Late last week I stumbled upon a few HiRISE derived DEM's (Randy Kirk works his magic once again!)
http://webgis.wr.usgs.gov/ftphirise/index.jsp (URL now down)
I'm working on both Vic Crater and the Columbia Hills. Fortunately, now I've got a Mac, I can use ISIS. I've figured out a fairly simple flow ( isis2raw as 16 bit unsigned, and then imported into Photoshop ) to take DEM CUB's and make 16 bit PNG's
Just to demo how important that is for me as an animator - sliced comparisons of 8bit vs 16 bit.
A busy week unfortunately, but animations of various sorts are in the pipeline.
Still figuring out the best way to explore and display these dems - especially the Colubia Hills.
Meanwhile - a revisit of an idea I had some years ago using a MOC dem. This is the 'power goodness' display - lit from the north in green, the south in red. A wider angle, and a close angle.
And using the Victoria one to simulate shadowing with the sun high in the sky, and as low in the sky as it gets ( 63ish degrees )
http://www.planetary.org/blog/article/00001395/
D
I've had a hard time trying to do justice to these data sets, the Columbia Hills and the Victoria Crater HiRISE Dem's.
Here's my effort for the Columbia Hills
http://www.unmannedspaceflight.com/doug_images/columbia_dem_480.mov
(4.8 meg)
Victoria Crater (with added 'rover') tomorrow
And Victoria crater
http://www.unmannedspaceflight.com/doug_images/victoria_dem_480.mov
3.8 meg.
Enjoy.
D
Cooler than a penguin sat on an iceberg, sucking an ice lolly and wearing underpants full of ice.
Agree, very very cool!
All that's needed to make us happy is to tack onto the end of the movie a little video of Oppy SAFELY driving out of VC!!
I rendered a jumbo 4kx4k fisheye then polar-to-rectangled it back into this.
It's hard to get the rover wheels to sit on the terrain when the terrain doesn't actually appear until you render it
I hope you all enjoyed the movies at full res courtesy of Emily on TPS's Blog
I'm open to requests etc. My favorite thing to play with is lighting, this is a particularly nice shot, although it does bring out the trouble with the CCD's.
http://antwrp.gsfc.nasa.gov/apod/ap080519.html
Doug
Well done! About time your work on these DEMs was recognised properly.
Magnifique!
Bra-VO!!! Superbly rendered...and appropriately recognized at last!!!
Just for fun, I actually have a better version on the burner right now Clouds, sun, haze etc. Results over the next few days.
These are great- nice job Doug!
I'm still looking forward to seeing more near-surface images or animations from HIRISE DEMs of other places that we haven't sent rovers to- these could be even more interesting than views of the familiar Spirit and Opportunity landscapes.
Well - there are four done for various Phoenix sites, but, how can I be nice about this....
They're dull. Very very dull.
I think many of the MSL candidates will get a DEM treatment, hopefully those will make it out the door as well.
Doug
Your work put everything in a new perspective and that's what exploration is all about
Hat off
Thanks
Congrats, Doug!
Unfortunately, the movie is almost invisible on my PC (it starts very slowly, then stops download after few frames...). Moreover, I do not find the old Emily's blog movies!
Some help???
I thoroughly enjoyed seeing these on TPS - why did I forget to say so right away? - Vertical scale looks realistic too, though Victoria's cliffs seem a bit rounded off.
The cliffs are a bit rounded off, just a symptom of the resolution (1m per 'pixel' for elevation) really.
And, to the very best of my abilities, they are accurate for elevation, as close as I could possibly make it. The clincher is that rendering the Columbia one from the landing site - it's a perfect replica of the success pan images of the hills.
The proper movies are here - http://planetary.org/blog/article/00001423/ - although I intend to update the Columbia one later today - links later Randy Kirk got some nice emails about them, which is good because it's his hard work that made the data, and his kindness that put it 'out there' for nutters like me to play with.
Doug
I didn't know it had been posted on there. I got an email from Randy who had got emails from people saying how cool it was. He told me, and then told Bob to edit the descriptor. Then we realised is talked about MSSS / MOC / MGS, and tweaked that as well. Then I realised Bob had linked to my highly unfinished and quite broken soon-to-be-blog.
Finished thing is now here : http://www.dougellison.com/?p=5
Enjoy
Yeah, went hunting myself...no joy.
Did enjoy the "sermon" post, though...
Doug, I perfectly understand the issue you described, I had same problem when I tried to realize a "power of 10"-like movie initially showing all the red planed and then zooming on one rover (Emily suggested such idea long time ago, do you remember?).
Now I solved the issue by making a dedicated POV-RAY script who shades between various textures with different scales, anyway I abandoned the mars-zoom idea due to absence of time (for the moment!). Anyway, this idea is working well only if you strongly zoom on a planar surface, so is not applicable to your 3D DEM... I think the best way to avoid use of mega-textures is to overlap a local, texturized "mini_DEM" surface on the big one, eventually using 3D terrain model computed from MER stereo cam (someting like this was available on venerable "Maestro" JPL software... now I do not know where to find it). In the outer parts, such mini-DEM should appear progressively shaded in order to have a smooth transition effect. I know is not simple, it is only a suggestion for possible, future works...
About your last treatment of the Columbia movie, I like it very much. My only observation is about the colors: personally, I would like more saturation, with different hue between red terrain and a yellow artificial sky... What do you think about?
I prepared this for someone else - thought forum people might enjoy it
1) Install ISIS 3 - instructions here http://isis.astrogeology.usgs.gov/documents/InstallGuide/index.html
2) While letting that happen - grab one of Randy's DEM's - I'm using the Victoria Crater bundle as an example
3) Find DEM_1m_VictoriaCrater.cub.gz (it's in the ISIS_EQUI360_OC folder ) and expand it
4) Run isis2raw
5) In the 'FROM' window - point to the .cub
6) Copy and paste the path and filename into 'TO' - but change the extension to .dem or something simiar
7) U16BIT data type ( screenshot attached)
8) Hit Run.... if this bit doesn't work - it's almost certainly your ISIS3 installation that needs looking at, make sure you got all the Base Data.
9) Find the .cub and open in text edit and find this part...
/* Core description */
CORE_ITEMS = (1278,1694,1)
10) Open Photoshop, and open the .dem.raw that ISIS3 produced
11) Width is the first of those three figure under CORE_ITEMS. Height is the second. Depth should be 16 bits, Byte Order as IBM PC, Header as size 0
12) Hit OK
13) Save out as 16 bit PNG, celebrate, have lunch, dump into your favourite animation package.
Gale Crater dem up
http://www.dougellison.com/?p=44#content
Doug
OK, now that's cool.
For those that don't want to or can't install ISIS3 I thought you might want to know how to do this using GDAL.
1.) Install FWTools (Lunix, Windows) or GDAL framework for Macs:
Linux, Windows: http://fwtools.maptools.org/
mac: http://www.kyngchaos.com/wiki/doku.php?id=software:frameworks
--Now I don't have experience getting these mac frameworks working. But I have heard it is easy.
once GDAL is installed and working, run:
1.) gdalinfo -stats DEM_1m_VictoriaCrater.cub (or GIS Tiff)
--note the min and max.
2.) gdal_translate -of PNG -ot UINT16 -a_nodata 0 -scale stats_min stats_max 1 10000 DEM_1m_VictoriaCrater.cub DEM_1m_VictoriaCrater_unit16.png
where
-of PNG = output format PNG
-ot UNIT16 = output type Unsgned 16 bit Int
-a_nodata 0 = Set all input NULL value to 0 on output
-scale in_min_value in_max_value out_min_value out_max_value = will apply a linear scale from input to output.
then just the input and output filenames.
That is it. It would be nice to know if this method works for anyone.
-thare
Note: I picked 10000 as the max scaled output but you may have to play with that value for your 3D app.
Doing an updated 2009 version of my Columbia Hills DEM. Bit of a bug in the first render, but should be finished tomorrow night.
Just got a new Core i7 860 CPU. My Q6600 has been retired to status of render node. New rig does these frames in about 35 seconds. Old rig in about 60 seconds - so I've nearly trebled my rendering power
FINISHED
http://www.dougellison.com/?p=82
Not perfect - but it's about the best I can do.
Like flying around - brilliant !
Robert
Love the dusty quality of the atmosphere. An easy post for tomorrow
--Emily
Hi Doug,
unbelievable job on the fly around! Thank you.
You say its the best you can do....but for me...that fly-around is the best I could ever dream about doing.
Cheers
I love how Spirit appears suddenly behind Home Plate. Very dramatic! Great job!
Superb.
on Mars, on Mars, on Mars...
Thankyou.
p
Doug, that's just...beautiful. With all the beauty the word can carry. Thanks.
I knew you were not going to sent the MER team "only" a postcard for the 3rd anniversary...
Very dramatic and beuatifull indeed, thanks.
Great animation djellison. I really like it a lot.
I never knew about the hi-res topography data on USGS, so I decided to download some of it for myself to play around with. I went and downloaded Victoria crater and it has everything in a .tif format (as well as the .cub files) and it all works except for the DEM .tif file. When I load it up in photoshop it's all black. I went and downloaded GDAL and loaded up the DEM .cub file and it shows up in there. I exported it as a .tif from there, but it still does not show in photoshop. Does anyone know what I'm missing here?
I haven't tried to work with the DEM data at all, so this is a shot in the dark, but my first question would be: is the file 16-bit, and if so, is all the data down in the first 12 bits? That's one reason things can look black in Photoshop. Check Image > Adjust > Levels and see if the histogram shows anything at all.
The file is 16-bit. And the histogram seems to be blank.
Well that's pretty much all my ideas. Guess you'll have to wait for the Sun to rise on the UK
This is the only way I know - so far - and it's very long, convoluted, and I'm SURE there is a better way to do it - but it works.
1) Install ISIS 3 - instructions here http://isis.astrogeology.usgs.gov/document...uide/index.html
2) While letting that happen - grab one of Randy's DEM's - I'm using the Victoria Crater bundle as an example
3) Find DEM_1m_VictoriaCrater.cub.gz (it's in the ISIS_EQUI360_OC folder ) and expand it
4) Run isis2raw
5) In the 'FROM' window - point to the .cub
6) Copy and paste the path and filename into 'TO' - but change the extension to .dem or something simiar
7) U16BIT data type ( screenshot attached)
8) Hit Run.... if this bit doesn't work - it's almost certainly your ISIS3 installation that needs looking at, make sure you got all the Base Data.
9) Find the .cub and open in text edit and find this part...
/* Core description */
CORE_ITEMS = (1278,1694,1)
10) Open Photoshop, and open the .dem.raw that ISIS3 produced
11) Width is the first of those three figure under CORE_ITEMS. Height is the second. Depth should be 16 bits, Byte Order as IBM PC, Header as size 0
12) Hit OK
13) Save out as 16 bit PNG, celebrate, have lunch, dump into your favourite animation package.
I'm hoping to figure out a workflow that involved just ImageJ or Photoshop without ISIS3 (as it's a hell of an install, and a pain in the butt to get running for a temperamental artists like me )
1080 Full HD version
http://www.archive.org/details/ColumbiaHills2009DemAnimation
Thanks to Gary Murphy for suggesting archive.org as a place to put it
Superb work Doug, it didn't go unnoticed on other websites & blogs
Nancy talked about it on Universe Today, Emily did the same on planetary.org/blog
Has it shown up anywhere else? It'd be cool to know.
I HAVE noticed that it's jumped to 9000 views on Youtube. I beat the 5000+ Helen got for her world record Thriller dance routine
Beautiful work as ever.
NASA Ames is working on a stereo pipeline for automated DEM generation: http://ti.arc.nasa.gov/project/ngt/stereo/
Their documentation has instructions for HiRISE. MOC and CTX are in there as well, although I will point out that their camera model for CTX is incorrect so any CTX DEMs created with this software are inaccurate.
Is this news?
http://hirise.lpl.arizona.edu/HiBlog/2010/01/20/first-pds-release-of-hirise-dtms/
http://hirise.lpl.arizona.edu/dtm/
If you view any of those fly-overs, be sure and set the QT viewer to full screen - the resolution is that good, and worth the experience. I'm not sure I would have taken the same flight path over Columbia Hills but it's an amazing ride nonetheless.
Not having the knowledge nor the time to make use of these DEMs myself, I hope some more enterprising members of this forum try their hand at producing some flyovers.
I've picked four favorites from the new batch - plus a few others from Pete - which I'll be trying to get rendered this week. Probably not as polished and pretty as the Columbia Hills anim, but they should be a bit of fun
Okay fine. I'll bug Trent next week when I see him. A while back MSSS did work with Larry Edwards that involved ASP. Since the open source release his custom camera models for MOCNA and CTX are no longer a part of our software. We now use ISIS to provide those. I hope to get this all worked out as a lot of our users are creating 3D models from CTX.
Trent got in touch with our software folks this morning and we figured out that the issue was the prototype vs. the official release of the stereo pipeline. Joe Fahle says that the camera model in ISIS was obviously wrong until iak/mroctxAddendum003.ti, but now there is little difference between the MSSS CTX camera model and that used by ISIS. So, it sounds like the newly released version should be all right...sorry about that, I was told not to use the pipeline because of this issue in December, after the "new" release, so I assumed the problem still applied.
The results of processing the new HiRISE team DEM's are beginning to appear. They're not as polished and pretty as the Columbia Hills one. Main reason is time. These are taking approx 1-2 mins per frame, at 750 frames each, so even with my i7 desktop, plus Q6600 render zombie (with occasional pauses for Helen and I to have some practice in dealing with the upcoming zombie apocalypse via L4D ) - it's 6-12 hrs each. So I had to turn down the 'pretty' quite a lot just to get through them in terms of rendering - AND in terms of processing. BJ's all new img2png helps speed up the processing pipeline massively.
Early results so far :
Athabasca Valles
http://www.youtube.com/watch?v=uQYDElIMQ2s
from http://hirise.lpl.arizona.edu/dtm/dtm.php?ID=PSP_002661_1895
Mojave Crater
http://www.youtube.com/watch?v=Fp8WU05W0Jg
from http://hirise.lpl.arizona.edu/dtm/dtm.php?ID=PSP_001481_1875
My render queue still includes Gale Crater, Bahram Vallis, Candor Chasma, Juventae Chasma. If you see a particular DEM from HiRISE and think " I MUST SEE THAT " - shout, and I'll see if it's worth animating.
Interesting how there's a crater right on top of the Mojave Crater wall.
But I suppose if you drop enough asteroids on a planet some will land in unlikely-looking places...
Still pretty wow !
Wow there's a lot of texture in those DEMs! Marvelous. Can't wait to see the rest.
Here's a couple of images created from the new HiRISE DEM's.
http://www.mars3d.com/mons.jpg
using the DEM from http://hirise.lpl.arizona.edu/dtm/dtm.php?ID=PSP_001432_2015
http://www.mars3d.com/gullies.jpg
using the DEM from http://hirise.lpl.arizona.edu/dtm/dtm.php?ID=PSP_001714_1415
- Adrian
It's done in the renderer as required by each frame - I've done actual models of most of these as well, up to about 1.2 million polygons, and in the near-field, these renders look better than those models. Certainly several hundred thousand in each rendered frame. Technically - you could pull about 50 million polys out of each one.
Man, am I glad I finally got a new computer for Christmas...fantastic work, all!!!!
Update : - Gale Crater uploaded
http://www.youtube.com/watch?v=Lh_bfrl9wk0
Dude, you made it onto the Huffington Post!
http://www.huffingtonpost.com/2010/01/27/mars-video-new-animations_n_439304.html
TOTALLY AWESOME.
Gold standard Forum this is!
Craig
I think it's being selective in not generating more polys than the are pixels to enjoy them - so in the distance, they are less dense. It regenerates every frame, producing the polys as they're needed. You can turn it up and down, and I basically turn it up till till it start having artifacts, or stops improving in detail. There are far better ways of dong it - you and Adrian have the know-how there. I'm just a tempramental artist
Its interesting to compare Doug's Mojave crater flyover to the flyover posted on the HiRise HiClips page: http://hirise.lpl.arizona.edu/media/. (The link to the movie itself is: http://hirise.lpl.arizona.edu/media/clips/mojave_v002_web_720.mov)
Interesting in what way Good/bad/indiferent
I prefer your lighting, and you have a better flight path IMO (which is entirely subjective). They have the drop on you with the texture overlay though.
Doug, your animations are great. The flyover on the HiRise site has finer detail on the ground, it seems. Maybe they made their animation with a different data set than the DEMs that they posted. Personally, I also prefer their color overlay.
Two more - http://www.youtube.com/watch?v=wswCRehrBNY - West of Juventae Chasma and http://www.youtube.com/watch?v=c4w4d_pfBS0 Bahram Vallis.
they are sweet doug - well done!
take a break now, otherwise you'll have nightmares about render farms and tie points. but hey, at least they'll be in 3D! that said, i'm still looking forward to your home-brewed DEM...
pete
I believe I can fly.
Thanks Doug.
Finally got the chance to watch these full screen and in HD. Just... wow. Greedily I await the next.
Just getting the data that Pete helped me make (in the same way a surgeon 'helps' a patient have surgery) into 3DS Max.
Early results = promising.
I'd amend that to
early results = awesome!
If this is only "early results", I can't wait to see the finished work.
It's rendering now. Start with Pathfinder pan view like that screenshot - fade it out to DEM - fly up and out, round the back of Twin Peaks - over to Big Crater, a high pass over to the top of the DEM, then fly back past North Knob to the landing site with a view of Big Crater, and fade BACK to the Pathfinder Pan.
Time for DEM hatrick....
One of Pete Grindrod's DEM's - Candor Chasma
http://www.youtube.com/watch?v=yaEdssbD1LU
One of the HiRISE teams - Slope Streaks (NW scarp slope of Olympus Mons, I beleive)
http://www.youtube.com/watch?v=GQFyW4a-oDw
And the one I've been dreaming of for 3 years. Mars Pathfinder. DEM by Pete (with hindrance and biscuits by me ) last week.
http://www.youtube.com/watch?v=uE_Ih0hgnlw
Fantastic animations! Congratulations, Doug!
Go ahead and take the rest of the week off Doug and send me the tab for the first round at your favorite bar tonight.
When I first popped the pathfinder pan back over the pathfinder dem.... I swore quite loudly.
"**** off, no WAY is it going to match that well"
And it did.
I'm trying to improve it with an HRSC or CTX image as a virtual table-cloth under the place-mat that is the HiRISE dem. Sadly - the HRSC DEM of that site isn't available ( as far as I can tell. There were two observations on that orbit. 3147_0000 and 3147_0001 gues which one's pathfinder. Now guess which one's got a DEM available on ESA's PSA... yup - the OTHER one)
Doug,
Simply amazing. When you redo this one, can you add a few seconds pause after a slow fade back to the Pathfinder pan? That would be great.
I'm doing a MAJOR 2.0 that's quite different - but will end with a fade probably, to the twin peaks.
It starts about 20km above the deck
For some reason only Quicktime wants to play it smooth... for anyone with older machines...
Really is gorgeous, thanks for sharing.
Eoin
Man, oh man...watched each several times, never gets old. Thanks, Doug!
Truly excellent work Doug, I've toured the Pathfinder site a dozen or so times now, thanks to you!
Now, if we can just get you and James Cameron in the same room, maybe, just maybe, the two of you can bring "Red Mars" to the big screen...!
Very nice work!
This was raised over in the Opportunity distant vistas thread, but I think this is probably the better home for it.
After helping Doug make the Pathfinder DEM, we were trying to figure out how well it matched up with the panorama from on the ground (suspiciously well!). So using the same method as in the other thread, here's my attempt at trying to show the distant features that show up for something about 1.5 m off the deck at Pathfinder's location.
Here's a hillshade basemap of the DEM, with a colour map overlain. I had to stretch the colour to show off the subtle topography at Pathfinder, hence the cut-off at big crater. You can also see the only error in the whole DEM near the top. The red dot is Pathfinder.
What a fantastic and useful technique Pete! The work you guys are doing is amazing!
What was amazing was that just the very tip of North Knob was visible - and bingo, the Viewshed called it out perfectly.
just out of interest, here are a few quick views of the pathfinder area ("twin peaks" and the area immediately surroundig the lander) rendered using the single-image shape-from-shading (SFS) method described in the other thread ...
You used the annotated one
I'm having some problems with the DTM .IMG files from the HiRISE site. It seems like the same (or similar) problem I was having back in page 4 of this thread.
I'm using the latest version of FWTools (2.4.7) and I can open up the .IMG in OpenEV. But I can't convert it to a .jpg, .bmp, .gif, or a .png file. It just says "unable to create output file...". When I try converting it to a .jp2 or a .tif file, it appears to work, but when I open the exported file into photoshop, it's completely black in the .tif file and completely grey in the .jp2.
Does anyone have any idea what's going on? Is there something I need to do to it before exporting it to another file format?
Use Bjorn's latest version of img2png - it'll turn it into a PNG for you.
Thank you djellison, that worked.
Now to see if I can do anything interesting with them in 3dsmax
Seems like the video's are still entrancing new fans, just noticedhttp://gizmodo.com/5495401/the-most-accurate-flyby-of-mars-to-date picked it up via Twitter from Roger Ebert.
Edited - I just noticed Emily's comment on the Discovery article regarding the attribution of the video and corrected my own mis-attribution. Hangs head in shame.
Yup - it's Adrians awesome work. Mine don't look anywhere near as good, and mine take minutes per frame, rather than 30 frames per second.
I've emailed the Gizmodo writer, commented at Discover, hopefully they'll get the message and correct it. Adrian is the one who deserves the credit for this, not me!!
New DEMs have been posted on the HiRISE website http://hirise.lpl.arizona.edu/dtm/.
Maybe some of the imaging wizards on this forum can use them to create flyovers, oblique views... I wish I could try it myself, but I don't have the tools to do it, nor the time to learn how to do it (there's a thing called "work" that gets in the way). I know everybody here has his own occupations, so I understand that it's not possible to fully exploit all those goodies.
Hi all, I've finally had enough free time to do some more animations based on the HiRISE DTMs. I hope you like them.
http://www.youtube.com/watch?v=GTum-TUol3k
http://www.youtube.com/watch?v=ftS4rujxJWo
http://www.youtube.com/watch?v=D-wc7f_V1fY
http://www.youtube.com/watch?v=7J8nbuKyLPs
Just totally awesome, especially when viewed in full-screen mode!
Absolutely. Freaking. Spectacular.
Thank you!!!!!!!!!!
Meh.
Mars3D:
Finally I downloaded your animations (HD) and with proper music, it's really ecstasy!
Thanks for kind words.
I have uploaded some more videos, these ones are in 1080p format.
They were created from DTM's I've used in previous animations but the paths are different.
http://www.youtube.com/watch?v=k7ji4wM74wo
http://www.youtube.com/watch?v=QutMf79sFhk
http://www.youtube.com/watch?v=SyeK-q31c-Y
You'll need to manually select 1080p for the best quality as it usually defaults to 360p.
- Adrian
Hi JRA,
I have 4GB of ram (only 3GB is usable because I'm running a 32bit OS) The maximum image size I have been able to load into system memory is 32768x49152. Because its greyscale it uses 32768x49152x1 bytes which is 1.6GB. The image is then broken into tiles in memory and a cache of visible tiles are stored on the graphics card, so although I have a graphics card with 1.5Gb of RAM I think 512MB of video RAM would work ok to.
Some of the dataset images are bigger than what I can load into system memory e.g. Mojave, so I have to crop them. A 64bit OS with 6GB of RAM would allow me to not crop any of the datasets and run at the maximum resolution.
I am using a dual core CPU @ 1.8Ghz, CPU speed is not a limiting factor and mid range GPUs can handle the number of polygons I'm rendering. The biggest issue is the high system memory requirement.
I don't know 3dsmax so I cant give you any advice on that.
Hey, thanks for the reply and information. I think I'll have to stick to chopping them up into bite sized pieces for now then.
These are all great visualizations of the HiRISE elevation data, Doug your flyovers are simply superior. I am still crashing my spacecraft through the surface or veering off into the vast whiteness of space. I also think your layover http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=20575 is outta this world, literally.
I wanted to visualize how the Gale Crater (msl study site) surface projects itself in terms of different sensors, as well as between the 10 adjacent HiRISE dtms listed on the map. A two-framed “flashing” movie http://www.flickr.com/photos/marsmojojojo/9540049251/ is an example of feature dislocation at the edge of the orthographic images. The map below projects those differences at 50-meter breaks spanning the 10 HiRISE dtm extent. The difference at the edges (featured in red) is most apparent in the Northern portion of the image. The hilly terrain to the south values are offset slightly compared to the Northern portion, but still visibly offset by some tens of meters in places. This offset affects the mosaic, and every model I run afterward, which is in conflict with my longing for order, especially in the overlapping regions of the map at larger extents. I have a couple ideas I may try but my mars time is slipping away rapidly to studies of a more earthly nature.... If anyone has experience geo-referencing or creating orthos I would greatly appreciate your comments.
Any HiRISE DTM (and I assume HRSC DTM ) gets matched to the reference MOLA data. In same cases, there might only be one or two MOLA points within an entire DTM with which to do that.
The uncertainty of MOLA, the sparsity of its data compared to the HiRISE or HRSC footprint, the size of a MOLA footprint, and os on and so forth - this results in the differences between neigbouring DTMs.
It's a non-trivial task to remove those differences - one which I know some developers here on lab have tried to solve using a gradient domain solution that took several months.
RRussman, each DTM is ortho rectified an as such they are projected on a flat plane but each DTM is projected on a different plane so at the edges the planes exhibit the largest co-registration error. You would need to re-project all DTMs on a common plane but besides being non-trivial, the map you obtain is not really "ortho" anymore as you would have significant distortions. The other thing you could do is to project each DTM on the spheroid and then do a cylindrical projection. There's no good solution and what I do is to just work on one DTM at a time (currently still on PSP_010573_1755).
Paolo
One lesson to take from this is that DEMs and associated orthophotos look beautiful but are not gospel. You have to treat them with a bit of suspicion.
Phil
Doug, I’m pretty sure everything is matched to MOLA after 2000, but as you point out, the sampling is sparse even along track. By sparse I mean there are 48,211 mola points (PEDR) over several tracks/orbits in the map extent, and yes, some dtms are far more populated than others are. The HRSC and HiRise products are continuous data sets with much finer resolution. An excerpt from the literature on the resolution mismatch:
“Because of the low horizontal resolution of the MOLA data set compared to HiRISE images, vertical accuracy will likely be governed by the difference between localized topographic features and the broader-scale relief as measured by the altimetry, and may be several meters. The resolution mismatch between the two data sets is likely to make direct use of MOLA for horizontal control almost impossible. Our approach is to control lower-resolution images to a shaded relief product generated from MOLA data gridded at 1/256 or 231 m/pixel, then to transfer control from these images to the high-resolution stereopair.” (McKewen, etal, 2007) (fromhttp://onlinelibrary.wiley.com/doi/10.1029/2005JE002605/abstract, access required for full text)The discontinuity is most noticeable in the northern portion of the map with the DTEEC_010573_1755_010639_1755_U01 appearing offset more, relative to the adjacent overlapping regions, as well as the general flow of the collective model at multi-product extents. It might simply be that this model received less rigorous processing to the north and away from the msl region of interest.
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