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Galileo images and mosaics of Europa
DrShank
post Sep 5 2014, 08:08 PM
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QUOTE (machi @ Nov 1 2011, 12:39 AM) *
Thanks,
Accuracy of the stereograms Fig.5 and Fig.6 is dependent on the precision of my eyes and my experience.
Stereograms are made by warping in Sqirlz Morph using manually added control points. With these images, I achieved my personal record - more than 1800 control points.

"I have now 'discovered' that there actually is stereo coverage of Conamara Chaos but unfortunately it's not the very hi-res E12 stuff - it's E6 images from ~19000 and ~6600 km."

I used image, 7513R from orbit E6. This image covers whole mosaic, so theoretically whole mosaic can be done in stereo with similar results to Fig.5/6.

"And finally let's not forget this great stuff from Paul Schenk:"

Yes, I know his masterful work, after all Paul Schenk is guru of DEM models. This is reason why I'm doing stereograms and not DEMs. smile.gif

I made little comparison, with similar geometry, between stereogram from two images with ~same resolution (1900 and 1913 from orbit E12, Fig.3) and
manually warped version (Fig.5), so you can judge both versions. Fig.3 is right image and Fig.5 is left image.



always nice to see these products get some attention! be in known that i am finally (!) at last putting the stereo and PC DEM story of Europa together for submission later this year, complete with a web page of jpegs and the like. it will take 2-3 months of work to get everything ready for release but it should be pretty cool. soon . . . !


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tedstryk
post Nov 21 2014, 08:14 PM
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NASA has released an exquisite new version of Galileo's best global view of Europa along with a nice promo video for exploring it.


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Bjorn Jonsson
post Nov 30 2014, 05:32 PM
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It is a pleasant surprise to see this released after all these years. This is a very high quality mosaic, the best version from these particular source images that I have seen. A very 'clean' image and the color channels are perfectly aligned (I sometimes need to warp indvidual color channels slightly to get rid of small 'residual' alignment errors when processing color images). The color isn't as realistic here as in Ted's version though since the red channel is from near-IR images and this is not corrected for (at least not fully).

For comparison, here is a test render from a 20000x10000 pixel true color global map I'm working on. It's shaded using a slightly modified Hapke function:

Attached Image


As should be obvious, this is not the final version of the map. The poles look strange and the color may change a bit in later versions, at least in the northern hemisphere near the terminator. Actually it is remarkably difficult to create a global true color map of Europa. The surface contrast varies with phase angle (less contrast at low phase angles) and the color also varies with changes in viewing/illumination geometry. Or in other words, the photometric parameters vary with wavelength. For example limb darkening increases with increasing wavelength. I haven't found any information on exactly how the Hapke photometric parameters vary with wavelength but if I find information on this (or figure out myself how the parameters vary) I should be able to render more realistic views of Europa uisng the big map I'm working on.

QUOTE (DrShank @ Sep 5 2014, 08:08 PM) *
always nice to see these products get some attention! be in known that i am finally (!) at last putting the stereo and PC DEM story of Europa together for submission later this year, complete with a web page of jpegs and the like. it will take 2-3 months of work to get everything ready for release but it should be pretty cool. soon . . . !


It will be very interesting to see this.
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Bjorn Jonsson
post Dec 20 2014, 10:51 PM
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One by-product from the 20000x10000 global map of Europa I'm working on is that I now have a global true color map from all of the useful color images that have a resolution ranging from ~1.2 km/pixel to ~15 km/pixel and this can be used to colorize clear filter images and mosaics. Here is a colorized version of the I25 mosaic in this post. The color is mainly from the C9 global image but a bit also comes from G2.

Attached Image


The color should be fairly close to Europa's true color.


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nprev
post Dec 21 2014, 12:24 AM
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Gorgeous, Bjorn. blink.gif


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jgoldader
post Dec 22 2014, 02:41 AM
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Bjorn Jonsson
post Feb 2 2015, 10:40 PM
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Today, it seems that NASA is at last committing to flying a mission (probably Europa Clipper) to Europa after years of studies. By a strange conincidence, on this same day I may have finally finished the 20000x10000 pixel map of Europa I've been working on for almost 2 years (!) (but with major breaks to do several smaller projects). All that remains is to check for images I might have overlooked that I should have included in the map (I don't expect to find any). The map should include almost every image down to a resolution of ~200 m/pixel plus a selection of several higher-res images.

Here is a 4000x4000 pixel test render showing the hemisphere with the best imaging coverage, including a pole-to-pole strip left of center at higher resolution than most of the map.

Attached Image


Due to upload size limitations I couldn't upload a bigger version here; a bigger (6000x6000 pixels) version can be seen here: http://www.mmedia.is/bjj/data/europa/europ...b_6000x6000.jpg

I'm looking forward to the day when *all* of this terrain has been imaged at better resolution than here by JUICE and/or Europa Clipper. I want my Europa map to become completely outdated as soon as possible!
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Explorer1
post Feb 2 2015, 10:42 PM
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Desktop'd as usual, Bjorn.
Not much else to say... fantastic as always.
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stevesliva
post Feb 3 2015, 01:21 AM
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QUOTE (Bjorn Jonsson @ Feb 2 2015, 05:40 PM) *
Here is a 4000x4000 pixel test render showing the hemisphere with the best imaging coverage, including a pole-to-pole strip left of center at higher resolution than most of the map.


I noticed that and assumed that was where Galileo had images things at a higher resolution... am I to understand to that the entire hemisphere has similar resolution in your map? Wow.
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Bjorn Jonsson
post Feb 3 2015, 11:08 AM
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No, not all of the map has this resolution. This north-south strip is from Galileo's ~200 m/pixel regional mapping which covers a relatively small part of Europa (probably most/all of Europa would have been imaged at this resolution or better had Galileo's HGA worked). In addition to this N-S strip there are several more areas at similar resolution but most of the map comes from images with a resolution of ~1.5 km/pixel. There are also areas where the source image resolution is lower though - only 4-15 km/pixel.

The map's size (20000x10000) translates into slightly better than 0.5 km/pixel resolution where the source data allows.
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Ian R
post Feb 3 2015, 12:25 PM
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A mighty congratulations are in order, Bjorn! The culmination of a two-year project of this magnitude is something to be celebrated, and I hope you get the recognition and plaudits that this achievement so richly deserves.

Ian.


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algorimancer
post Feb 3 2015, 03:06 PM
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The full resolution version is pretty amazing -- someday it would be really nice to have a Google Earth version, like we have for Mars. A lot of details pop-out which I hadn't dwelled on previously. There are a scattering of large berg-like features, almost like boulders lying partially submerged in the surface; if we posit the thin ice shell model, these may arguably be spots where the shell has doubled-up (stacked one layer on another). I'm out of touch with Europa research, but it seems like someone ought to have studied these in depth, perhaps modeled and measured their displacement of the surrounding surface, perhaps established whether they are in hydrostatic equilibrium. Neat stuff.
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machi
post Feb 3 2015, 11:55 PM
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True masterpiece Bjorn!
It's really pity that we haven't good topography data. It would be really tempting to combine your excellent map with some nice topography data.
Hopefully it will be possible some 20 years later with data from new Jupiter system missions.


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tedstryk
post Feb 6 2015, 12:36 AM
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Beautiful work, Bjorn! That may be the smoothest looking global rendering of anything from Galileo data I have ever seen.


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Bjorn Jonsson
post Feb 18 2015, 08:55 PM
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My brand-new 20000 x 10000 pixel map of Europa can now be seen here: http://www.planetary.org/blogs/guest-blogs...ing-europa.html

This is by far the biggest image processing project I have ever undertaken in terms of time and number of images (but not complexity). I now have a big directory tree associated with this image processing project; it consists of about 50 GB in 2500 files and 135 folders (!). A lot of it is temporary stuff though that can be deleted.
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