CRISM Data Filtering

[Sehaj]

While using CAT toolkit, we go for cleaning (destriping and despiking for IR, and destriping for VNIR) the data. In Data Filtering, there are two alternatives:

1. CIRRUS>Clean spectral cube

2. MRO CRISM Remove Stripes

I see generally, CIRRUS method is preferred. What is the science behind cleaning by two methods. And which method should be optimum for me?

What if, I do not go for data filtering and simply georeference the image after photometric and atmospheric corrections?

Thanks in advance.

[Ray Arvidson]

Sehaj: Both of these apps are a out of date and are not needed with the TRR3 or MTRDR data sets. I suggest skipping their use. Do flatten your spectral parameter sensor space data before projecting.

Ray Arvidson

[Sehaj]

Thanks for this information.

I hope by flattening the sensor space data, you mean to say dividing the spectra by the spectra of neutral region in my image?

[Ray Arvidson]

I mean under data filtering ,choose  flatten summary products. This is because the spectral summary products vary from column to column. Flattening does some column wise smoothing to make a better product. Do this in sensor space.

Ray Arvidson

[Sehaj]

Okay..Many thanks!

[SHABANA EBRAHIM]

Hi sir,

I have a query on the same. If we are using a FRT data - either TRDR or MTRDR, what all image processing steps do we have to perform? Is flattening summary products ONLY required for MTRDR data (where as map projection for TRDR)?

Also, what does the "APPLY CRISM BADBANDS" functions for?

[Ray Arvidson]

Never flatten a map projected product. Flattening is only for sensor space products. Please read the Software Specification Document on the PDS site under CRISM to understand the nature of the various product types. For MTRDR nothing more than examining the spectra and associated products is required. For the TRDR IF products use CAT to do a volcano scan correction and map projection. Generate spectral parameters in sensor space, flatten them, and then project them. Then do your science.

Ray

[SHABANA EBRAHIM]

On 10/18/2022 at 10:36 PM, Ray Arvidson said:

Never flatten a map projected product. Flattening is only for sensor space products. Please read the Software Specification Document on the PDS site under CRISM to understand the nature of the various product types. For MTRDR nothing more than examining the spectra and associated products is required. For the TRDR IF products use CAT to do a volcano scan correction and map projection. Generate spectral parameters in sensor space, flatten them, and then project them. Then do your science.

Ray

Hi Sir,

As you told, I opened the MTRDR data in ENVI and directly opened the spectral profile without any processing. I opened different FRT data and their corresponding spectral profile seems to be the same. I have attached the screenshot for reference.  

I also have one more query. How to spectrally resample the data in ENVI?