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Right processing workflow for TRDRs and others


Wladimir Acevedo
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Hi community, 

I'm working with ENVI 5.3 + IDL coupled with CAT 7.4 trying to process TRDR images (.trr3). I'm based primarly on the CRISM data processing workshop from 2012 and 2017 and my worksteps are as follows:

1.- Apply the ATM  corrections with CAT to the images
2.- Apply de map projection fo the image
3.- Obtain the summary parameters image

Nevertheless, I have certain doubts about this, so I would be very grateful if you can provide me some help please. My questions are:

- Should I obtain the summary parameters and then apply the map projection or it is the opposite?
- It is necessary the "ratioing" for the spectra and use the "Flatten summary parameters" option?. I've seen a post where its says that is enough the "Continuum Removed" option
- How can i obtain a better resolution for the summary parameters image?. I've seen very good resolution images from papers that doesn't look like what I have obtaining (img_1)
- When I create the summary parameters image  the spectra doesn't look like the TRDR pure image because the data values change. Does that mean that I have to use the spectra from the TRDR and the summary parameters image is just like a "color guide" fot the mineral phases? (img_2)

Finally, how can I use the summary parameters properly and elaborate mineralogical maps from they?

Any help will be very appreciated, thank you.

Wladimir
wladimiracevedo@udec.cl

img_1: The resolution that I'm getting from the summary parameters image after the custom stretch
img_1.thumb.PNG.ca0cc8eb430e04105c794d27294ed4d7.PNG

img_2: Spectra for the summary parameters image vs the original TRDR corrected image from the same pixel on both.
img_2.thumb.PNG.32669165bccf65d3e8ece47a768506ed.PNG

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Hi Wladimir,

 

This is Feng, I will try to answer your questions:

Should I obtain the summary parameters and then apply the map projection or it is the opposite?

Basically they are identical. For my opinion, I will do map projection then summary parameters since it reserves the summary parameters band name.

image.thumb.png.f06e743d6eb4a293a1bd4a25a84b10de.png

It is necessary the "ratioing" for the spectra and use the "Flatten summary parameters" option?. I've seen a post where its says that is enough the "Continuum Removed" option

Sorry I don't understand this question. I will take the team scientist about this.

 

- How can i obtain a better resolution for the summary parameters image?. I've seen very good resolution images from papers that doesn't look like what I have obtaining (img_1)

The summary parameters doesn't change the resolution. For this product, it is 18m/pixel.

Here is all CRISM EDR resolution:

https://ode.rsl.wustl.edu/venus/pagehelp/quickstartguide/index.html?crism_edr.htm

For some Along-track oversampled (ATO) Spatial pixels unbinned for target – 18 m/pixel cross-track, up to ~3 m/pixel downtrack, requires special processing for increased resolution; half swath length as above.

For img-1, if you only select one band (BDI1000IR), you can see

image.thumb.png.d981b6e7885200f5aec350002a1adc6a.png

 

When I create the summary parameters image  the spectra doesn't look like the TRDR pure image because the data values change. Does that mean that I have to use the spectra from the TRDR and the summary parameters image is just like a "color guide" fot the mineral phases? (img_2)

Yes. For your attached Img-2, the index is not the wavelength but the summary parameters band:

image.thumb.png.018e651aec3d5679624c7a127f860cb2.png

Finally, how can I use the summary parameters properly and elaborate mineralogical maps from they?

For the summary parameters, you can read the following paper:

Revised CRISM spectral parameters and summary products based on the currently detected mineral diversity on Mars

https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014JE004627

 

Hope this helps.

 

Thanks,


Feng

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