MEX VMC - Back on, and online! Options

[djellison]

I heard about this 24 hours ago, and couldn't believe it - this is EXACTLY what has been missing from ESA. MASSIVE kudos to the ESOC MEX flight ops team for doing it

http://www.esa.int/SPECIALS/VMC/index.html

The last time I wrote a post and hit 'submit' at UMSF with a smile this big on my face, was when Oppy successfully got out of Purgatory.

[djellison]

FWIW - I've attempted to debayer a tiny piece of image, by hand (using a 90x1 pixel selection again and again, to select alternate rows to cut them to a new layer - then again on columns, to split it into 4 layers. Then, I figured out which were the blue ones ( the darkest ) and from that established the red and the green. I then duplicated those layers to fill out the 2x2 pattern, and then copied into channels on a new image.

Hopefully someone will figure out a better method of doing this

[djellison]

I THINK I got a bit cleverer in making selections - this may or may not be accurate.

Attached thumbnail(s)

 

[Stu]

ESA often get a hard time here for what they do - or don't do - but this is a BIG step in the right direction, and shows that ESA really are trying to do more with the wealth of data and material they have. As Doug said, congratulations to everyone involved, and here's hoping the site attracts a lot of attention, not just from dyed-in-the-wool spaceflight enthusiasts like ourselves, but from the public too. Will definitely be worth keeping an eye on, looking out for great images. I can hear my hard drive groaning already...

And yaaay! An ESA crescent Mars image at last!!! Great job!

[PDP8E]

I always though that the Lunar Prospector team was absolutely CRAZY by not taking any type of camera to the Moon.

They did manage to bring an Alpha Spectrometer, Electron Reflectometer, Magnetometer, Neutron Spectrometer, and a Doppler Gravity thing-a-ma-jig.

Lunar Prospector was in a low polar orbit! and not a single image.
Then they decided to crash it into the Moon's south pole!
Any snapshot from a couple hundred meters would have been iconic.

And now, if you are not a Lunar scientist or a UMSF'er, the impact of Lunar Prosepector (pun intended) is ZERO

Note to spacecraft all designers: this non-science type of camera (MEX-VMC) is worth putting on all future space craft.
This is outreach at its best. This is how to capture the imagination of that next person.

This camera represents how we all pack for any trip ...DONT FOR GET THE CAMERA....and unmanned space craft take the most amazing trips!

Bravo to ESA and the MEXMARS Webcam! (...tons of images in the VMC archive...!)

[ugordan]

Wow, great work, Doug. My method of making a Bayer mask in Photoshop doesn't exactly work as I'd hoped. A new approach is in order.

Here's a messed-around crescent view, with an ad-hoc color balance. Might be completely wrong.

[djellison]

I always though that the Lunar Prospector team was absolutely CRAZY by not taking any type of camera to the Moon.

Spinning at 12rpm does kind of making taking pictures a bit hard - and if you do some research on the long term history of LP...it had NO money - none at all.

Doug

[Tman]

Here's a messed-around crescent view, with an ad-hoc color balance. Might be completely wrong.

But absolutely a gorgeous perspective!

[djellison]

Oh boy oh boy


http://esamultimedia.esa.int/multimedia/vm...46/target0.html

[ugordan]

I'm gonna give it a go at writing an app for automatically converting the raw files into RGB. Doug, have you figured out what the exact Bayer matrix looks like, starting from top left - I'd rather not try reinventing the wheel?

EDIT: Nevermind, I think I have it figured out.

[Juramike]

Even better, it looks like they'd like submissions of your best images!
http://www.esa.int/SPECIALS/VMC/SEMANKXIPIF_0.html

BTW, here is the syntax for the filenames of the individual jpeg images:

YY_DOY_hh_mm_ss_image-sequence-number.extension

For example: 08_213_14_25_16_vmc_img_no_8.jpg was:

* Taken in 2008
* On Day of the Year 213 (31 July)
* At 14:25:16 (hr:min:sec) UTC
* And is the eighth image taken in a series

Go ESA!

[Could they please do this for Venus too?]

[Paolo Amoroso]

Does the Picasa logo on VMC images imply that they are hosted at the popular photo sharing site? If so, double kudos to ESA.


Paolo Amoroso

[ugordan]

I've got a basic app going, it performs a rudimentary interpolation (if someone knows of a good de-Bayer algorithm, I'm open for suggestions) of the RGB data. When I clean it up a bit and sort out a command line interface I'll release it. Any requests in the meantime?

In the meantime, two gif animations:

A crescent (2.3 MB) and a partially overexposed north->south flyover (3 MB). Looks like the camera could benefit from a flatfield frame, if one were to be made. For some reason the RAW frames appear to be truncated in the ZIP archives, the last frame the most.

[Tman]

Very nice Gordan!

What could that illuminated be behind the terminator http://esamultimedia.esa.int/multimedia/vm...20/target7.html

Something atmospherical or even one of the volcanos that get also already sunshine?

[Paolo Amoroso]

Does the Picasa logo on VMC images imply that they are hosted at the popular photo sharing site?

Or maybe it's just a gallery generated with Picasa.


Paolo Amoroso

[Paolo Amoroso]

Are you able to use the Celestia scripts? I downloaded a ZIP file with images and the corresponding script, placed them in the same folder and run the script with Celestia 1.4.1 under MacOS X. But nothing happens.


Paolo Amoroso

[tedstryk]

[Could they please do this for Venus too?]

http://www.unmannedspaceflight.com/index.p...mp;#entry124259

[ugordan]

Nice catch, Tman! Looks like clouds to me, rotating into view over the terminator. Judging by the timestamps this would make the original imagery upside-down. Here's an animated gif (click to enlarge):

[djellison]

When I clean it up a bit and sort out a command line interface I'll release it.

Well that took AGES!

I'm happy to er.... 'beta test' it

Doug

[ugordan]

To be honest, coding that particular bit was easy. I find providing a command line interface is more tedious and boring work. I'd still like to implement a better interpolation technique, something similiar to what digital cameras do.

Anyway, a couple of new takeouts, these have saturation kicked up. I don't know why the original images look so desaturated.

[Stu]

Hmmm... why do the words "Kids", "new toys" and "Christmas" spring to mind...?

[djellison]

I was thinking 'pig' and err...'poo'

[slinted]

Kudos to the ESA and MEX teams! This is an exciting and inventive way to engage the public through existing hardware.

I'd still like to implement a better interpolation technique, something similiar to what digital cameras do.

Great work ugordan, it looks like you have these files well in hand. If you're looking for more advanced de-bayering, dcraw might be a good reference. It includes 3 different methods beyond bilinear. In terms of the color, do we know if there are any spec or calibration documents online? Pixel responsivity would be mighty helpful.

[Astro0]

..placed them in the same folder and run the script with Celestia 1.4.1 under MacOS X. But nothing happens.

Paolo,

I think that the intention with the Celestia script is just to show where MEX was at the time that the image was taken. Reading from their website it says that this will help users determine what surface features are visible and the timing of the images available. While the images are available in a folder of the same name as the script, I don't see that they are related beyond that. Simply a way to compare the Mars Webcam images to a visualisation of the same region using Celestia.

Astro0

[Paolo Amoroso]

I think that the intention with the Celestia script is just to show where MEX was at the time that the image was taken.

For each image, the script calls functions for selecting Mars and tracking it, which are supposed to bring the planet in the field of view. But I see only an empty star field. Also according to the script, the "M" and "N" should move to the next or previous image location, but this doesn't work. I don't see the instructions that the script should display, either.

Hmmm... I'd better check whether the version of Celestia I am using was compiled with support for the Lua language required by the VMC scripts.


Paolo Amoroso

[ugordan]

A dodgy first version of the tool:
 vmc2rgb_v01.zip ( 37.97K ) Number of downloads: 1658

It takes an input RAW file and writes out a PNG with the same filename and adds a "_rgb.png" suffix. For example:

CODE

VMC2RGB "08-183 12.23.52 VMC Img No 6.raw"

will produce "08-183 12.23.52 VMC Img No 6_rgb.png". Note that in windows command line prompt you need to use double quotes for filenames containing spaces such as these. The end qoute is not strictly necessary. If you associate the *.RAW file extension to the program (or if you just drag-n-drop the image on the program icon) you don't have to worry about this.

Also, the tool is dumb in that it will interpret any file you feed it as a 640x480 raw stream. I suppose I could make it grab PNGs as well sometime.

I'll consider adding an improved interpolation as slinted suggested later. I've done some reading and apparently the Bayer filter outputs have a fair amount of inter-channel "crosstalk" that causes saturation to go down which might explain the low saturation in these images. This is usually automatically handled by digital cameras with internal saturation boosting, in this particular case Photoshop's your friend.

[Paolo Amoroso]

Hmmm... I'd better check whether the version of Celestia I am using was compiled with support for the Lua language required by the VMC scripts.

I've checked, the Celestia version I am using does support Lua.


Paolo Amoroso

[Astro0]

Paolo, see if you can download Celestia 1.5.0. It runs the .cel script with no problems (perhaps a little slow to start, but then it hums along).
Astro0

[jekbradbury]

For those who would rather not manually run each of the 80-odd VMC pics through the demosaicker, here is a 16Mb zip of all VMC images to date demosaicked and PNGified with vmc2rgb:

http://www.filedropper.com/mexvmc

These images remind me of the early Mariner pics of Mars: albedo features, maybe a mountain or two, with some craters thrown in. It's also interesting how the CCD has a Bayer filter, yet the main use of the camera did not require color capabilities.

[Paolo Amoroso]

Paolo, see if you can download Celestia 1.5.0. It runs the .cel script with no problems (perhaps a little slow to start, but then it hums along).

This did the trick, thanks. I upgraded to Celestia 1.5.1 and the VMC script worked. At first it didn't occur to me to try an upgrade because the script didn't mention dependence on any specific version of Celestia.


Paolo Amoroso

[Tman]

The VMC public gallery has opened http://www.esa.int/SPECIALS/VMC/SEM3FR0SAKF_mg_1.html

[Stu]

In advance of him joining UMSF I've been asked to pass on greetings and a couple of messages from Thomas Orsmton, who is the "VMC team coordinator from the technical side on the Mars Express Flight Control Team":

"...all of us here on Mars Express have been very impressed with the work being done by members on the forum and we've been downloading and playing with ugordons' colour extraction application too. "

... and...


"...I would be very grateful if you could pass on the message on the forum that all of us on Mars Express are really pleased with what people on the forum are doing and would strongly urge them to send their results to us at vmc@esa.int, with the details at the bottom of this page: http://www.esa.int/SPECIALS/VMC/SEMANKXIPIF_0.html. "

So there you go! Nice to know all of your efforts are appreciated, you Imagemages out there, and keep up the good work!

[ormstont]

Thanks to Stu for passing on the message, I'm registered now and can pass on my thanks to you all once more for the wonderful work you've been doing with our VMC images. I hope that through this forum I can keep in touch with you all as the VMC project continues, with this instrument we're just the tool, you'll be making the discoveries! Especially the users here on Unmanned Spaceflight forum have given one of the warmest welcomes to this new initiative so it's great to be in touch with you directly.

As Stu passed on, I'd really urge you to send in your results to vmc@esa.int - Daniel runs our website at ESOC and we'd love to publish your VMC results along with the routine updates as we get them from the spacecraft. With him looking after the website I look after the camera (as much as I can - my 'day job' is power and comms on the spacecraft) so if you've got any suggestions on what we should do with it that might help us too (although we are heavily limited by operational constraints - with the wonderful results we get from our science instruments the science mission must come first!).

I'm open to questions on the e-mail or here on the forum - if we keep the images coming you can help keep VMC fresh with new processing techniques, image analysis and ideas for the future. VMC is meant to be everyone's camera, I hope that despite our somewhat basic images we can still get some wonderful results.

[imipak]

I'm only an "armchair UMSFer", with no image manipulation skills, but as such I'm delighted to see images flowing from ESA, and I'm equally delighted to see your post. Welcome aboard, ormstont!

[Juramike]

Here is an GIF animation I made from a sequence of MEX VMC images taken on July 31, 2008. (here).

I think it shows a cloud near the terminator under the changing lighting conditions of sunrise:



(Anybody recognize the location? I couldn't figure it out!)

-Mike

[EDIT 9/16/2008 00:04 EDT: OK I think this cloud is over the highlands near Kepler Crater at [-47S, 220W] in Terra Cimmeria]

[Paolo Amoroso]

I'm open to questions on the e-mail or here on the forum - if we keep the images coming you can help keep VMC fresh with new processing techniques, image analysis and ideas for the future.

Speaking of ideas, are there any operational constraints that prevent imaging Phobos or Deimos with VMC?

Thanks to you and the MEX team for the great images and opportunities.


Paolo Amoroso

[ormstont]

Phobos and Deimos would both be fun targets, the biggest problem is the distance between them and the spacecraft (and the relatively low resolution of VMC). Even with our high-altitude pericentre (~10,000 km) we'd have issues imaging Deimos (as it's quite a bit further out). We do come pretty close to Phobos at times but on those opportunities we usually use our primary science instruments to observe (see some results of the recent campaign here: http://www.esa.int/SPECIALS/Mars_Express/SEM5H48N9JF_0.html) and VMC is not allowed to be ON with other instruments. That said I'll keep my eyes out for any encounters where we could try something with VMC.

Maybe someone on the forum would like to do a quick back-of-the-envelope calculation to see at what range we'd start to be able to resolve the moons. This would of course rely on working out the resolution of VMC from Martian features, which again might be a fun job for someone if anyone fancies it!

[chiron]

Hi everybody

I worked the last days on a program for automatic conversion of the VMC images.

The version i provieded on my website at http://www.bernd-leitenberger.de/download/vmc.zip

The Help is missing but will added in the next update.

Whats working is:

- Demosaiking of the bayer mask
- Removing of Hot Pixels

What must be made better is :

- Correction of the color and saturation
- Better debayer Filter (still big differences between near pixels)

I recommend to process the files (multiply can be selected in the open dialog) by it and then use a image processing tool to adjust saturation and to do an unsharp mask.

When someone has more experience with image processing i would be glad if he can provide me with an better debayer algorithm

The program runs under Windows XP , i think also under other Windows version from 98 up.

[tedstryk]

I had a go at the July 29, 2008 dataset. Man, this is some tough stuff to work with!

[ormstont]

Tough stuff to work with indeed makes it all the more impressive when you produce something like that image - it's going up on the wall in the control room for sure! Great work there Ted, I'll ask Daniel to put it on the website as soon as we can (although with Rosetta's Steins flyby next week he's pretty busy!).

Got two observations from last week that we've just downlinked from the spacecraft too, and there should be 4 (I believe) more over the weekend...but I'm taking a brief holiday Monday and Tuesday so they might have to wait til Wednesday I'm afraid! Keep up the good work!

[tedstryk]

Thanks! I am headed out on vacation, but I will try some more images when I get back on Monday.

Ted

[Juramike]

Assembled mosaic from June 22, 2008 series of images (specifically image 3, 6, 9, and 12):



Argyre Planitia above the south pole.
[EDIT 20080916 00:14 EDT: This is an image of Huygens Crater at center[-15S, 305W] above the bright Hellas Basin (lowest point) and the Terra Sabaea is to the right, and the dark zone to the NE of Huygens Crater is Syrtis Major.]

-Mike

[Juramike]

Handy little guide and detailed explanation of the outreach plan for the MEX VMC:

http://esamultimedia.esa.int/multimedia/esoc/Mars_Webcam.pdf

-Mike

[JTN]

http://esamultimedia.esa.int/multimedia/esoc/Mars_Webcam.pdf

"the latency makes this camera the most recent available view of Mars from any spacecraft"

"It is also possible to add files containing the raw pixel values from VMC, as part of the future website developments [...]"

They slew the spacecraft specially for us VMC obs (albeit at times when the other instruments can't observe) -- that seems quite generous!

Note to spacecraft all designers: this non-science type of camera (MEX-VMC) is worth putting on all future space craft.

"The [VMC] design has flown on several ESA missions to date, including Ariane 502, Cluster-II, XMM-Newton and INTEGRAL. VMC cameras are currently also scheduled to fly on the Herschel-Planck ESA astronomy missions."

[Paolo Amoroso]

It would be useful for the VMC site to have an RSS feed for announcing new image releases.


Paolo Amoroso

[ormstont]

Sorry for being a bit quiet - as you can probably see from the ESA website we're going full steam ahead on the blog for the Rosetta Steins flyby tomorrow. Daniel who maintains the VMC website is hoping to get the latest images up soon. In particular you should take a look at the ones from the 29th August - there's something really strange on those pictures. Seems to be large (~100km is my rough calculation) and very bright, casting a dark shadow on the planet and the shadow is detached from the object. Doesn't seem to be anything on the map there so I'm puzzled...ideas on a postcard?!

P.S. Thanks for the idea for the RSS feed - we're definitely thinking of implementing that as soon as we can so you can get reminders of new images available.

[Stu]

re your "mystery object"...

Perhaps...?

[ormstont]

Definitely hoping for Martians (then we'd have something to blame spacecraft anomalies on!) We're hoping to get the images up today...latest probably Monday - sorry to make you all wait!

[ormstont]

Ok...image gallery is online on the website, along with a couple of public submissions from UMSF members (more to come I'm sure!). We've got some more standard image galleries from August and September still to put online but these will come next week after things with Rosetta have calmed down.

Really interested to see what you make of this object!

[djellison]

That is unusual. At first I thought it might be a moon/shadow issue, but that close to the terminator the geometry is totally wrong. It's so close to the terminator, that can't be very tall.

It's a nice challenge - I like it.

[Paolo Amoroso]

In particular you should take a look at the ones from the 29th August - there's something really strange on those pictures. Seems to be large (~100km is my rough calculation) and very bright, casting a dark shadow on the planet and the shadow is detached from the object. Doesn't seem to be anything on the map there so I'm puzzled...ideas on a postcard?!

Any Phobos/Deimos solar eclipses at the time the images were taken? However, the images probably span a time interval a bit too long.


Paolo Amoroso

[Stu]

I may be wrong (probably am) but think this might be the area...



More than prepared to be proved totally wrong!

EDIT: hmmm, looking at other images in the new release batch I'm not so sure. Fun to try tho.

[remcook]

cool, looks like a volcano eruption it's not a cloud?

what's the artifact right above it in Stu's image (near the limb, the rectangle thing...looks like a a line of a few pixel copied several times.)

[ustrax]

I've been far away for so long that I've become a sceptic...

Sorry but to me it looks like an optical illusion...no shadow casted by the apparent object, it looks to me like the shadow is from an elevation on the ground and the supposed "object" is a crater, you can see by going through the images that the shine varies and if you turn a picture 90º you loose that impression of something hovering over Mars...

Hope I'm wrong...

[Stu]

How about a meteoroid impact that sent up a big dust cloud? Unlikely, I know, but wouldn't that be cool?

(This is where someone from MRO, Odyssey or MEx butts in and says "Well, actually, we did see something but we weren't going to say anything yet..." )

EDIT: An "optical illusion"? Okay, where's the REAL Ustrax? What have you done with him?!?!

[ustrax]

I'm here...
This is what I mean:


Looks to me that the brightness of the crater on the right and what I call crater on the left looks, going through the images, the same from one to the other...

But I may be taking too much Canydril...

[Paolo Amoroso]

[...] it looks to me like the shadow is from an elevation on the ground and the supposed "object" is a crater, you can see by going through the images that it's shine varies and if you turn a picture 90º you loose that impression of something hovering over Mars...

Isn't the area too far from the terminator to have such a prominent shadow?


Paolo Amoroso

[ustrax]

In this specific image it looks to me that the shadow is derived from elevations on the terrain to the left and the "object" has fainted in a considerable way.

[ormstont]

Just to put my two cents in, you're right that the "object" fades a lot towards the end of the observation. It could well be that we're seeing something like the face on Mars - just a combination of light and shadow that looks like something we want to see. Nonetheless there aren't any major features I can see on the Mars map that would give rise to such a large flare/shadow. In ustrax's plot the crater identified is (I believe from looking at the Celestia file) Copernicus.

Using Ian Musgrave's Registax techniques he describes here http://astroblogger.blogspot.com/2008/08/w...-over-mars.html, combined with ugordon's colour processing script, I wonder if it's possible to clean up the image and see if we can place it more precisely on a map of Mars. Would be great to see what more it could teach us!

P.S. Top theories so far include trick of the light, cloud or (a long shot, but a cool one) an impact event plume...

[ustrax]

dear Ormstont, I am sorry to be a bit limited in terms of software for the moment but if that carter is indeed Copernicus then, looking at Google Mars, I see a bright patch to the right of the crater (marked) that could be the "culprit"...assuming that I am getting the right orientation and scale...

[ugordan]

It definitely appears to be atmospheric as the shadow moves below it (click to enlarge):


It seems to have dissipated at the end. Based on the rough 100 km size estimate I get a height in excess of 100 km (around 110 km, but the uncertainty is rather large) if my back-of-the-envelope calculation is right using this 3x magnified bit:


If it's an ordinary cloud, what would make it so circular at that altitude and would it dissipate quickly in sunlight? If it's an impact plume, wouldn't we expect a darker color and much lower and more persistent plume?

[Juramike]

Nice animation, Gordan!

As you've shown, the shadow seems much longer in the earliest images, just what you'd expect as the sun peeped up over the horizon.

-Mike

[ustrax]

It definitely appears to be atmospheric

I keep my thought after seing your animation...
the shadow seem to me to be originated on an elevation to the right, as the sun decreases in the horizon the shadow decreases and so does the brightness in the circular feature. I keep my guess: they are not related...

[Paolo Amoroso]

It definitely appears to be atmospheric as the shadow moves below it (click to enlarge):

The movement of the feature suggests that a few hours earlier it was in the night side of Mars beyond the terminator, possibly looking like the bright terminator projections observed telescopically, e.g. the projection seen at Lick Observatory on 5 July 1890 (from Chapter 6 of Sheehan's The Planet Mars).


Paolo Amoroso

[ugordan]

the shadow seem to me to be originated on an elevation to the right

You do realize it would have to be an awfully big topographic high, don't you? We're talking about objects 100 km in size and the shadow is something like twice that size, even well past the terminator. That would put Olympus Mons to shame, no?

Furthermore, the shadow isn't simply getting shorter, it's actually disappearing at the same time the bright circular object (let's call it 'cloud' for discussion's sake ) is disappearing.

[TheChemist]

You do realize it would have to be an awfully big topographic high, don't you? We're talking about objects 100 km in size and the shadow is something like twice that size, even well past the terminator. That would put Olympus Mons to shame, no?

The typical anti-Ustrax that posts lately here. Now he sees an inverse abyss

[ustrax]

The typical anti-Ustrax that posts lately here. Now he sees an inverse abyss

Now you got me in my new strategy...to assume there's nothing special in order to be surprised in the end of it all...

I DON'T want Oppy headed towards Ithaca!
(See what I mean?... )

You do realize it would have to be an awfully big topographic high, don't you?

No I don't...

[ugordan]

Now you got me in my new strategy...to assume there's nothing special in order to be surprised in the end of it all...

Congratulations and welcome to the club known as The Pessimist. I hope you'll enjoy your stay!

[ustrax]

Congratulations and welcome to the club known as The Pessimist. I hope you'll enjoy your stay!

Thanks but I believe it won't be long enough to be enjoyed in its full splendor...

[siravan]

Based on the rough 100 km size estimate I get a height in excess of 100 km (around 110 km, but the uncertainty is rather large) if my back-of-the-envelope calculation is right using this 3x magnified bit:

How do you calculate the height? My back-of-envelop calculation based on the ratio and of the shadow to the object size and its distance from the object is more consistent with an altitude half the object size (50 km if the diameter is 100 km).

[ugordan]

Yep, it appears I messed up the calculation of (at least) illumination incidence angle using the shadow shape, I did an inverse tangent of a/b instead of inverse cosine of b/a. That, by itself, lowers the end result to some 80-ish km, which might still be wrong. 110 km was no doubt suspicious, being at upper fringes of the atmosphere.

[Paolo Amoroso]

The movement of the feature suggests that a few hours earlier it was in the night side of Mars beyond the terminator, possibly looking like the bright terminator projections observed telescopically, e.g. the projection seen at Lick Observatory on 5 July 1890 (from Chapter 6 of Sheehan's The Planet Mars).

The date and time on the drawing can be read clearly only on the printed edition of the book: "1890, July 6d 9h 25m P.S.T."


Paolo Amoroso

[ugordan]

Here's a new version of VMC2RGB, this time implementing the adaptive Homogeneity-Directed interpolation, snatched from dcraw (algorithm was based on the work of Keigo Hirakawa, Thomas Parks, and Paul Lee) as slinted suggested earlier. It's not a groundbreaking improvement and your mileage may vary, but if you take care of how you process the images wou might end up with slightly sharper images. See below for 2x enlarged inset comparing the old and new algorithm, with identical processing in Photoshop:



The target image in question was greatly boosted in saturation and sharpened so it's pretty noisy, but shows more details:


Download it here:  vmc2rgb_v02b.zip ( 40.37K ) Number of downloads: 876


EDIT: I discovered a bug when using the new algorithm that clips some saturated pixels to zero, it's now fixed.

[stevesliva]

Does fog cast a shadow? Would it be forming above an ice-filled crater in the southern hemisphere?

Or perhaps a leeward cloud that dissipates in the sunlight?

[ormstont]

Ok...more info on our strange cloud...we've got a lot of the Mars Express scientists at ESOC today for planning meetings and I showed the images to our OMEGA team who are the MEX cloud experts! They've only had a quick chance to look so far but they were very excited, hopefully I can chat with them again later in the day. They also said that if the altitude was indeed 80km (I credited you all with doing the analysis for us...and they loved the animations!) then the feature is almost certainly an ice cloud. I'll keep you all posted on any more info I get!

[remcook]

yes, I think 80 km is a normal altitude for these mesospheric clouds, but I think these are normally not that bright, especially when looking down on it.
For instance, the CO2 clouds reported here are not visible:
http://www.esa.int/esaCP/SEMC4JZ7QQE_index_0.html
What latitude is this roughly? Apparently, mesospheric clouds are common around the equator:
http://www.agu.org/pubs/crossref/2007/2006JE002805.shtml
This article came up here before and shows similar clouds+shadows:
http://www.esa.int/esaCP/SEM1DV3MDAF_index_0.html

[ormstont]

Wow...you beat me to posting the link I've just been chatting again with the Omega team (the ones that wrote that paper that your last link is based on)...if anyone knows Mars clouds it's them! We had a quick look at surrounding features and worked out the VMC cloud would be around 18 degrees South and 162 degrees East, which would put it close to the equator but still away from a common region of these clouds (based on Omega observations).

More generally all the MEX instrument science teams responded very warmly to the results produced by yourselves and other VMC contributors and may even see about giving us more VMC observations as a valuable contribution to Mars Express science. We'll put it all up on the VMC website though as always, as soon as it's down on the ground (next dump should be Friday/Saturday, so look for more new pics at the start of next week!).

[elakdawalla]

I'd like to include one of the VMC crescent images in my "Year in Pictures" roundup for The Planetary Report but am so far not happy with what I have been able to produce. Attached is the result of my fiddling with the crescent image from the "Best of 2007" feature. But I need an image from 2008 for this roundup. There are a lot of crescent shots in the archives from the spring and summer of 2008, though most of them appear to be saturated. I'm going to keep fiddling with the data -- these images are really fun -- but I know there are lots of people here who are better than I am at making pretty Mars color images and am hoping that one of you will be able to come up with something more spectacular than I can.

--Emily

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[ugordan]

All 2008 crescents indeed appear to be severely overexposed. The closest thing to a non-overexposed crescent view are images from June and July, but they're already at a fairly fat phase. Here's one of the later ones:

It's looking down on the southern hemisphere with a high cloud peeking over the terminator.

If you're willing to put up with overexposed high phase shots and have an image that doesn't really scream "this is Mars", might I suggest one from that sequence showing clouds at the terminator that was brought up here, from Feb 14th.
FWIW, either Mars isn't terribly reddish at those high phase angles or the VMC data is very noisy, or both. Getting anything out of those thin crescents except a greenish hue seems like an exercise in futility.

[ormstont]

So, looks like our other MEX instrument teams are working hard to find out more about our strange cloud - looks like we could be in for more too - they said that this is the season we'd be expecting these clouds on Mars (although the VMC cloud is larger and more pronounced than anything seen before!). Will keep you posted when I hear more!

For the crescent images - sorry that they're all really saturated - those problems were one of the reasons I've moved to doing the 4 exposure step cycle (even though it cuts down the number per observation of properly exposed images) you see on the current images. The nice thing about the saturated images are that we see the features in the night side, over the terminator (I know...excuses, excuses!!). I promise to try harder at the next crescent season! Of course - any suggestions on how best to set the exposures or timing of images let me know - you're the operators of this camera!

[ugordan]

I'd be interested in knowing what the difficulties are in adjusting exposure for a given observation. Is it the uncertainty of how bright Mars will be at certain phase angles?

While we're at the subject of exposures, knowing how long each raw image was exposed would be of additional help in processing.

An unrelated observation - it seems to me that if only we had a flatfield frame for the VMC we'd be able to get much better images out of it. A lot of the noise seems static on the detector.

[ormstont]

Well, part of the difficulty is that we have no way of predicting how bright Mars will be in a given location at a given phase angle. I'm sure one exists but our aim is always to allow the public to guide VMC activities - as I say, you are the operators of this instrument. If anyone comes up with a way of predicting it then I'd be more than happy to implement it!! I implemented the 4 step exposure setting as a workaround for this - guaranteeing whatever the observation we should get some well-exposed shots.

That's a good point about knowing the exposure settings - I'll see how we can work that into the routine flow of information and processing of each image. For a guideline though, the first image of every observation is always 14ms. For the rest of the observations I'd have to look for you on Monday at work, will do that and get back to you then.

For the flat field - I'm vaguely aware of what the term means - would it be a long exposure image with the spacecraft pointed at space? If you let me know roughly what I need to command MEX/VMC to do then I'll try and schedule a slot when we can do it. I know I use this as a mantra...but it's everyone's instrument, you let us know what to do!

[ugordan]

would it be a long exposure image with the spacecraft pointed at space?

That would be a dark frame, used for figuring out how the background signal increases with exposure (varies with temperature, hot pixels, etc). Part of wanting the exposure setting comes from the desire to have a rough model for dark background - two separate exposure images of a same target will produce different colors for different amounts of background signal. For example, a short exposure with VMS typically shifts overall colors towards blue as the background (grayish) overwhelms the Mars signal.

A flat-field is usually produced by imaging a sufficiently bland target so any noise in the image is variations in pixel sensitivity, crud in the optics, vignetting etc. This can be divided out from subsequent images to provide better S/N ratio. I don't expect we can get a look at a bland target now that we're at Mars, that sort of thing could have been done back on Earth, but then again this is not a scientific camera so most likely wasn't "calibrated" this way.

[Tman]

A flat-field is usually produced by imaging a sufficiently bland target so any noise in the image is variations in pixel sensitivity, crud in the optics, vignetting etc. This can be divided out from subsequent images to provide better S/N ratio.

For example, the Mars Rover's lenses have also a couple of "noises" by now, beside their vignetting.
This image shows clouds on sol 1647 and this image from sol 1645 only the dirt on the lens. As a "fieldwork" flatfield you can use the inverted sol 1645 image for some clearing.

[Paolo Amoroso]

I don't expect we can get a look at a bland target now that we're at Mars, that sort of thing could have been done back on Earth, but then again this is not a scientific camera so most likely wasn't "calibrated" this way.

Would this Iris technique for extracting a flat field from science images, or something similar, be useful with VMC images?


Paolo Amoroso

[ormstont]

Ok, get what you're going for there - the only suggestion I could possibly make for an in-flight test would be an exposure of Mars at low altitude that's long enough to blur out any surface detail (although I guess that would probably saturate the detector too).

I'll see at work tomorrow if any tests were made pre-launch although I think most of the dirt/objects/scratches(?) we see on the optics came after Beagle 2 ejection. VMC is right underneath the Beagle ejection mechanism so there might have been outgassing or debris from the pyro bolt firings that separated Beagle (some small objects can be seen moving away from the spacecraft in the Beagle separation images).

Based on this possibly the technique that Paolo mentions with this software could be helpful? Would certainly be great if we could extract the artefacts from each image.

Finally, you mention what we really need is a flat-field. Would a dark frame be helpful too? I've never tried VMC pointed away from Mars, so would be interested to see what happens (more out of engineering curiousity)!

[ugordan]

I don't personally think a dark frame would be all too useful for purposes of processing images alone - the detector is 8 bit and the majority of the noise is flatfield related noise. That said, I wonder how long an exposure can you get wih the VMC? It's a wide angle imager so we can forget about imaging individual stars probably, I wonder if it'd be possible to capture the Milky Way glow at least? It would probably depend on how fast dark current builds up with exposure.

[jekbradbury]

I am trying to organize the images by position in the orbit, but the quoted orbital period(s) on the Mars Express website (there are two different numbers on different parts of the site) don't seem to match the images. Taking the time since the beginning of 2008 modulo the orbital period of 24180 seconds should put the partial disc images near each other, but doesn't. What is the actual orbital period? Alternatively, would the SPICE kernels have this data?

[ormstont]

That said, I wonder how long an exposure can you get wih the VMC?

Ok....first off - the VMC exposure range is pretty wide. There are two exposure ranges supported -

• 0.4 ms to 191.6 ms in increments of 0.8 ms
• 200 ms to 95800 ms in increments of 400 ms

The widest range tested was in our first two observations in 2007, the first where we almost missed the planet here: 2007-01-28 Observation, and the second where we got our first disc image here: 2007-02-26 Observation. I'll look up the exposure ranges used here for you, but I know we only just touched the longer range.

For a long exposure test pointed at deep space I might see what I can schedule as I'd be interested to see how VMC performs in those conditions too, I'll keep you posted on my progress.

I am trying to organize the images by position in the orbit

Not sure exactly what you're trying to do here, but please let me know a bit more and I'll see how we can help. If you mean what point in the orbit, almost all VMC observations were taken just after apocentre. If you mean ground location it's a bit more tricky as the MEX orbit precesses in Argument of Periapsis to allow our pericentre to not only be over different longitudes but also different latitudes (although longitude obviously varies rapidly with Mars spinning, the latitude precession is much slower, over the course of a year).

What is the actual orbital period? Alternatively, would the SPICE kernels have this data?

Ok...the MEX orbital period has changed throughout the mission. SPICE kernels will give you a full, complete and accurate definition of the MEX orbit, but there are some shortcuts you can take. If you go to the MEX SPICE server here: ftp://ssols01.esac.esa.int/pub/data/SPICE/MEX/kernels/ and go into the orbnum directory you'll find a .ORB file that lists all the MEX orbits. The column OP-Event UTC APO gives the apocentre time for each orbit - so the period is the duration between any two adjacent values in this column. For even more detail on the MEX orbit you can use the EVTM_ files at the auxilliary data server here: ftp://ssols01.esac.esa.int/pub/data/ESOC/MEX/ (Just take the highest version number file for the latest).

[jekbradbury]

That was exactly what I was looking for. Taking into account the actual average period for the time period of these images, they are correctly placed in the orbit. I had hoped there would be some pictures at every point in the orbit, but it seems the images are in two sections: a ~1hr period near apocenter, and another ~1hr period near pericenter. My goal was a simple animation of what VMC sees on a typical orbit, not taking into account phase or ground location, just trying to show the varying size and brightness of the disk. I'm assuming operations (downlink etc.) and other instruments prevent this from being done, but one VMC image every ~5 minutes for one full orbit would make for one amazing animation.

[Juramike]

I finally downloaded Celestia (slaps head, why did I wait so long?) and poked around Mars on the date of the observation time to line up the features (thanks for the suggestion, Gordan!).

The location of the cloud feature in post 14, this thread was identified (highlands around Kepler Crater [-47S, 220W])
and the caption/location of the mosaic in this post was identified and corrected.

Color me embarrassed.

-Mike

[EDIT: Oh great. This post is right at the top of the page...terrific...]

[Juramike]

Interesting how both the "mystery cloud" picture and the putative dawn cloud (post 35) are both located around the highlands of Terra Cimmeria.

Is this a known cloud zone?

-Mike

[ormstont]

...it seems the images are in two sections: a ~1hr period near apocenter, and another ~1hr period near pericenter....I'm assuming operations (downlink etc.) and other instruments prevent this from being done

Yep, you're right there - it's mainly instrument operations that constrain us to those windows. Aspera, a Swedish experiment looking into space plasma and energetic atoms aims to be on permanently to get a good dataset. However, every 3-4 orbits (~once per day) we have to perform a reaction wheel offloading and orbit maintenance, which means firing the thrusters. When we do this Aspera shuts down for an hour because the thruster plumes would interfere with their measurements. This thruster activity is always placed right after apocentre for maximum activity and that gives us our ~1 hour VMC window. Sometimes though these are impacted as you say by ground station passes a that's why we get our average frequency of 2-3 obs per week.

The VMC obs just after pericentre are much rarer and happen when we perform a orbit change, here we have to fire the thrusters to achieve this but the point of highest efficiency is at pericentre. Therefore Aspera shuts down and we get a relatively low-altitude VMC observation (assuming Flight Dynamics don't choose that period to obtain tracking data from the burn).

one VMC image every ~5 minutes for one full orbit would make for one amazing animation.

You're very very right here too (you could come work for us!), we'd all love to do a full orbit animation! As this would require agreement from all the other instruments though it will require quite some negotiation. I'm constantly on the look-out for chances though, but don't want to impact our prime science mission. The other slight problem is that the VMC packet store (like a directory on a computer) is limited to 60 images, so we'd have to ask nicely for another instrument to lend us their packet store

Color me embarrassed.

Lol....we all get embarrassed - how do you think we felt when we got our first VMC images and they looked like this: http://www.esa.int/SPECIALS/VMC/SEM4SJEVL2F_1.html#subhead4 ?! At least it makes for a cute story in the history of VMC I'll ask Daniel to update the captions for your images on the website. Even if they're of a slightly different location they're still great work!

[Juramike]

It's baaaack!

Another cloud sequence at sunrise over Terra Cimmeria taken one month after the post 35 cloud movie. This shows a much more impressive series of clouds. These are located near Electris Crater [-45S, 150W] in Terra Cimmeria.



(click to animate GIF)

The brightish crater at center is Copernicus crater at [-50S, 170W]. There was another dimmer cloud visible near the terminator just to the ESE of Copernicus crater but it wasn't as photogenic (or on all the frames).


All these used the first image (the most exposed) in the sequence of 4 exposures. These are beautifully spaced in 10 minutes steps for a neat time-lapse sequence of 1 h.

Terra Cimmeria seems to be a breeding ground for these clouds (3 for 3!). Might be nice for the next scheduled observation run that views Terra Cimmeria near the terminator to use the longer exposure times, and space the images at shorter time periods (3 to 5 min.). Then you can get a neat smooth movie, or do image stacking to pull up the contrast on a particularly nice set.

-Mike

[ormstont]

Interesting that we might have a cloud factory on our hands! I'll ask around and see if anyone here has any ideas why there should be clouds generated around this region. The instrument team did indicate to me though that we're going into a "cloud rich" season at the moment, so maybe it's just coincidental that most of our terminator shots recently have been around this region?

Also...I promised to update you on the exposure settings used. I'm still trying to work out a way to pass exposure information on every image through our automated processing chain. However, all recent images have used the 4-step exposure settings, with looping values of 0.4 ms, 6.8 ms, 14 ms and 22.8 ms.

For changing the exposure settings to better catch clouds - this is very possible, I'll try and have a look at what we can do and when we can do it - maybe come back to you and ask you to define your very own VMC observation

[ormstont]

Just a quick plug - got some more lovely shots from last week of the volcanoes...just gone up on the VMC website

[Juramike]

The thing that's been puzzling me is the appearance of the middle "rolling" cloud in the the sequence above. From the orientation of the image (S is roughly at top), it appears that the cloud stuff is moving/growing from S to N.

I would have thought that if there is a global redistribution caused by the CO2 freezeout at the cold high South Pole during the S hemisphere winter, then the overall circulation pattern (especially near the S pole) should go from N to S. This is in direct contrast to the image sequence.

This could be a parallax effect due to changing viewing angle, making the clouds way the heck up there. Or the "rolling" impression could be due to the cloud actually growing N towards the daylight due to the sun starting to warm and mix the upper layers of the atmosphere. (Kinda like the morning clouds you see here on Earth, just on a bigger scale).

I'm going to see if I can add the shorter exposure images (which I guess must be the 14 ms images) into the sequence to make a better resolution movie.

-Mike

[djellison]

I love this camera.

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[Juramike]

Here is an attempted mosaic of the "relatively clear and kinda undistorted parts" of the MEX VMC images covering August 4-September 11, 2008.
(It's still a work in progress - mosaic is too strong a word, I was overlaying these images on the USGS Mars Map - it's more analogous to what the psycho killer guy was doing in "The Silence of the Lambs")



Here is an EXCEL table I made that lists the image date, approximate time, and the most distinctive feature nearest the center of the image for those MEX VMC images. This will hopefully cut down on the frustration of trying to figure out the features on the image:  MEX_VMC_Features_list_20080918__August_4___September_11_2008_.xls ( 19.5K ) Number of downloads: 692


-Mike

[Juramike]

There are few guarantees in life...
but finding clouds in morning light near [-45S, 193W] on Mars in one of them.

More MEX VMC images from July 6, 2008 and July 12, 2008 (impressive display) of sunrise clouds:



Both images lightly processed, the July 6 image came from the jpeg from the MEX VMC website, and the July 12, image was downloaded in RAW form, debayered through Gordan's latest tool, then pushed to grayscale, then contrast curve modified, and exposure modified. (All images rotated to fit the July 31st and Aug 31st orientation.)

This shows the identification of nearby craters:



-Mike

(For those of y'all keeping score: this is 4 sets of clouds out of 4 MEX VMC observations at this location.)