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India Launches World's First Stereo Imaging Satellite

Posted by CmdrTaco on from the zombies-look-so-real-in-three-dee dept.

sgups writes "India will tomorrow inaugurate a new launch pad at its Satish Dhawan space port near Chennai, on the south-east coast, by putting the world's first stereographic mapping satellite into orbit. The most innovative feature of the 1.6-tonne Cartosat-1 is its pair of cameras, which will give stereo images of the earth's surface that can distinguish features down to 2.5 metres across. They will directly generate three-dimensional maps that have until now been achievable only indirectly, by combining data from a large number of satellite passes over the same place. "Such a stereographic imaging system does not exist in the civil sector anywhere else," says Mr Nair, chairman of the Bangalore-based Indian Space Research Organisation (Isro). "It will give information about heights that will be very useful in applications such as planning power lines." Cartosat-1 will join what is already the world's largest cluster of non-military remote sensing satellites. Six Indian spacecraft are already observing the earth with a wide range of instruments."

18 of 339 comments (clear)

  1. Imagine the Possibilities by ackthpt · · Score: 2, Interesting
    3D from Space with 2.5m resolution. You could...

    • See your house from anywhere!
    • Get cool 3D images of Grand Canyon, Yosemite, Everest, Uluru, etc.
    • Map for video game use
    • See who keeps sneaking their $&^%@ trash into your can.
    • See volcanoes, jets taking off/landing, tsunamis, etc.
    • Conduct industrial/military espionage at an all new level!
    • Watch W. squirm, trying to talk the indians how they should run it, what they should and shouldn't be looking at, etc. (probably done behind close doors, all hush-hush, though.)
    • Maybe see a space shuttle launching! (I know that would be über-cool!)
    • Be bored stiff after 20 minutes, thanks your years of ADD training by TV and the internet.

    Six Indian spacecraft are already observing the earth with a wide range of instruments."

    Though probably none are currently tracking CowboyNeal.

    --

    A feeling of having made the same mistake before: Deja Foobar
    1. Re:Imagine the Possibilities by iocat · · Score: 2, Interesting
      This is nearly pointless. 3D stereo images for remote sensing are usually taken by PLANES so you can get WAY better imaging quality than 2.5m you get from a satellite.

      And, for maybe the first time ever, I actually know what I am talking about in a slashdot post, because I studied this crap in college.

      --

      Dude, I think I can see my house from here.

  2. What? How far apart... by robslimo · · Score: 3, Interesting

    do the cameras have to be to get a proper parallax?

  3. Heights? by Neil+Blender · · Score: 3, Interesting

    Uh, can't they already determine heights to high degree of accuracy with GPS or other radio wave methods? How would a picture be more accurate?

    1. Re:Heights? by NanoGator · · Score: 2, Interesting

      "Uh, can't they already determine heights to high degree of accuracy with GPS or other radio wave methods?"

      Yes, but they're not passive. You either have to send an energy wave down or somebody holding a GPS unit. This satellite could get that data passively.

      "How would a picture be more accurate?"

      I didn't RTFA so I don't know the context of the word 'Accurate'. I can tell you, though, that I've seen stereoscopic images taken from airplanes travelling over .. uh.. bombing targets. The imagery was amazing. You could see things like guard towers etc that you couldn't make out so easily with only one photo.

      Also, concievably, they could take color images. There's no way you could get color data via the other methods you mentioned. If you're looking down over a city, for example, a stereo color image will tell you a LOT more than anything radar or GPS could do. In the sense that the data is more useful, yes, it's very accurate.

      --
      "Derp de derp."
    2. Re:Heights? by atom_pheer · · Score: 2, Interesting
      Uh, can't they already determine heights to high degree of accuracy with GPS or other radio wave methods? How would a picture be more accurate?


      Yes, with accurate clocks, it is possible to determine the location of observer in the space, relative to satellites, quite accurately.
      However, for mapping this method is quite inpractical:
      To distinguish elevation of every 2.5 * 2.5 meter spot on earth, one would need to move the receiver unit through every spot of that size.
      The Earth's surface area is about 4 * pi * (6371 km)^2 = 5.101 * 10^14 m^2. The area of 2.5 * 2.5 m is 6.25 m^2. One would need to move GPS unit to 5.101 * 10^14 / 6,25 = 8.161^13 locations. Good exercise?
      On the other hand, something like radio echograph would need energy to get the signal through atmosphere, to ground, and back to the satellite, and therefore is quite impractical for heavy mapping sessions.
  4. I don't get by JohnFluxx · · Score: 3, Interesting

    I don't get. If it's not a geosync, then it's going to be moving, so they could just use 2 images from a few seconds apart to get the required images. No?

    1. Re:I don't get by robslimo · · Score: 2, Interesting

      It has been done (pdf) with images from Space Imaging's sats, so I'm still a bit in the dark as to what 2 cameras buys the Indians (there must be something, eh?).

  5. Geologic Mapping by tectomorph · · Score: 2, Interesting

    Stereoscopic imagery is great for mapping geology. Most stereo photos are not shot at a small enough scale to do regional mapping so this could be wonderful. Hopefully the data will be easily obtainable and the coverage will be suitable to do broad-scale work.

  6. Why two cameras needed? by Jerf · · Score: 5, Interesting

    I'm going to assume the satellite designers knew what they were doing and there is some good reason for this.

    That said, given the resolution with which we know the position of a given satellite, and the low resolution of the source image in this case, what advantage does using two cameras give you, vs. taking one camera and snapping two pictures in quick succession?

    Maybe they can't be snapped quickly enough? But then, you'd think the larger parallax would be helpful, not harmful.) I know consumer cameras have the basic tech now to take a snapshot of the CCD state and process it later, that tech ought to scale right with the CCD resolution, whatever it is.

    Maybe this is so you can choose the parallax direction, instead of the orbit forcing your choice? Does the image processing need the parallax to show up in some particular direction relative to the light source to work?

    Honest questions; knowledgeable answers appreciated. (As you can see, I can talk out of my ass too :-), I'm looking for something a little more informed.)

    1. Re:Why two cameras needed? by Kainaw · · Score: 2, Interesting

      Why two cameras needed?

      I didn't have anything to do with the design of this, but I have to assume that two cameras are necessary because you'd have to tilt the camera otherwise. Normally, a satcam is pointed straight down. If you get two images a few meters apart, you can't derive much z-axis data from them. With the cameras tilted so that they converge at the approximate height of the sat, you can derive z-axis information and work out the height of items on the ground.

      Of course, you don't *need* two cameras. As I said, you could tilt the camera and take a snapshot of one spot from two angles. A much neater thing to do (in my opinion), would be to put a tilted camera on the outside of spinning ring. Then, try to keep the sat in one position as you take a 360 degree spin around something of interest on the ground. I bet 2 cameras is much cheaper though.

      --
      The previous comment is purposely vague and generalized, but all of the facts are completely true.
    2. Re:Why two cameras needed? by UnknowingFool · · Score: 4, Interesting
      what advantage does using two cameras give you, vs. taking one camera and snapping two pictures in quick succession?

      For a parallel example, try to take a picture of the ground from a moving vehicle at 10mph. To get a decently clear and detailed picture, your film speed would have to be high. Now try to get a stereographic image of an ant hill from overhead while moving from a vehicle at 10mph. With one camera you'd have to take fast pictures and move the camera angle without motion blur. As an alternative you could take one picture, change the angle, and pass over the ant hill a second time.

      Applying those techniques to satellite imagery doesn't work well. The satellite can't rotate fast enough considering how fast it is passing over a target area. Using 2 passes does work but that unfortunately expends fuel to change the position of the satellite every time. So the lifetime of the satellite is sharply reduced unless it is serviced in space. Rarely are satellites ever serviced. Those that are serviced (Hubble, ISS, etc) have to be extremely important.

      --
      Well, there's spam egg sausage and spam, that's not got much spam in it.
  7. Not the distance between the cameras by Langolier · · Score: 5, Interesting
    Though it does not say this in the article, it is not the distance between the two cameras on the satellite that produces 3D imagery. The cameras will be pointed in slightly different directions, so that the image taken by one camera at time t will be paired with the image taken by the second camera at time t+x, where the satellite has traveled probably tens of miles in time x. The second camera is pointed slightly "backwards", so that it takes pictures of the same area that the first camera was shooting x seconds ago.

    This is just supposition, based on the fact that two cameras on a satellite would not be far enough apart to generate parallax.

    --
    Share. Until it becomes uncomfortable. Or at least a little.
    1. Re:Not the distance between the cameras by Apotsy · · Score: 2, Interesting

      If that's the case, why are two cameras necessary? I supposed it could result in more speed and flexibility, but it sounds as though the same thing can be done with careful aiming and timing using just one camera.

      --
      Free Hans!
  8. Three Corner Sat by eggbert.net · · Score: 4, Interesting

    Over the summer and last semester I worked in a nano-satellite lab at ASU. The most recent satellite of ours that was launched was Three Corner Sat and one of its primary mission objective was sterio imaging.

    http://threecornersat.jpl.nasa.gov/
    http://nasa.asu.edu/
    https://spacegrant.colorado.edu/tiki-index.php?pag e=3CS

    Unfortunately, the two of our satellites that got launched were released at 50,000 km instead of 100,000 km so they burnt up before they could power up.

    http://www.spacetoday.net/Summary/2737

    --
    -- James
  9. Somebody is conflating ... by Ancient_Hacker · · Score: 2, Interesting

    There's probably TWO cameras, one for visible light, one for infrared. Not two cameras for binocular vision. The two "eyes" would be too close together for any usable stereoscopic effect.

  10. All this... by prisoner-of-enigma · · Score: 2, Interesting

    Plenty of orbiting satellites up there. What's amazing is this comes from a country with an average literacy rate of 52% (compared to 97% for the U.S.).

    48% of their citizens can't read or write, but they're funding a space program to the equivalent of a few billion U.S. dollars. Amazing. I can only imagine what taxes must be like in India to pay for something so expensive when the per capita income is so low.

    --
    In the end they will lay their freedom at our feet and say to us, Make us your slaves, but feed us. - Fyodor Dostoyevsky
  11. Re:power lines? Riiiight. by Lord+Omlette · · Score: 3, Interesting
    Like decades if not centuries of maps can't help there.
    There's a really good book called The Great Hedge of India that touches on this sort of thing. Basically, in India, everything moves around so much that maps are worthless after a couple of years.

    I'm not saying you're wrong about Pakistan though, just that you're wrong about archived maps of India...
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    [o]_O