Normally, I try to stick to Io and the Jupiter system on this blog, but occasionally I do pay attention to what else is going on in the unmanned spaceflight community beyond Cassini/the Saturn system and the Jupiter system. Last week, the MESSENGER spacecraft performed its last of three flybys of the planet Mercury before it will go into orbit around the planet in 2011. In response to this flyby, I finally decided to piece together one of the global mosaics from last year's encounter, which covered similar territory.This mosaic, consisting of 66 MDIS, narrow-angle camera images, was produced using a combination of ISIS3 (to calibrate and reproject each frame) and Photoshop (used to actually piece together each image). This mosaic could have been produced, I guess, entirely in ISIS3, but I found that trying to create a coherent control network that takes into account issues of camera twist angle and readily apparent range-to-target smear was a next to impossible task (I would like to apologize now to anyone trying to use Tethys in PIRL over the last few days while I was trying to create said control point network). The end result is the image you see at left.
Click Here to download the full resolution version of this mosaic. It would probably be best to just right-click and save the link as the full resolution version is a 20 MB PNG image file. Click the image above for a lower resolution version.
This mosaic is in orthographic map projection with a resolution of 0.6 kilometers (0.37 miles) per pixel. It is centered around 2 degrees South latitude, 322 degrees East longitude. The mosaic covers the eastern portions of the terrain covered by Mariner 10 in the 1970s as well as some terrain that wasn't revealed until the MESSENGER encounter on October 6, 2008. This terrain includes two ray craters at upper right and lower right that had previously only been seen in low-resolution RADAR data from Earth. The prominent ray crater just below and left of the center of the mosaic is Kuiper, previously observed by Mariner 10.
Some of the images from last week's encounter are slowly making their way to the MESSENGER home page, though versions that can be input into ISIS3 and converted into these huge mosaics won't hit the NASA PDS until sometime next year.
I hope you all enjoy this little treat. After I get some sleep, I will post more on some of the cool features you can find while searching around this mosaic. To be honest, my new favorite crater (at least on Mercury) has to be Rafael. In the morning, I will talk about why.
Image credit: NASA/JHUAPL/CIW/Jason Perry
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Great picture! Just wanted to point you to Hugin, an open source software that would allow you to piece together (and possibly reproject) your images automatically with a great degree of precision. http://hugin.sourceforge.net
ReplyDeleteThanks for the heads up on that software. For my last round of Mercury mosaics I made last year, I used PTGui to help with adjusting each image so that they would fit in a mosaic. Unfortunately, PTGui relies on knowing some information about the camera, like field of view, and the range-to-target smear definitely seemed to throw it off as well. It also helps if the camera is stationary for panoramas in these types of programs, like PTGui, which MESSENGER certainly isn't.
ReplyDeleteISIS3 is great for spacecraft images and I use the previous version, ISIS2, for all my Cassini processing. It just had issues with converging on a cleaned up control point network as a result of some issues in the MDIS images. I mean you would think that after measuring 900 control points that getting that convergence wouldn't be an issue, or at least fixing the inconsistent camera twist angle...
But I digress... thanks for the heads up.
Impressive. Now imagine what this guy can do if he was paid for it.
ReplyDeleteListen, this work is appreciated, and timely. We're deep into a comparison between Mercury and the Moon, along several different pathways, and this is a big help.
ReplyDeleteIt's also appreciated for the Herculean Labor!