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Complete Near-Infrared Spectrum


Rochdi
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Hello, Expert.

I have downloaded CRISM TRDR dataset concerning Ritchey crater. Then, I've implemented CAT extension in order to do some photometric and atmospheric corrections as well.
As known, the TRDR dataset broken out into two ranges:

  • VNIR (0.3646 - 1.0560) and includes 107 bands.
  • IR (1.0014 - 4) and includes 438 bands.

I want to split up those ranges to Visible, Near-infrared and Short-wave infrared into these following wevelength:

  • Visible (400nm to 700nm)
  • Near Infrared (700nm to 1300nm)
  • Short-wave infrared (1300nm to 3000nm)

It means if I split up CRISM VNIR range into visible and NIR spectrums, the visible spectrum starts from band7 to band53 (band7: 0.4036 - band53: 0.7032) and the rest of VNIR bands will be considered as NIR spectrum. However, the NIR spectrum extends till 1300nm and VNIR's last band wavelength is 1.0560, meaning that NIR needs some additional bands to be completed.

My question: Can I take some bands from CRISM Infrared range to come up with a complete NIR spectrum?

Look forward to your reply,

Rochdi.

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hi Rochdi,

My suggestion is that you merge the S (VNIR) and L(IR) cubes into one and then slice them to what you want.

The S cubes and L cubes have minor offsets. To merge them, you have to register one another. And then use attached IDL code to merge them. Following are detailed steps:

1, download the CTX covers the S/L cubes area in ODE (using Geotiff format CTX product)

for example using crism trdr (frt0001176e_07) as example:

  • first search frt0001176e_07 product then show result on map, you can see frt0001176e_07 area on the map;
  • select CTX layer; on map display, draw a rectangle to cover this area using "Select Products with Rectangle" tool;
  • download the CTX product in Geotiff format for exmaple (B07_012228_1427_XN_37S039W.tiff)

2, in CAT doing map projection for both S and L cubes

3. register map projected S and L cubes to the CTX product by using "Image Registration Workflow"

image.thumb.png.ea08300752fc5ff3c10bc09b8b8b775d.png

Manually select tie points (I select 9 tie points ) between CTX and TRDR:

image.png.5829c458e4d258d9a8c79d07ed96fd66.png

image.thumb.png.78a9f30fe47d83d597d27cd5d3e9b842.png

4, rename the attached SL_alignment_v5.txt to  SL_alignment_v5.pro and open it in IDL,  In IDL interface, click "Run', it will ask you select L cubes (results from step 3) , then select S cubes (results from step 3) and output the merged data. Now you have the data covers from 0.3646 to 4. You can select bands you need to export a subset data.

 

image.thumb.png.7b3604bbe2143bab8d19d02f4a2ab029.png

 

 

SL_alignment_v5.txt

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