Jump to content
PDS Geosciences Node Community
Subhabose

Overlay M3 and RELAB spectra

Recommended Posts

Hi!

I want to compare spectra generated from M3 with RELAB library spectra (62231, Apollo 16 landing site soil sample) using ENVI. One specific issue is, spectral library from RELAB (62231) has 451 bands, whereas M3 has 86 spectral bands. This is apparently creating a mismatch and is not allowing me to compare the two spectra. 

Please help!     

Share this post


Link to post
Share on other sites

Greetings:

You can use both the new ENVI5 series interfaces or the Classic ENVI interface to a resample spectral data set to a new set of center wavelengths and, optionally, band passes. You will find the spectral resampling procedure under the toolbox on the right hand side of the ENVI5 series interface, and under the spectral heading on the pull down Classic menu. Next select an input data file (it needs to have wavelengths in the header record) that you designate as the new wavelengths for the spectrally resampled data. The dialog box then asks you for the output file that will be resampled. If there are band passes (like Gaussians) in the input data file header these will also be used in resampling the output data set. I just tried it with an OMEGA L data set as the input and one of the ENVI JHU spectral libraries as an example and it worked. It resampled the JHU data to the OMEGA wavelengths and made a new JHU spectral library. Also works with spectral cubes as input and output data sets, etc. Let me know if you still have some problems and we can talk on the phone.

Ray Arvidson

PDS Geosciences Ndoe Manager.

11/6/17

Share this post


Link to post
Share on other sites
On 11/6/2017 at 9:35 PM, Ray Arvidson said:

Greetings:

You can use both the new ENVI5 series interfaces or the Classic ENVI interface to a resample spectral data set to a new set of center wavelengths and, optionally, band passes. You will find the spectral resampling procedure under the toolbox on the right hand side of the ENVI5 series interface, and under the spectral heading on the pull down Classic menu. Next select an input data file (it needs to have wavelengths in the header record) that you designate as the new wavelengths for the spectrally resampled data. The dialog box then asks you for the output file that will be resampled. If there are band passes (like Gaussians) in the input data file header these will also be used in resampling the output data set. I just tried it with an OMEGA L data set as the input and one of the ENVI JHU spectral libraries as an example and it worked. It resampled the JHU data to the OMEGA wavelengths and made a new JHU spectral library. Also works with spectral cubes as input and output data sets, etc. Let me know if you still have some problems and we can talk on the phone.

Ray Arvidson

PDS Geosciences Ndoe Manager.

11/6/17

Hello!

Thank you very much for your reply!

I followed the steps mentioned using ENVI Classic and am sharing some of the results with you. 

First, I chose the 62231 ASCII file and converted it to a spectral library using the RELAB ENVI header file information, which I found here (https://lost-contact.mit.edu/afs/enea.it/software/rsi/envi_3.5/spec_lib/igcp264/igcp_2.hdr).

Once that was done, I tried to match the same with a small region that I was able to subset from one of the M3 (Level 2) images. Unfortunately, I am still unable to match the two spectra.

Please let me know where I am going wrong. 

For your convenience, I am attaching some screenshots.

 

Share this post


Link to post
Share on other sites

Here to help. I am not sure why you have a screen shot of a vertical profile, which suggests to me you opened the spectral library as an image. To examine the spectral library data you need to open the file as a spectral library, not as an image. Did you open it as a spectral library, and could you display spectra? If you did this and can display spectra, resampled to M3 bandpasses, you should be able to overlay spectra from an M3 cube pixel with the lab spectra. Let me know what you did and I can help more if the instructions above are not enough. Worst case is for me to try what you wanted to do with the exact data sets you used. 

Ray Arvidson

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×