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How Spirit Takes Pictures
Some Clown writes "MSNBC has a great article on the details of the camera system on the Mars Rover titled How Sprit makes great photos. Apparently the high resolution images are all done with a 1-megapixel camera. All the money is in the CCD and Lens. The hardcore digital photographers in the crowd will probably find the article to be only a teaser on the technical specs, but the rest of us in the unwashed masses should find it interesting."
The hardcore digital photographers in the crowd will probably find the article to be only a teaser on the technical specs, but the rest of us in the unwashed masses should find it interesting.
What does having a six-digit Slashdot UID have to do with digital photography knowledge?
You probably shouldn't click this.
Why not link directly to the original article?
The unofficial
It is also interesting to see how it produces color photos. Instead of using a 3 color sensor, it uses a B&W camera with 3 colour filters that recombine into a colour image. This is calibrated by a colour wheel on the rover itself.
Neat stuff
Somehow I don't see the phrase "shake it like a 1-megapixel digital camera" being as catchy
High quality images are good for PR, but what I really want to know is how it extracts information from the environment, how this information is being used, and whether or not we found anything we didn't expect to find.
~To choose doubt as a philosophy of life is akin to choosing immobility as a means of transportation. -Yann Martel
I am not trying to be negative, I think what they are doing is great and long overdue. Can't wait till we have Rovers on other planets. But why did it cost $400 million? I've read about what Rover is and how it was built and what it does. I am sure it was expensive to build but $400 million? Does that include the cost of getting it there?
I dunno, That would suck if all Spirit's pictures had a finger in the bottom corner of them like all mine do.
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Humans to the moon (1969)
Digital cameras to mars (2004)
Internet Fridges to pluto (2010)?
Is this progress?
It is interesting, but I suppose it is explained because this sort of tech has to be (physically) tested a couple+ years in advance (and 2 years is in the final test/construction phase already, initial planning was years before), so strapping the latest untested camera in to a planned and tested system would potentially introduce a weak point in the system. Yeah, pretty nifty, kinda shows the potential 'old' hardware has when used to its full potential.
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FreeNET user? Comfortable with the adverse selection?
So, digital camera's and Tang are the practical spin-offs from the space program. cool.
It's important to note that in a color digicam each "pixel" only senses 1 color. The NASA cam is a black and white, and to make color they take 3 shots with different filters. This makes it equivalent to a consumer 3MP camera.
They also have a nice lens and a large sensor which helps as well.
Tim
Resolution in cameras (both digital and film) is really determined by optics. By taking pictures of a smaller area and stitching them together, they can probably get better pics than most pros get with their high end Digital SLRs, because they've put more money into the optics than the sensor. Also, the higher density CCDs and CMOS sensors going into digital cameras now tend to be more prone to noise than some of the very high quality, lower density models.
Also, remember that the cameras in the rover had to go through a lot more testing than a typical consumer camera, so it's probably using three, four, or even five year old components in the imaging systems.
It's good to use your head, but not as a battering ram.
No, I read it; obviously the sensors in my little 1MP cam won't be anything near what's in the pancam, but I can do something about the lens. Grab an eye doc friend who can get some decent prescription-ground lenses and go for the stereo effect. I'm not sure; one might have to write a small program to make it work, but it could be fun to see the results.
The NASA guys had to start somewhere. Their biggest advantage will be the sensors, but there's no reason we can't replicate the rest. If one wanted to go all-out, it might even be feasable to use an array from a high-mp camera and configure it to use multiple sensors to produce 1px.
Damon,
http://actionPlant.com
Actually, it's only 1 megapixel because it's a cameraphone. Sprint donated the phone in exchange for showing off their new Martian-wide network. The lander just waits until 7pm so it can send home pictures using free nights and weekends. Unfortunately the budget killer is the shots from the rover since they incur roaming charges.
"Sorry, your browser is not compatible with this feature!"
@%**! MSnbc
Click on the "Interactive feature" if you don't know what I mean,
then curse microsoft,
then go straight to http://marsrovers.jpl.nasa.gov to see the images without paying the microsoft tax. I vowed a long time ago to stop clicking on msnbc links.... sucker that I am to keep coming back for more...
Nasa uses a 1MP camera but 3 filters. The 3 filters are combined to give you a color image.
Consumer 1MP have the same number of pixles buy each pixle has only 1 filter. The image is then interpolated to get a true color image.
Even if your optics and ccd were the same quality as Nasa's you would still only have 1/3 the resolution.
Serious question here... the article says "One megapixel is a million pixels set up in an array equal to 1,000 by 1,000."
Is this like hard drives using one GB = 1,000,000,000 bytes or is 1MP truely 1,000 x 1,000 and not 1,024 x 1,024?
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"And may your days be long upon the earth."
Many believe buying a better camera with greater megapixels etc will make them a better photographer. Sadly mistaken are they.
A great photographer can take an old Brownie and develop some GREAT photos...
Anyone can point and shoot a digital camera...but it really takes someone with talent to get a GOOD image using one.
The greatness of a digital camera is you can snap those 500 shots to get the 3 good ones and not worry about film and developing costs...
Professional wedding photographers shoot 300+ pics per event and rarely get better than 25% that come out with any sort of quality, but people buy them just the same because of 'who' is in the picture.
Anyway just a rant on about people who think the latest and greatest will actually help their choice of shots, lighting, and perception become better...
"Just Smile and Nod." --Huck
"NASA's Spirit Rover is providing a lesson to aspiring digital photographers: Spend your money on the lens, not the pixels."
Every good photographer will tell you the same. It still amazes me that people are willing to drop Can$.5k for a digital camera, but think you are nuts for spending the same money in a lens.
Too bad the digital cameras all come with Zooms. At the same price, a zoom lens will tend to be worse than a fixed lens. An old camera, the yashica t4 super won a great reputation for its superb fixed lens (35 mm Carl Zeiss).
I have one, and I love it. It takes the best pics I have ever seen in a P&S.
That's not all- the images are clearly composited, which is why they look so stunning(yes, the huge, low-noise ccd helps, as does a great lens). The very first image released(the 8mpixel one) had a very very obvious stitching error right smack down the middle, which is pretty bad, considering that with a robotic rig and known lens characteristics, you should be able to stitch the image exactly(most errors in stitching software comes when you didn't shoot the images perfectly overlapping, or at different angles, or you took a step forward/back, etc.) You can buy software off the shelf that does a better job than NASA's job.
"How much so a man can walk on mars?"
Please help metamoderate.
I read somewhere after the lander, um, landed that the pictures it were sending back were flawed. The arguement was that Mars, like Earth, was supposed to have blue skies. I can't say that this is a correct assesment but it seems plausible. I do recall watching C-SPAN last week or the week before when a group was talking about Spirit. One thing they talked about was a simple little 4-color chart that could be used to sync Spirit's camera color settings to once the rover landed. The plate the color chart was on also doubled as a sun dial (low tech at it's best!). Anyhow, I thought the blue sky idea was interesting. Is the red planet really red when you're standing on it's surface?
Here's a story about some of the software involved.
Brady
I'd imagine it's more to do with radiation hardening, they could have, for a paltry sum, put a top-of the range con/prosumer camera up there and if it broke, no big deal, but it wouldn't survive outside the protection of Earth's atmosphere, the smaller alectronics would be fried by radiation from the sun in no time. Radiation hardening is great, but a difficult, complicated, "fiddly" procedure, so basically all the tech on the shuttles are a lot less advanced than the stuff we take for granted here on Earth. They wouldn't survive space if they weren't.
I am not very surprised that no journalist understand that, I am more surprised that /. readers missed the point: it is simply nonsense to say that the camera is 1M pixels.
/. readers, please, if you are geeks, always read the small lines. Do not expect NASA or a journalist to do that for you. It is not the interest of the former, and the latter is just stupid.
Indeed, the CCD has 1 million pixels, but look at the published pictures: they are assembled from a great number of small 1 megapixels squares!! Simply have a look at the raw pictures on marsrovers.jpl.nasa.gov: some of them are not fully transmitted yet, consequently parts of the pictures are black.
To make a "normal" picture, like one you would naturally do with your 5M pixels camera, the pancam needs to take shots from, say, 20 different angles. And it is even worse than that: each pictures must be taken 4 times with each filters to get colors. Do not even dream of taking photographs of moving subjects!
There is another drawback: there is two cameras, for stereo. But if you look at the tech specifications on Cornell website, you'll see that each camera has filters that can cover only one half of the color spectrum. Hence, to get color pictures, you have to combine the photographs taken by both the left and right cameras. That's why there is some weird colored patterns on big objects: to put it simply, the left camera sees the red, the right one sees the blue! But both cameras do not see exactly the same thing!
And nonetheless, there was a hint: do you really expect 1M pixels raw pictures to weight 7MB? Huuh?
Yes, the camera is 1 megapixel, but the published images are often made from multiple* shots, sometimes hundreds: for instance the panoramic images.
*No, I am not refering to 3 shots it takes to get red, green and blue data for each pixel.
I understand that thermal noise can be a cause of noisiness in CCD images. Do the low temperatures on Mars (or in cold places on Earth, for that matter) have any significant effect on digital photo quality? Could the cold temperatures on Mars be taken advantage of to maximize the quality of images taken there?
Weeks of coding saves hours of planning.
Or, am I correct to assume that the atmosphere on Mars (or lack of it) does not propogate sound waves, so there would be nothing to listen to???
The article implies that the camera is monochrome and that filters are used to capture each color.
So, adding the images together, 1 megapixel green + 1 mp red + 1 mp blue = 3 megapixels.
Yeah, that's great for taking pictures of things that aren't moving, but if some fast-moving martian zips past Spirit, all we're going to see is a low-res blur!
"Freedom means freedom for everybody" -- Dick Cheney
"Perhaps I'll dust my old 1MP camera off and see if I can do anything similar."
You're going to send your old Sony Mavica to Mars?!?!?!?!?!
A lot of people see the prints from my digital SLR, a gracefully aging Nikon D1h and are astonished to learn it's from digital. Most then refuse to believe it's only a 2.7mp camera.
Near all my pictures at www.gavincato.com in the photography section are with the Nikon D1h.
The Nikon D1h has only a 2.7mp sensor, but the output is fantastic. The pixels are large, and the noise is pretty low. It's pretty much noiseless until you hit 800 ISO, and even at 1600 ISO it's significantly better than 1600 speed film.
NASA is very correct in saying the lens & sensor are important, for example most of my lenses are ludicrously expensive (often more than the camera body) and the majority of them are fixed length lenses and thus have incredible optics.
I've previously owned a Nikon D100 which had 6mp, but I found to my surprise that I preferred the output & prints from the D1h. I originally bought the D1h to complement the D100 (the D1h is a crazy fast camera designed for sports), not replace it, but after a while I ended up selling the D100.
The guys in the Canon camp have said the same thing, they much prefer the output of the 4mp Canon 1D vs the 6mp Canon 10D.
Most digi-cams say that they are 3MP, but keep in mind that for any given pixel requires four elements (RGGB) to create. I believe the Spirit camera is only sensitive to light, and has interchangable filters (so it must make three passes to get full color) -- effectively tripling the "element count" of the sensor.
You quitting proves that the karma kap worked. The most annoying of the whores shut up. --CmdrTaco
Are those really fake rocks? Interesting how they look so much like the real thing. Martian cilization must have been great indeed for them to be capable of such painstakingly accurate forgeries of pebbles...
I'd say the biggest limit on the size of the images is the bandwidth to Earth. The links are getting faster but still nothing compared to a typical DSL line.
One thing I've been wondering, and maybe someone out there knows more. What kind of image compression are they using?
They mentioned that the design process of the Huble's CCDs at a resolution of 800 x 800 contributed to the current mass production of consumer CCD cameras, so I don't think they are afraid of pushing the envelope if it is needed to meet mission requirements.
question. is your 1d full frame? that would easily explain why it's got better iamges than the 100d.
i'm one of those int he canon camp and i do have to concur with you on those findings. my canon has an APS sized sensor and can take very noise free iamges upto 400 ISO, at 800, it's still useable.. and i've done 1600 ISO shots, but i only use it if i have no other choice.
one thing people don't understand is the extra MPs only matter if you want to blow up your images. most people rarely print bigger than 4x6" and at the largest 8x10" 3MP resolution is more than good enough for an 8x10" print. after that, you want the best out of those MPs... NOT more MPs.
I believe sex is highly over rated... unless it involves me
Whatever it is, I'm pretty sure it's lossless. The pictures (no matter how snazzy they look) are intended for scientific research. There wouldn't be much point spending millions on optics to ruin pictures with decompression artefacts.
As for the actual encoding -- considering the article states that the cameras don't work like normal cameras and instead red, green, blue components are built up separately -- I'd say it's something NASA cooked up just for these probes.
If you follow that link and see the forbidden image of a Zero-Point Energy module left behind when the Grays dumped Elvis' worn-out second body on Mars back in 1972, you're just asking to disappear one of these days.
I know it is a lossless format, so it obviously isn't JPEG. I would guess that they are using some form of RLE (run-length encoding), perhaps combined with a Huffman table for the shading values. I wonder what the pixel-depth is.
the sensor advetized as a "2mp" sensor typically has a bayer pattern. since the sensor can only record B&W information, they put a patter of RBG filters in front of each sensor lement like so:
RGRGRGRG
GBGBGBGB
so your 2mp sensor is capturing 500k pixels of red tones, 500k of blue tones, and 1M of green tones.then software will interpolate this pattern into a 2mp image with all three colour elements.
I believe sex is highly over rated... unless it involves me
to produce decent digital pictures. In fact, having very large number of pixels introduced lots of noise. The latest Sony camera - 8M pixels - is a good example. The camera simply isn't good. High level of noise, and color abberations. They've crammed too many pixels in CCD with the area too small.
OTOH, the high quality lenses and high quality post-processing of captured image are important factors in getting decent digital pictures. Yet 'unwashed masses' only understand one thing - the magic pixel number.
His name was Sergei Mikhailovich Prokudin-Gorskii, and they're awesome. You have to remind yourself of the time period when you see them, or you'll instinctively think they're more modern:
http://www.ummagurau.com/art/russia/
I don't know which is more depressing, that 2/3 didn't care enough to vote, or that 1/2 of those that did are crazy.
Maybe because spending millions of dollars on a space mission entails rigorously testing every piece of equipment which could take years before the launch? And as the article pointed out, this is not your off-the-shelf digital camera so an extra-thousand bucks will probably get you nowhere near the quality you'd otherwise expect from off-the-shelf accessories.
What color was it before the picture was edited and if it wasn't "peach", why does NASA think we need to see a pink Martian sky? What happened to the blue sky that Viking showed us? Just wondering if anyone else has noticed this.
Shut up and eat your vegetables!!!
I am not surprised at all, and I am glad to see that NASA didn't fall for the marketing hype that the number of megapixels is the determining factor in the quality of a photographic image. Personally, I would prefer a 1 megapixel camera with an SLR (single reflex lens) to 5 megapixel camera.
I believe the secret to art is the process used in filtering down to the information that you really need in a picture.
The two areas that you miss with smaller megapixel cameras are textures and fractal patterns such as the shapes of leaves, forests and grassy fields. However, when you really need to study a pattern, you can zoom in (assuming you have a decent lens) and get the information you need.
I think 1 megapixel is the right image size for the job at hand. Of course, all the pictures from Mars with trees and grassy fields will be a bit fuzzy. Those of rocks, landscapes and strange green alien creatures will turn out fine.
For those not familiar with it, the multiple exposure they talk about in the article has been long used in the darkroom and can be done easily with modern scanners with good software. It brings out extreme details in parts of images that are normally burnt out.
Take a single slide that you scan. With a program like VueScan, you can set the exposure of the scanner, so you can do a dark scan (thus exposing properly the light part of the image), a normal scan and a light scan (exposing the dark part of the image).
Import all 3 into a graphic program, superimpose them and cancel the parts that you don't like (which is the creative part and not as easy as it seems).
Note that you can also do that taking 3 pictures with various exposure with the camera on a tripod, and it's the way the Mars rover does it.
Non-Linux Penguins ?
huh? To get stereo, you need separation. You could do this with a couple of prisms, or maybe the biggest fresnel lens you ever saw, but why not just move the camera sideways between shots?
If your camera can take several pix in a row, use that, and simply move the camera laterally during the shooting (assumes you have fast shutter time).
Lastly, no. As I understand it, a CMOS sensor cut into 1000x1000 pixels will give you "better" pixels than the same die at 2000x2000 pixels, and coupling the pixels 2x2. This has several causes:
1) you can only average your combined pixels after sampling: thus you get quantisation noise (and hypothetically phase interferernce, although I've never heard anyone comment on this)
2) if you couple 2x2 pixels, you will get 1xR + 2xG + 1B pixels. Most pixels will be predominantly one of these colors, removing the other 3(2 for G) from the picture. This also means that a blue photon heading towards the 2x2 metapixel must hit the 1/4 area which can see it, else it is lost.
3) (I don't quite get this one. As close as I understand it:) The size of the sensor feature size is coming close to the wavelength of light: Sony's new 8mp sensor is 0.008 m long, with 3000 pixels. That makes each pixel 2.6e-6 m. Compare with Red light, at a wavelength of 0.7e-7 m. Each sensor is three wavelengths wide(!). This apparently means that you can't usefully use an fstop higher than 11ish on the new sony f828. Search photo.net for a technical discussion.
4) I guess that we also get effects from the fact that each pixel sensor is basically in a well, and the smaller the pixel becomes, the harder it becomes for a photon to hit the sensor, rather than the well wall. I never hear this discussed either
It's not popular because you can't get a good library for free.
Most other formats are 'good enough', so why work with something new?
jpeg2000 is SLOW too. Even on high-end machines, it feels like jpg on a 386. It is impressive though. I have a highres picture I took which I took with a friends EOS Digital Rebel, I compressed with with jpeg2000 to under 200K and then visually compared them zoomed in. Was amazing, there were few noticable differences even when zoomed way in. (obviously wasn't using lossless option).
I'm sure there is some reasoning behing NASA's decision but that article doesn't say what it is!
But the funny thing is that NASA don't even have decent software for tiling those images so they have seams everywhere (and I don't just mean from the color variance).
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
That would be the correct usage of the mega prefix. If you check the definition of SI prefixes (which mega is one of) you will find they are all defined in terms of base 10, and no other base. Kilo is defined as 10^3, mega as 10^6 and so on. Thus a mega-anything is 1,000,000 of that thing by definition.
However, computer people hijacked the prefixes and started using them incorrectly. Since computers are base 2, base 10 numbers don't divide down nicely. 1,000,000 isn't remotely near a nice round number in base 2. So they took the SI prefixes and used them to indicate base 2 numbers. Kilo was used to mean 2^10, mega 2^20 and so on.
Well this is an incorrect usage, and one seen ONLY in computers. Everything else, it is base 10. If I say I have a kilogram of something I mean 1000 grams. Likewise with calories, metres, whatever.
Using color filters for high quality digital color photography is an old technology (and even older for analog). Its obvious limitation is that the subject has to be still.
Bigger pixels at lower resolution are not necessarily a good tradeoff: you can do almost as well in terms of noise and sensitivity by using more smaller sensors and performing the averaging in software.
Compositing lots of low resolution images into a single high resolution image is also completely standard: you can get both free and commercial software to do it.
Altogether, I suspect that if you take something like the new Sony 8Mpixel camera and take raw pictures with it, and reduce it to 1024x768 using good software, you are going to be pretty close to the measured quality and sensitivity of Spirit's sensor (in practice, you'll see little or no difference under normal circumstances, however). Then, you can use compositing software to composit multiple images for panoramas.
The Spirit tradeoffs make sense for a Mars rover, also taking into account power and weight requirements, but they do not result in a level of picture quality that you couldn't achieve with the digital cameras you can buy at the local store.
For lots more info on the Pancam, other instruments on the rovers, and tons more history, news, status updates, video, 3d photos, and more, check out:
(AXCH) 2004 Mars Exploration Rovers - News, Status, Technical Info, History.
It varies depending on whether it's transmitting to Earth or to Mars orbit and possibly varies by some other factors, but it's slower than a cheap DSL line and often slower than a 56k modem. I think the highest number I ever saw was around 152 kbits/second.
Tim
Omnia vestra castrorum habetur nobis.
The article is clueless technically. The panorama cam takes hundreds of 1 megapixel images and stitches them together to produce the panoramas that have been published on the web.
i t_ p011.html
Anyone can acheive a similar effect with their digital camera by taking enough pictures and stitching them together with software.
To get an idea of what the raw ccd images look like from the panoramic cam, check out the raw image gallery from JPL:
http://marsrovers.jpl.nasa.gov/gallery/all/spir
Got this as an email the other day on my University of Minnesota account...it talks about the compression used. Haven't read up on it, though.
"The Mars Exploration Rover (MER) is currently landing a pair of rovers on Mars (one landed last week and the other will be landing soon).
Well over half of the bits transmitted from the rovers will consist of compressed image data gathered from the unprecedented nine cameras
on-board each rover. This compression is based on the ICER and the LOCO [1] image compression technologies. LOCO was developed by Dr. Marcelo Weinberger and Dr. Gadiel Seroussi from Hewlett-Packard Laboratories and Prof. Sapiro from the Electrical and Computer Engineering Department (while he was at the HP Labs before joining the University).
The JPL/NASA hardware implementation of LOCO on-board the rovers is used when maximum geometric and radiometric fidelity is required. The LOCO technology, patented by Sapiro, Seroussi, and Weinberger at Hewlett-Packard Laboratories, is also the core of the international standard JPEG-LS for
the lossless and near-lossless compression of still images."
[1] M. J. Weinberger, G, Seroussi, and G. Sapiro, ``The LOCO-I lossless image compression algorithm: Principles and standardization into JPEG-LS,'' IEEE Trans. Image Processing 9, pp. 1309-1324, 2000.)