[ldd-img] Responsivity units

[rgdeen]

Recently we added Spectral_Radiance as units: W/m**2/sr/nm.

However, the img:responsivity_r/g/b/pan attributes are actually in terms of what we call responsivity, or perhaps a good name is "Spectral_Responsivity"? This is a function of exposure time, and converts the DNs from the sensor to spectral_radiance units. As such, the unit is really Spectral_Responsivity/(DN/sec), or W/m**2/sr/nm/(DN/sec).

Note that I made up the "Spectral_Responsivity" name; I don't know what this is called generally or if in fact there is a generic name for it. It's disturbing we can't just put in arbitrary combinations of SI units. DN is not really an SI unit but it is legal as Units_of_Misc currently.

So is it possible to get this in for use with Mars2020? It might require a pds core point build, or some such. If so, the responsivity_r/g/b/pan (but not responsivity_factor*) should be changed to use this unit. But only if. The alternative is to just put the unit in a field.

Note that we need a decision on this ASAP as the RDR Peer Review is in a couple of weeks, and we need to know which way to go on the labels. Thanks.

[thareUSGS]

Jira won't let me in right now to check if similar issue has been addressed. I know any approved SI unit is allowed just not sure on more custom. I am not an unit expert here though - maybe @acraugh or @mit3ch have some advice? If anything, I would think "W/m**2/sr/nm/(DN/sec)", might be allowed under Miscellaneous_Units, but I do think it might need a quick SCR to get it approved. Lock-in to pass new issues is Jan 17 for the next build cycle. I will also ask the DDWG (this Thursday) if we don't have a path forward before then.

[myche]

Do we need an SCR for tomorrow's DDWG or will we find out then if we actually need such an SCR?

[mit3ch]

Hi Trent,

I’m not sure this is the definitive answer. I believe you will want to submit an SCR (using the short form). CCB-251 is an example of a request to add a unit of measure.

BTW, I don’t know which browser you use. While Firefox prohibits access to a site with a flawed or expired certificate, Chrome’s “Advanced” option gives you the option of entering the site anyway.

Mitch

From: Trent Hare notifications@github.com Sent: Tuesday, December 1, 2020 7:14 PM To: pds-data-dictionaries/PDS4-LDD-Issue-Repo PDS4-LDD-Issue-Repo@noreply.github.com Cc: Mitch Gordon mgordon@seti.org; Mention mention@noreply.github.com Subject: Re: [pds-data-dictionaries/PDS4-LDD-Issue-Repo] [ldd-img] Responsivity units (#139)

Jira won't let me in right now to check if similar issue has been addressed. I know any approved SI unit is allowed just not sure on more custom. I am not an unit expert here though - maybe @acraughhttps://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Facraugh&data=04%7C01%7Cmgordon%40seti.org%7Cc7ec4f971b5742dcd4ca08d896572179%7Cdeac5258294749c2a474e8ab151104fb%7C0%7C0%7C637424648264528933%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=FfbrGPetRR0%2BT4Y1Yfuu%2BQAgzCgmbF0GlZHGn2qPFvM%3D&reserved=0 or @mit3chhttps://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fmit3ch&data=04%7C01%7Cmgordon%40seti.org%7Cc7ec4f971b5742dcd4ca08d896572179%7Cdeac5258294749c2a474e8ab151104fb%7C0%7C0%7C637424648264528933%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Mgtlvqy3Lr9N2ljzf8ta8zoME995V1cpjgPOOnNR9l4%3D&reserved=0 has some advice? If anything, I would think "W/m**2/sr/nm/(DN/sec)", might be allowed under Miscellaneous_Unitshttps://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fsbndev.astro.umd.edu%2Fwiki%2FUnit_Classes_Standard_Values%23Miscellaneous_Units&data=04%7C01%7Cmgordon%40seti.org%7Cc7ec4f971b5742dcd4ca08d896572179%7Cdeac5258294749c2a474e8ab151104fb%7C0%7C0%7C637424648264538931%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=EB6MS1KXffeEmy2fD82bOJLrOj%2FrU%2BLtRt2ytbjM6W4%3D&reserved=0, but I do think it might need a quick SCR to get it approved. Lock-in to pass new issues is Jan 17 for the next build cycle. I will also ask the DDWG (this Thursday) if we don't have a path forward before then.

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[rgdeen]

If the next build is Jan 17, can we use it for 2020? PR is going out in a couple weeks. I guess as long as we have a decision by next week we can do it "on spec" for the PR?

[thareUSGS]

I will try to capture this in a new SCR. BTW, the Jira site is back up.

[thareUSGS]

rgdeen the original text is a little confusing (which term means what). I have a new SCR for the DDWG but it is stated as (below). Does this make sense and meet your needs? Note options for Spectral Radiance units are defined in PDS4 here: https://sbnwiki.astro.umd.edu/wiki/Unit_Classes_Standard_Values#Spectral_Radiance

Problem Statement: Mars2020 has the need to define a new unit for "spectral responsivity", specifically 'W/m**2/sr/nm/(DN/sec)'.

Requested Changes: Add to 'Miscellaneous_Units' the value of 'W/m**2/sr/nm/(DN/sec)' -- also called 'spectral responsivity'.

Description: spectral radiance is generally represented using 'W/m**2/sr/nm'. Mars2020 however stores pixel values in terms of "spectral responsivity". This is a function of exposure time, and converts the DNs from the sensor to spectral_responsivity units. Thus they are calling this:

Spectral Responsivity = 'Spectral_Radiance/(DN/sec)' or 'W/m**2/sr/nm/(DN/sec)'

BTW, I will be looking for this unit from PDS3 archives. Do you recall this unit being used before?

[rgdeen]

Correction to Description:

Description: spectral radiance is represented by M2020 using 'W/m*2/sr/nm'. The calibration parameters however are also a function of exposure time, thus they are expressed as responsivity = Spectral_Radiance/(DN/sec) meaning that spectral_radiance = DN responsivity / exposure_time. The addition of spectral_responsivity allows these calibration parameters to be stored in the label with appropriate unit designations.

Note that there are a number of options for spectral_radiance with different units... so in theory there could be a bunch of responsivity units too. But for all recent Mars missions all we need is the one, W/m**2/sr/nm/(DN/sec) so I'm okay just adding that, and others can add more if needed. Seems kind of silly to define them all at this point.

[thareUSGS]

@rgdeen To tie this one up for a vote, can you post an example label (section) using this value? I think that will help clear it up for others.

[thareUSGS]

W/m**2/sr/nm/(DN/s) was approved by DDWG and off to CCB review. Timing is another thing. As this is in the main IM (information model), we might not see it available until IM 1.G.0.0 is released.

[thareUSGS]

CCB passed this also. This option will be available in PDS Information Model v1.G.0.0