MEX VMC - Back on, and online! Options

[ormstont]

Hi all!

Thanks once more to Mike for his great work on the 19th March images, please do leave a comment on the VMC blog to show your appreciation! I'll hopefully get a chance to add some of the bits he's posted here too (if that's ok Mike?).

Thanks too for the troubleshooting of the Celestia script. It seems to be a problem with how the scripts are processed by the blog software (they're fine before upload). I'll try and get to the bottom of what's happening and get it fixed as soon as I can. I know the scripts are quite verbose but I wanted to make it as accessible and easy to use as possible for those that might not be familiar with VMC observations or with Celestia. As always though, any suggestions are very welcome!

Last thing...you'll notice there are some new images now from 19th March, and the 20th March (they were waiting on board for a dump opportunity). There's still some data from the 20th March left on board, that should come along with a new observation on Saturday. Next Thursday though we've got an observation with a dump same day - those images (assuming all goes well) should be online right after...hot off the spacecraft

P.S. Haven't shown the images to our Venus Express colleagues yet...let's see if we can make them jealous..promise I didn't steal them from their VMC!

[Juramike]

(if that's ok Mike?).

Absolutely! Let me know by PM or e-mail if there's anything I can do to pretty them up!

-Mike

[Juramike]

April 9 image enhancement of what I think might be Alba Mons.
(Celestia pointing information was kinda strange - according to Celestia, Mars should've been gibbous)


To make the image, I stacked 3 images (09-099_05.09.13_VMC_Img_No_15.png, 09-099_05.05.40_VMC_Img_No_11.png, and 09-099_04.58.33_VMC_Img_No_3.png). No. 15 was the base image, and a fuzzy layer mask was made for the interior section of the crescent. The images were then averaged to help get a better S/N. (No. 11 opacity 50%, No. 3 opacity 33%). Then the combined region around Alba Mons was selected and a white to black gradient was created. This gradient was subtracted from the region around Alba Mons using the Apply Image function. This section was then contrast enhanced, and a mask used to add this to the original combination. [This is the technique I've been using for the Titan images]. An Unsharp Mask was done, and finally, the whole thing was contrast-enhanced with a Curve.

Here's a comparison of a contrast-enhanced crop of Image No. 15 compared with the result from the recipe described above:


(Spacecraft motion and the changing of the perspective made the borders of Alba Mons fuzzier but better S/N. The layer mask set from Image 15 kept the crescent image crisp.).

-Mike

[Juramike]

[Alternatively, I guess that dark spot above could also be Arum Chaos]

The image was taken April 9, 2009 05:02:06 UTC.

Any guesses?

[Juramike]

The May 2009 MEX VMC images are all nicely taken at about the same distance (thus have the same size) and all appear centered close to the N Pole (based on cloud banding). The crescents are all oriented similarly also.

Here is an EXCEL table of the MEX VMC image crescent midpoint longitdudes for the May images:

 Orientation_of_MEX_VMC_images_May_2009.xls ( 18.5K ) Number of downloads: 637


(I was using this to see if I could pull off a multi-day movie of clouds centered on the same location. No luck!)

[Juramike]

Here is a rotation sequence study of the May 27-May 30 MEX VMC images sequenced according to shifting westward longitude of the crescent midpoint.


(click to animate)
(Mars appears rotating underneath, the images are NOT in time sequence)

The first image in the sequence shows how Alba Mons really makes cool clouds. Olympus Mons is the dark circle spot, Alba Mons is to the upper right, the extra-bright clouds are to the NE of Alba Mons. (Right near the lens artifact )

[Fran Ontanaya]

A cool one from a couple weeks ago:

http://webservices.esa.int/blog/post/6/774

[Juramike]

MEX VMC image of a possible cloud or bright albedo feature near Hesperia Planum taken on August 15th, 2009:
Manually blended set of four differently exposed images then contrast enhanced.



(Full resolution processed image here: http://www.flickr.com/photos/31678681@N07/3867648999/)

[Juramike]

The July 11 2009 MEX VMC image shows the cloud near Arsia Mons is still present (far left near the terminator).

Here is a composite:

[Juramike]

Latest images show a large cloud complex and a cuter bunch of clouds to the (S?):

http://webservices.esa.int/blog/resource/6/8360

I'm wildly guessing the large complex is near Acidalia Planitia. Hard to tell with few surface features.

[Juramike]

I tried to pull of a "super-resolution" image from MEX-VMC images taken on July 11.

I thought that two images from slightly different perspective might be able to generate subpixel resolution. Turns out that the 3 minutes between shots with similar exposure levels is still enough to radically change the perspective, making it not worth the effort. S/N got helped a little bit, tho...

Results here: http://www.flickr.com/photos/31678681@N07/3942553995/

(Link to "super-resolution" technique: http://www.lpi.usra.edu/meetings/LPSC98/pdf/1817.pdf)

[I credit Ted Stryk's blog for pointing me in the correct direction for this image technique.]

[elakdawalla]

There's something weird in these photos that's not visible in photos from days before or after -- what I assume are high-altitude clouds beyond the terminator; and is that a pile of clouds above the pole?

Attached thumbnail(s)

 

[ormstont]

We're certainly seeing some interesting cloud dynamics during this "crescent season" on VMC...as always you are our scientists and investigators on VMC so if you want to submit any analysis or favourites please e-mail us and we can add it to the site!

I also wanted to flag that we've got some great observations that just took place and some more coming up. First off...for the next few months the time between image capture and dump to earth (which triggers the website upload) will be reduced by a lot. Some images have gone online within a couple of hours of being dumped!

We've also got some lower altitude images, such as these two observations:

http://webservices.esa.int/blog/post/6/912
http://webservices.esa.int/blog/post/6/913

These are showing some really nice surface detail, and are being captured with a tightened exposure range and less time in between images. There should be some more coming up soon, including one looking at the limb for cloud activity (although I think you can already begin to see limb clouds in the galleries above).

Finally, an apology and an update on the Celestia positioning scripts on the website - these were being based on an old planning reference which is why they were sometimes not matching well with the actual observation. This has been updated now and all recent and coming observations should be correct. I'll try and systematically update the old observations but if there are any particular ones you need do let me know.

So should be a fun Christmas for VMC, as always I look forward to your discussions, comments and results!

[elakdawalla]

Thanks, ormstont!

For those of you who've been doing work on the VMC images, have you developed any specific workflow for boosting the Mars-like color in these images? Is it just as simple as increasing the saturation or do you do any channel-specific processing?

--Emily

[elakdawalla]

I've been fiddling a bit with this problem. I don't think I've found the best solution yet, but here's a few tries -- I'd welcome opinions, as although I've done a lot of work accessing raw images, I haven't spent much time trying to get colors to look right and I feel sort of as if I'm wading into deep water here.

Version 1: Just fiddled with levels to try to make a bright spot turn a Mars-like orange.


Version 2: Jacked up saturation, then levels.


Version 3: Channel mixing: red = red minus 50% blue, blue = blue minus 50% red, green stet, luminosity constant.


Version 4: Channel mixing: red = red minus 50% blue minus 20% green, blue = blue minus 50% red minus 20% green, green stet, luminosity constant.


Not sure what to try next...any suggestions?

--Emily