Forums

March 13, 2025 - New MEX HRSC RDR Version 4 data loaded into ODE -    Added HRSC new radiometrically calibrated (RDR version 4) image data into ODE, with coverage from August 6, 2024 to December 29, 2024 (Orbit 26500). ODE product search page: https://ode.rsl.wustl.edu/mars/productsearch ODE map search page: https://ode.rsl.wustl.edu/mars/mapsearch ODE data holdings page: https://ode.rsl.wustl.edu/odeholdings/Mars_holdings.html

Hi Tejay,   I've confirmed your assessment that the BD1900_2 values reported are actually calculations for BD1930, instead. I've also tracked down the issue with BD1900R2 - in the SU file you referenced, the slopes for RC#### were calculated using R1815 and R2132, instead of R1850 and R2060.   Your calculations for BD1900_2 and BD1900R2 are correct, so I would recommend you keep using those. I'll reach out to the CRISM team regarding these issues you identified in the parameter calculations so we can get them corrected.   John

Hi Tejay,   Thanks for bringing this to our attention! There's definitely something odd going on with those two parameters in the SU file you referenced, and I agree with your initial assessment that the BD1900_2 values reported look like they're reporting BD1930, instead. I'll look into this in more detail, and report back here once I figure out what's going on.   John

Upon looking in this further, all BD1900_2 seems to be returning is BD1930:   The error between BD1900_2 as per the CRISM DPSIS documentation is this: But when I just return BD1930 instead:   Is anyone able to verify my suspicion. The next question is how is BD1900r2 really calculated as that one is going to be a lot hard to tease out?

Hi All, What I am seeking to do is to replicate/verify the calculation of the various bands contained within su164j MTRDR files and apply the same calculations to spectral data of minerals from a lab so I can compare like to like thereafter. I can replicate all of the MTRDR bands I have selected from the su164j file (with convincing accuracy) via the spectral data contained in the if164j file – except for BD1900_2 and BD1900r2 and thus the reason for my post. I am wondering if anyone else has tried to replicate the same and found an error with the specified formula? I have found an error in the CRISM DPSIS when trying to replicate other bands via cross referencing different sources… but this one I can’t resolve. I've detailed all my calculations: The formula From the CRISM DPSIS document:   The data From the file frt0000b385_07_su164j_mtr3.img and cell reference [580,595] I get BD1900_2 = -0.009848237. I am now going to try and replicate this result using the spectral data contained within frt0000b385_07_if164j_mtr3.img.   Kernel Width As I understand it, I need to retrieve the five closest wavelengths to 1850, 1930, 1985 and 2067, extract the reflectance values and calculate the median, this is as follows:   Calculating "a" and "b" values: The formula for this is: However, I could interpret this in 3 ways:| 1) Ideal - Stick strictly to the formula in the CRISM DPSIS document and use the wavelengths of 1850, 1930, 1985 and 2067; OR 2) Closest to Ideal - Use the wavelength closest to those ideal wavelengths, so for example instead of 1850 I would use 1848.95; OR 3) Median - Use the wavelength corresponding to where the median reflectance value come from in the case of R1850:5 that would be 1842.34. Calculating all 3 possibilities gives:   Calculating BD1900_2 Following the formula for BD1900_2 from there, with the 3 possibilities for the calculation of "a" and "b" gives:   Results discussion As per the file frt0000b385_07_su164j_mtr3.img at cell reference [580,595], the value of BD1900_2 is -0.009848237. Trying to calculate the same, but from first principals via the spectral data contained in the file frt0000b385_07_if164j_mtr3.img does not give the same result - not even the same sign... in fact for any cell there is a concerning difference between the BD1900_2 values in the su164j file and that calculated from the if164j. With other bands, I can pretty much reproduce nearly identical result (to 6-7 decimal places typically), which leads me to ask: - Is there a typo or something in the stated formula for BD1900_2 that is preventing me from replicating the same? Attached are my excel workings if someone can assist. Note: I am a Financial Math Masters student whose designated research project is identifying minerals on Mars via machine learning so if my lingo is not up to scratch, it's because just 5 weeks ago I didn't have any clue about spectral data! Thank you!! BD1900_2.xlsx