Jim Bell Q'n'a 3, Feb. 15, 2006, Your questions answered! Options

[djellison]

Ahh - thanks to Jim for putting up that Super Res page - that's interesting to see, particularly as it's not really worth trying to do super-res with the JPG's.

Meanwhile - Jim's done a transit page as well...including higher-res version of my simulation Mov's

http://marswatch.astro.cornell.edu/pancam_...projects_4.html

Doug

[hendric]

Thanks. That's quite an improvement. I've read that the resolution can be improved by a factor of n^(1/2) where n is the number of images. For 31 images this would be by a factor of about 5.5. Anyone know what is the level of improvement in this case?
- Bob

That formula is only true for dark-sky photography. There you are trying to improve the S/N ratio, not the resolution, via stacking. I think here the amount of improvement is more related to the point spread function vs pixel size, at least that's the gist I got from the interview. Maybe a good question for next time on the details of how that works.

[tedstryk]

Yup - it's not as if taking 100,000 images would give you anything more than the 30 or so they did of the heatshield, and the 10-15 or so they did around the festoon targets.

I'm not sure how one might make a quantitative estimate on the improvement of resolution in that attempt I made on the Heatshield - it's not a lot though, certainly less than 50% improvement, probably more like 25 or less.

It takes features that are 'sort of' there, and brings them out just enough to be believable - I think that's the take Jim had on it.
Doug

And interpretable. A block of a few pixels can sometimes clearly be a crater after super-resolution processing. It is hard to tell what kind of improvement you will get. With sharply focused, high signal to noise ratio images, it depends how the rows of pixels intersect - the whole process is taking advantage of their not lining up exactly. Sometimes, this type of processing works miracles. Usually, it sharpens things up a bit, but most of the gain comes from the improved signal to noise ratio of the stacked image.

[mars loon]

These are quite helpful. Jim is a great guy, willing to help. ken

[odave]

My work is getting back to normal levels, so I can manage to do some more transcribing over my lunch break. I'll just keep chugging away at 5-10 minute slices. If anyone wants to jump in and do a chunk of their own, just holler!

==============
Pancam Update #3 - 2/15/06

00:00 - 07:59
=============

DE: This is Doug Ellison of UnmannedSpaceflight.com with the third pancam update on February the fifteenth, 2006. It is sol 734 for Opportunity, sol 754 for Spirit. And I started this time by asking some of the questions that we've had submitted via the forum and via the Planetary Society website. Unfortunately I have to apologise in advance for some slightly ratty audio. I'm not sure quite what happend, but I'll try and get it sorted for next time.

DE: We've had some qustions through via Emily at the Planetary society, and this is from Hendric in Texas. And something I've been wanting to know for some time and that is, how does the team feel about posting the raw images on the web? Does it seem, from time to time, that us keen amateurs are almost stealing your thunder and would you chuck images on the web for a future mission?

JB: Hm. Those are really good questions. Well, putting the images on the web like this was our idea, it's an idea that I had, and Steve Squyres and I talked about it very early on when we started thinking about how the whole data system would work and how data would flow through JPL. And both of us have had experiences, our colleagues have had experiences where we've been involved in big mission teams and seen...maybe the less-than-attractive side of people working in certain high pressure situations where they've got images to work with and feeling like they're constrained about sharing them with people. Both Steve and I believe very strongly that it's a privilege to be working on a project like this, and that part of what we're doing is beyond just the science, and what can sometimes be the esoteric geochemistry or geology or atmospheric science that we're doing. Part of what we're doing is exploration, part of what we're doing is sharing this incredible voyage of both vehicles on Mars, and the feeling of being there, and experiencing Mars for the first time with pancam's human eye kind-of resolution. And so that really was what allowed us to form these ideas of having the downlink, the data coming from the spacecraft literally split. Soon as it gets to JPL, it duplicates, and one path goes to a routine that automatically converts every image into a jpeg and posts it on the website as quickly as possible. And the other branch of that split goes to the science team and the areas where we do the processing and all that. And we had a lot of debates and discussion among the team about the value of doing this, ultimately the entire team is, almost the entire team is behind this, as far as I know...

DE: [laughs]

JB: ...we had a lot of discussions about how to do that jpeg scaling, because these are raw images. And there was some risk involved too, Doug, remember this is before we landed we decided we would do this, and we didn't know what the image quality would be like. Would we end up with crummy images being posted on the web in real time because something had happened to the cameras because of the landing shocks or whatever. It's all worked out beautifully. We've, I don't think any of us have regretted at all doing that. It is true that lots of folks, amateur Mars watchers, even some of our professional colleagues are "scooping" the team by looking at the images carefully by finding things in there or deriving relationships and all that. And actually that's fine, that's a small price to pay for being able to share this adventure with so many people. Would I do it again? I'd do it again in a minute. I'm involved in the MSL team and I'm going to make that argument with my colleagues on that team, that we try to do the same thing. Nothing's been decided yet, but I think we should try to do the same thing.

DE: I don't think you'd hear any arguments on that from our side of the fence [laughs].

JB: Excellent!

DE: Brian from Iowa has asked about the super resolution images. Are they being done in a way similar to that was done with Pathfinder, essentially taking multiple pictures with the camera moved very slightly, and as a subscript I'd add to that is it quite similar to, for instance, the stacking of planetary imaging you see amateur astronomers do.

JB: Yes and yes. The approach that we use is to point the camera at a feature, and then turn away and come back, and intentionally come back to a position just a few pixels up or down, left or right, from the original one. And therefore the features in the scene we're looking at don't end up on exactly the same pixels. And when you've stacked 15 to 20 images together that way, we can effectively increase our resolution. It's a process which astronomers call "dithering" - it's a very, very similar process. It's not exactly the same as what was done for Pathfinder because the optics of that camera were matched differently to that - the Pathfinder camera's detector. It was, I could get into some esoteric detail about point spread functions, but suffice it to say that we knew ahead of time that super-res in the Pathfinder approach wouldn't work like it did for Pathfinder, for the Pancams, because the pixel scale is a much closer match to the point spread function. So we knew that we could only expect a relatively small improvement, but we do see that small improvement. I was maybe one of the biggest skeptics early on, and a few folks on my staff, a guy named Joshua[?] Sohl-Dickstein who worked with me on this early on proved me wrong. He developed these algorithms that are published in our 2006 JGR paper that...just look at the images. Yes indeed, you can see very subtle detail, improvements in the resolution with our super res sequences.

DE: How much of an improvement, do you reckon, as a percentage? 50% better, or...

JB: No, I think it's in the 10's of percent, I think it's a small improvement. And I think it's especially an improvement for lineations and small scale features, small blueberries in the Opportunity images, for example. Small laminations in the rocks. Those kinds of features that are already at the limit of resolution of the camera I think can be made believable by this technique. It's extremely rare that we can see brand new things pop up, in fact I don't know of any cases where that's true. You can take a singe, normal, pancam blue filter image, which is the maximum resolution of the camera, and play with it in Photoshop with some sharpening and edge filtering and you'll probably see the same things, if you would, in a super res sequence after we've done our processing. But it's more defensible and...

DE: More believable...

JB: ...easier to believe, exactly. That's the right word. Easier to believe and defend it with our colleagues when we point to it in a super res sequence and say "look, this is using a well established technique that astronomers and others have used for a long time, and you can believe these features.

[odave]

Pancam Update #3 - 2/15/06

08:00 - 15:53
==========

DE: Going back what seems a very, very long time, I remember super res sequences being done of Spirit's heatshield from across Bonneville crater, and Opportunity's backshell and parachute from inside Eagle crater. What were the results like for those?

JB: Well those were pretty difficult situations, because both of those objects were very distant. We tried it just to say that we could get the maximum resolution, because we knew in both those cases we wouldn't be going to the heatshield or the backshell. And so we wanted to do the best we could. I think in the case of the...my recollection...you're right it's a long time ago

DE: Very long time [laughs]

JB: [laughs] My recollection is that the backshell imaging did bring out some additional detail but it's nothing like you would want to do an engineering characterization, things like that. It really was to help refine our positioning for triangulation, just to do the best we could. But we really don't have good characterization of either of those, the backshell on Spirit or the heatshield on Opportunity.

DE: One thing I've certainly found with Spirit's heatshield, I had a go when the raw JPEGs came down, and because of the compression that goes in with the JPEG, I got barely any results at all. But, six months later once the proper data was available to the public, I had another go, and the results, actually there was definitely an improvement on the image from a single frame, but you didn't get just by using the compressed JPEGs.

JB: That's a good point, those are JPEGs that are going out in real time. And the agreement that the project made with NASA was that all of the, what you say the "real data", get released within six months, because there's a process that we go through - it's called validation - and of course calibration to remove the instrument artifacts that we spent so long before launch characterizing. And then the data have to get formatted, and the labels and headers have to be put on correctly, and everything has to be double-checked. And that's kind of an administrative, bookkeeping...some people refer to me as a "data janitor" sometimes because you end up doing these kinds of things. But all that checking has to be done before we release the data, because once it's out there, it's not coming back. You can't delete it and replace it, so we try to be very careful about that. But your point is well taken, you really have to be careful with the JPEGs just like any other JPEG that you pull off the Web, and worry about compression artifacts.

DE: Now let's move on to what I thought we could tackle as a main theme this time, which is "The Big Ones", the big panoramas. There was specifically a panorama section on the pancam website different from a favorite image section. Do you have a set definition for what does or doesn't constitute a panorama, over just a big mosaic?

JB: You know, that's a really good question. I don't have a set definition, I guess the trend is that if it's 360 degrees, or close to 360 degrees, we'll call it a panorama. Whereas if it's a 2x2 or a 4x3, more of a postcard, something like that, we won't call it a panorama, we call it a mosaic. But it's a fuzzy line...

DE: It is...

JB: ...you know, "is Pluto a planet?", you know...

DE: [laughs]..."is that a panorama?" Yeah.

JB: Exactly.

DE: The line in the sand that I draw is anything that's 120 degrees or more, two frames tall or more, is a panorama rather than a mosaic.

JB: Mmmm hmmm

DE: That's my line in the sand, but you could draw it anywhere, really.

JB: Exactly. And it doesn't, you know, really matter...

DE: No, no - no

JB: ...a panorama by any other name would look as sweet, right?

DE: [laughs]

JB: ...to quote one of your countrymen.

DE: [laughs] Yes.

JB: What we are doing is trying to post as many of our...let's just call them "large color images"...

DE: [laughs]

JB: ...as possible on that website that you mentioned, on the pancam home site. And we are woefully behind but slowly catching up. In fact I am probably the biggest bottleneck because I like to very carefully go through the...looking at the seams, looking for problems, and making sure that I'm happy with the color calibration. Sometimes I miss things, but that unfortunately makes me somewhat of a bottleneck in this process. But over the coming weeks, two months, I think you'll see that page grow as we clear out the backlog.

DE: Is there an element of frustration in the way that the press focus, astonishingly, on the mission success panoramas, but ironically, they are the panoramas of the poorest quality of all the ones that have been taken?

JB: [laughs] That's true! I mean, you have to remember or realize that we were in a very different mode of operations when we landed, right? And we didn't know that the Odyssey or MGS UHF passes would work, and so we had to assume that they wouldn't. They were a great experiment. Maybe they would work, maybe they wouldn't. But the nominal plan was that all of our data would probably have to come back through the high gain antenna, which is a much slower data rate. So we used very high compression, we used downsampling to make the images smaller, we would send down a "decent" red version and then downsample the green and the blue, for example. That seems like three million years ago to me now, to have that kind of a mindset. And because of the incredible success of the daily Odyssey passes and the early MGS passes, we've quadrupled, quintupled our data return from this mission. And the big spender there, of course, is pancam for almost all of those extra bits. So yes, it's a bit frustrating that those are becoming sort of iconic images, but I think, you know, certainly in textbooks and websites I'm seeing lots of other of our greatest hits images show up since then. Some people's backgrounds on their desktops at the local Starbuck's, I'll see a pancam picture and kind of smile. If you'll let me digress for a moment, I think I have a little more frustration with just the media coverage in America in general over the missions. I mean, there's this incredible adventure going on, on two sides of Mars every day, and there's very little coverage. When something breaks, we get some coverage, when we pass a milestone like the anniversaries that came and went recently, we get some coverage. But I've found that the coverage outside of the U.S. is much more extensive than actually inside the U.S. Which is a little bit of a shame.

DE: I spoke to one of the people who works on "The Sky at Night", it's a very long running television series here in the U.K., and he said they've always been wanting to do an MER special, just about MER, for "The Sky at Night", but they keep waiting for them to stop working before they do it because they don't want to miss anything.

JB: That's right, that's right. I suppose that's when we'll get a lot more coverage in the U.S. media is when one or both of them do finally die. And they will, nobody still knows when, but all good things must come to an end.

This post has been edited by odave: Apr 11 2006, 05:22 PM

[odave]

Pancam Update #3 - 2/15/06

15:54 - 26:18 (end)
=============

DE: If you do a rough count, there's about - using the line I've drawn - there's about 19 panoramas from Spirit, but only about nine from Opportunity. What does that say about how different the two experiences have been on the opposite sides of the planet?

JB: Well, I think it says that once you get out onto the plains of Meridiani, life is pretty boring. I mean, you've seen the Rub-al-Khali panorama and others that we've taken being out on the plains, there's just nothing to see. Taking a large panorama, using all those color bits at high resolution just doesn't buy you anything in terms of the scientific return or even just the vista, it's the same vista once you're out on the plains. It's only when we back off from Eagle Crater and took that beautiful view looking in, only when we got to the rim of Endurance Crater and we took those beautiful large panoramas, when we sat at Erebus Crater for the last few months taking a series of large panoramas there. It's when we see something new, that is different, and that happens much more often on Spirit, it's because of the nature of the terrain, than at Opportunity.

DE: Is there, looking back over this very long time, a little sequence, a little mosaic, or just a little frame that you couldn't or you didn't take, you'd like to pop back 500 sols and take a picture that you couldn't at the time?

JB: [laughs] That happens almost every day! [laughs]

DE: [laughs]

JB: You know, some days you're very constrained in terms of power, some days we don't have the bits, some days we don't have the time to do the scenery justice, to do the science part of the imaging justice. A good recent example has been our run from El Dorado to Home Plate at Spirit. We flew almost as fast as we possibly could with that rover past some amazing vesicular basalts and ridges and other really interesting deposits. And we were just trying to grab what we could in the pictures and the infrared spectra, but the goal...we were driven to get to home plate because of the winter that's coming, and we need to do some preliminary characterization, at least, before we have to get ourselves in a situation, orientation where we can survive the winter. So there was a whole span of several weeks where if we hadn't been in that rushed mode because of survival, we certainly would have done a different job of characterizing the terrain. That's the reality of operating these vehicles, is that you're often constrained from doing what you would really like to do. Still, within those real world limits of operating rovers on another planet, I think we're doing an O.K. job.

DE: Not *too* bad...

JB: Not too bad.

DE: It's only partially down but the Gibson Panorama is, I'm guessing, about 180 degrees, about three frames tall, looking at what is the northern side of Home Plate. And...I'm almost doing the classic media thing here...what's your take on what it looks like so far? What do you make of Home Plate?

JB: Well, we designed it very similarly to the panorama that we took at Burns Cliff. And you're right, it's about 180 degrees, five or six filters, and you're also right that much of the color data is still onboard, it's sort of slowly trickling down day by day. Home plate has a lot of us scratching our heads. It is, of course we're delighted and thrilled and giddy to see this kind of amazing layering for the first time. I mean, we saw hints of it, right? At Jibsheet, with the small rock in Tetl, in the Columbia Hills. This is a different kind of thing altogether. I have to pinch myself some days when I look at the images and remember that I'm looking at Spirit images, not Opportunity images.

DE: Sometimes you think someone snuck a picture from Endurance Crater...

JB: Exactly...

DE: ...into a new Spirit folder, it's extraordinary.

JB: Exactly. Now one thing that has been...it's been slow to acquire the elemental chemistry and minerology data, partly because we're so many half lives into the Mossbauer source, it takes much longer to integrate and collect good signal. And also there's been some issues with positioning correctly against the features and all that. So I have not seen...and we haven't had a lot of intense debates yet about the details of the composition, but I have not seen evidence that we are looking at high sulfur deposits and things like what we see at Eagle or Endurance Crater. I think these are ultimately volcanic deposits that have been altered in some way, modified partly by wind, no doubt, perhaps also by water. I mean we're having basic, fundamental debates about whether Home Plate is a volcanic feature or an impact feature, and how it has subsequently been modified. The fun of this is being able to frame those questions and those debates in terms of specific hypotheses that we can test with the rover. We can look at the orientation of certain layers, we can look for certain kinds of features in the pancam data or the microscope data. Ultimately we're going to climb up on top and try to figure out the mystery of why does this material look bright from orbit, from MOC images. So I would categorize the current situation as still puzzling, but we do have some hypotheses and we're going about in the sort-of scientific way of testing them, and posing them, testing them, shooting them down and coming up with new ones. It's still gonna take time.

DE: How long do you think you'll be able to spend at and around Home Plate before running up to do some winter sunbathing?

JB: Yeah, realistically I think we're only looking at another week or so of being able to be here before the engineers and managers and many people on the science team reach their comfort threshold. It hasn't been decided exactly where we're going to do that wintering over, how we're going to do it. But we have to because more important than anything is keeping the rover alive if we ever hope to come back and explore Home Plate in more detail. And I think that's an option that is certainly on the table. This is such a sweet and juicy spot that, just like you would out in the field, it's totally reasonable to assume that you can turn around and come back to revisit a place after doing something else. In this case the "something else" that we have to do is to keep the rover alive. So we really don't have any choice.

DE: Meanwhile, as a mission manager report would say, on the other side of the planet, Opportunity looks, to the uninformed amateur, that it might finally be ready to take some decent steps southward. What's the story?

JB: Yeah, well as the mission manager reports have been indicating, we're sort of finishing up our activities at the rim of Erebus Crater. We had this long hiatus because of the problems with the shoulder joint. But the engineers and the rover drivers and the mobility folks have come up with a strategy for driving in this environment and with the reccommended way to operate the motors. We have since...since learing about their reccommendations, we've put together several campaigns with the microscope and some of the other instruments on these amazing rocks around us. We've found those festoon crossbed features which we think are much stronger evidence than what we saw in Eagle or Endurance for liquid water at the surface, shallow liquid water. And we've had some press release images about that. And we're pretty much done doing just about everything we can and want to do at this site, so we're hoping to hit the road as early as today or tomorrow to head over to some vistas for the rest of...other parts of Erebus Crater. And then, of course, what everone wants to do, and that is hit the road south a few kilometers to Victoria.

DE: So a likely stopover at, I think it's Mogollon Rim, just to the south, on the way?

JB: Yeah, I think it's going to depend on what the view really looks like and the details of how the traverse is going to happen. Of course there is still a lot of concern about getting bogged down in sand, and so we want to stay on outcrop as much as possible, and that's an overriding concern compared to, in some cases compared to getting detailed images of other parts of Erebus. So it really depends on the path that the rover drivers come up with, and how safe it is, and how close it takes us to other targetted parts of Erebus Crater. So stay tuned.

DE: So, that's it for the third Pancam Update. Of course I'd like to thank Jim Bell for answering our questions, and I'd like to thank Emily Lakdawalla and The Planetary Society for hosting this file. If you have any questions you'd like to have asked in the next Pancam Update, then send them to blog@planetary.org and I'll try and get to them next time around. I'll speak to you again soon.