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HRSCview, New online HRSC image viewer
elakdawalla
post Mar 19 2007, 08:50 PM
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I just received this press release and didn't see it on ESA's website so thought I'd post it in full here. But first, here's the URL for the new HRSC image viewer:

http://www.geoinf.fu-berlin.de/hrscviewweb/

Have fun, guys!

--Emily
QUOTE
NEW ACCESS AND VISUALISATION FACILITY
FOR MARS EXPRESS HRSC IMAGES

Press Release: March 19, 2007
Issued By: Gerhard Neukum, HRSC Principal Investigator

The High Resolution Stereo Camera (HRSC) is one of the outstanding experiments on the ESA Mars Express Mission (MEX) (cf. Neukum et al., 2004, ESA SP-1240). MEX has been in orbit about Mars from January 2004. The mission has just been extended until May 2009. By now, the HRSC has covered close to 35% of the surface of Mars in stereo and color at a resolution of between 10 and 20 m/pixel. Much more of Mars has been covered at lesser resolution.

All data are and will be available in preprocessed form up to level 3 through the ESA Planetary Science Archive (PSA) and in parallel through the NASA Planetary Data System. So far, digital terrain models, although produced for the needs of the HRSC Co-Investigator Team from the stereo data, have not been archived with ESA or NASA and have only in exceptional cases been made available to the community at large outside the HRSC Team proper. The reason for that is that the DTMs produced so far are of non-certified, non-archivable quality.

We have received word from the community that generally better and faster access to the data would be appreciated and DTMs as the main asset of the HRSC experiment would be required for scientific needs and mission planning. Therefore, we are undertaking - with substantial support from our national space agency (DLR-Bonn) - the task of reprocessing all data for the derivation of high-resolution certified DTMs that will eventually be archived with ESA and NASA depending on successful negotiations and agreements.

The hi-res DTM production is being done in cooperation between my group at the FU and the Experiment Team under the leadership of Ralf Jaumann at DLR. Also, the need for faster access by the community at large for quick screening of the HRSC image data and some instant manipulation for a rough overview of the assets of the data through computer-based means before going to the ESA or NASA archives for substantial downloading efforts has been expressed to us. The solution we have come to is to establish the following:

HRSCview: Online visualisation of the Mars Express HRSC dataset

A website that provides the ability to explore within the nearly 2 TB of HRSC images is opened for public access thorough a joint website of the Freie Universitaet Berlin and the German Aerospace Center (DLR) at:

http://www.geoinf.fu-berlin.de/hrscviewweb/

HRSCview permits exploration within the images by carrying out on-the-fly data-subsetting, sub-sampling, stretching and compositing, and in the case of perspective views, projection. This means regions of interest can be explored at full resolution without needing to download full data-product sets.

It is possible to view colour and elevation composites with nadir images and select different colour stretches or infra-red channel substitution. It offers perspective views with a choice of viewpoint and exaggeration. The data are explored using Mars surface coordinates, making it simple to move between multiple images of the same location, between adjacent images, and also from a global image-footprint map directly into an HRSC image at a position of interest. The pixel scale of the view can be selected; distance and elevation scale bars are provided.

Images can be accessed by orbit/image number as well as via the footprint map. In either case, a link is provided to a data-product page, where header items describing the full map-projected science data-product are displayed, and a direct link to the archived data-products on the ESA Planetary Science Archive (PSA) is provided.

In general, the elevation composites are derived from the HRSC Preliminary 200m DTMs generated at the German Aerospace Center (DLR), which will not be available as separately downloadable data-products. These DTMs are to be progressively superseded by systematically generated higher resolution archival DTMs, also from DLR, which will be made available for download through the PSA, and be similarly accessible via HRSCview. A number of images which have already been processed in this way are immediately available for visualisation or download via HRSCview.

HRSCview differs from the service provided by the PSA in that it provides a means to explore within the individual (but very large) images, carrying out a preliminary on-the-fly processing of the science data.

HRSCview features:

* nadir, colour composite, elevation composite browsing
* footprint map, with direct navigation into images
* location selection by surface coordinates or orbit number
* perspective views
* direct switching between overlapping images at point of interest
* click off-the-edge of one image to move directly into adjacent coverage
* links to full level-2 and level-3 data-products from product description page
* links to high-resolution level-4 data-products for several images where archive-quality DTMs have been generated
* alternate archive-DTM footprint map

Comments, questions, or suggestions are very welcome, and should be directed to Greg Michael (gregory.michael at fu-berlin.de) and the HRSC Science Coordinator, Stephan van Gasselt (vgasselt at zedat.fu-berlin.de). A poster on the system was presented at the LPSC meeting last week in Houston and will be presented at the EGU conference in Vienna.


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djellison
post Mar 19 2007, 09:52 PM
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I think we need a code monkey to get to work on the DT4 elevation format and the remaining Level 4 products.

http://www.geoinf.fu-berlin.de/cgi-bin/ion...image=2039_0000

The moment someone can get them converting into some sort of common 3d format....we'll be away.. 720p Anims-a-go-go. The attached is from the Level 3's. It's not really documented so far, but I assume L2 is the radiometric, L3 the map projected and L4 the very juicy elevation and then one presumes the image channels have been projected to fit the elevation model ( as they don't overlay because of the perspective of each channel )

Doug
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dilo
post Mar 19 2007, 10:24 PM
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Thanks Emily for this link! smile.gif
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CosmicRocker
post Mar 20 2007, 03:55 AM
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I just came to post the same email, and am glad to see you folks are already on top of it. What you are already pulling up is pretty impressive. You're way ahead of me. smile.gif


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slinted
post Mar 21 2007, 12:27 AM
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This is a very useful tool indeed! It has great linkage between the overview maps and the actual HRSC image products. Also, to our benefit here, you can directly link to an image+position+zoom.

Here's a couple images of the Columbia Hills almost 2 (earth) years apart, showing the effect of changing wind direction on the dark dust devil streaks.

2004-01-16

2005-10-20
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elakdawalla
post Mar 21 2007, 01:34 AM
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Wow, slinted, great find! ohmy.gif ohmy.gif

For those of you who've been following closer than I -- does this change in streak direction happen every Mars year?

--Emily


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mhoward
post Mar 21 2007, 02:34 AM
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QUOTE (elakdawalla @ Mar 21 2007, 01:34 AM) *
does this change in streak direction happen every Mars year?


Is it a real change or a lighting difference? If it can't be a lighting difference, it seems like a pretty amazing change.
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slinted
post Mar 21 2007, 07:37 AM
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With such a dramatic change, lighting differences seem a likely culprit, but I think we are seeing actual surface changes. Here are two images from THEMIS showing similar change in streak direction:

2003-09-26
2005-10-08 (12 days before the second HRSC image linked in my previous post)

I am having a hard time finding the answer to your question Emily. In an early press release about Spirit's dust devils, there was a mention of 2 dominant directions: southwest-to-northeast in early spiring, northwest-to-southeast in summer, but that doesn't explain the streaks seen in the later images since the neither of these directions align with them.

There is an abstract from LPSC 2006 that makes reference to the 'new' wind direction ("...many dust-devil tracks in previous MOC imagery have been erased, replaced with NNW-trending wind streaks indicating winds from SSE"), but does not say if it is a regular, annual shift.

edit: I should qualify the streaks as being wind streaks, and not necessarily dust devil tracks. The features seen in the 10/05 images are so broad that it's not clear that dust devils are directly responsible. For a better understanding of the processes involved, see Greeley's Martian variable features: New insight from the Mars Express Orbiter and the Mars Exploration Rover Spirit which includes an analysis of the 2004-01-16 HRSC image.
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slinted
post Mar 22 2007, 01:41 PM
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After a little more hunting, I found two wide angle MOC images that show exactly when the newer N-S streaks were formed. S04-00238 was taken on March 5th, 2005 and S04-00558 was taken on March 12th, 2005. The difference between the two images is dramatic given the short amount of time between them but what is even more shocking with regards to Spirit are the equivalent sols: 416 - 423. Much to my surprise, the formation of these N-S streaks corresponds to Spirit's first and most significant cleaning event, as well as the first dust devil sighting! blink.gif

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ustrax
post Mar 22 2007, 02:04 PM
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QUOTE (slinted @ Mar 22 2007, 01:41 PM) *
The difference between the two images is dramatic given the short amount of time between them but what is even more shocking with regards to Spirit are the equivalent sols: 416 - 423. Much to my surprise, the formation of these N-S streaks corresponds to Spirit's first and most significant cleaning event, as well as the first dust devil sighting! blink.gif


slinted...you have made a GREAT work!!! blink.gif


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MarsIsImportant
post Mar 22 2007, 02:57 PM
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Wow!

It's pretty clear in my mind that these are real surface changes. Lighting differences don't account for all the changes.
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CosmicRocker
post Mar 23 2007, 05:49 AM
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Whoa! I don't think I fully appreciated the implications of your discovery when I first scanned this thread, slinted. I can't imagine that this is an effect of different lighting conditions. This must be a local, but quite large event that occurred some time within a 7 day window. The apparent correlations to the cleaning event and the first DD of the season really makes one pause to consider. Great work!


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CosmicRocker
post Mar 24 2007, 05:36 AM
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Emily: That was a very nicely done blog entry on this topic today. I'm surprised this hasn't generated more discussion here. I think Dan's detective work is one of the best examples of I've seen of a space "enthusiast" making a significant scientific observation with publiclly available data.


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SteveM
post Mar 24 2007, 05:56 PM
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QUOTE (slinted @ Mar 22 2007, 08:41 AM) *
After a little more hunting, I found two wide angle MOC images that show exactly when the newer N-S streaks were formed. S04-00238 was taken on March 5th, 2005 and S04-00558 was taken on March 12th, 2005.


What surprised me is that when I checked the individual images, rather than the blink, the dark streak was in the later image, but there was a faint dark streak in the same place in the earlier image. Are we looking at the cleaning off of a light dust cover or is this the deposit of a second streak in the same place?

The second point is that the dark streak (or streaks if this is a generation of a new one rather than cleaning of an old one) begins at a crater. I seem to recall that many of the dust devil tracks in the early satellite images of Gusev began at craters and, of course, we've seen the streaks downwind of Victoria.

Can anyone hazard an informed guess of what's going on here?

Steve

This post has been edited by Steve: Mar 24 2007, 05:57 PM
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elakdawalla
post Mar 24 2007, 06:29 PM
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My very basic understanding is that the dark stuff isn't "deposits," it's just areas of disturbed soil. That's why rover track marks start out dark too. Wind streks tend to start at crater rims because regional winds blowing over bits of topography generate turbulence that can kick up dust (and apparently, sometimes, dust devils). It wouldn't be a huge surprise to me to see some paleo-indication of a wind streak in the same area -- all you need is a wind coming from the same direction, acting on the same local topographic features. The question is then, what suddenly made this strong wind coming from the south-southeast?

--Emily


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