my endmembers from Envi in ASCII format and then converted it in a tab separated CSV file using Excel and Notepad. It looks like this:

image.png1349×202 12.1 KB

However, when I added it to SNAP I am not getting any error but it is not showing any endmember. Do you have any suggestion on how to solve this?

Thanks,
Isabel

4

The endmember file should follow the format which is described in the help.

image.png965×521 36.4 KB

Especially, the leading " is not correct in your file.

5

Thanks @marpet. How many Endmembers does the Unmixing allow? I am not able to add more than 10.

6

No, there is no artificial limit. If you like you can send me the endmembers files, e.g. as PM. Then I can test it.

8

All Endmembers are loaded into the tool

There is only a slider missing in the list of endmembers. If you further step down through the list by the cursor keys you see different spectra highlighted in the graph.

Also, it would be good if you have a different name for each of the endmember.
And you have to make sure that you have more source bands then endmembers.

9

ok, I see. Perfect. Thank you.

Yes, I do have different names and around 271 source bands.

thank you for your time!

10

Excuse me, how do you get these Endmembers?

11

Spectral Unmixing Tools

image
image1549×878 173 KB

12

I mean in the Endmembers section, How can we add this “Forest”, “Cropland” and … items?

13

Please read the help, it’s well explained,

image
image.png1564×764 195 KB

14

hi, I’m trying to use spectral unmixing tools in SNAP, I’ve already converted the endmembers file into the csv tab-separated file using excel and notepad, and it looks like this :

Screenshot 2024-04-22 092739
Screenshot 2024-04-22 092739985×145 46.7 KB

and when I added it to SNAP, I’m not getting any error but it is not showing any endmember. Do you have any suggestion how to solve this problem?

thanks,
maximum

15

Not sure if this causes the problem but I noticed that your endmembers have all the same name.

16

thanks, @Marco_EOM , I changed all the endmembers name and It actually worked, but then there was another problem when I tried to Run the product, and it showed like this :

Screenshot (2019)
Screenshot (2019)1366×768 106 KB

do you know how to solve this kind of problem??? thank you

17

The reason could be that you have moved source product from one location to another.
It is a BEAM-DIMAP product, right?
You might have moved only the *.dim file, but you also must move the *.data directory.

18

I double-checked the folder .dim and .data. They are located in the same folder. But when I tried to Run the product again, it gave me the same error… I’m really confused now

19

hi, @Marco_EOM I finally know what the problem is, it is because the stacking layer process that I’ve done before is incomplete and caused an error, and now the problem is solved! thank you.

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