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TerraServer Web Site

Access 15TB of mosaic'd aerial imagery & 65,000 topographical maps online. No GIS expertise needed. Discover image pyramids, scenes, and themes. TerraServer offers easy, scalable, and programmable access to geospatial data.

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TerraServer Web Site

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  1. TerraServer Web Site

  2. Digital OrthoQuads 15 TB, 280,000 files uncompressed Digitized aerial imagery 96% coverage conterminous US 1 meter resolution < 15 years old Digital Raster Graphics 1 TB compressed TIFF, 65,000 files Scanned topo maps 100% U.S. coverage 1:24,000, 1:100,000 and 1:250,000 scale maps Maps vary in age USGS Image Data • Urban Area • 1 foot resolution • Natural Color • 133 major U.S. cities • 30 available 2004 • 2001 or later • Produced by NIMA for Homeland Security

  3. Image Coverage • 100% U.S., Topo Maps (light green)2m to 1024m resolution • 96% 48 Conterminous States, (dark green)Ortho Imagery, 1m to 1024m resolution

  4. What is TerraServer? • A remote sensing image store • Images are “shredded” into small, uniform sized tiles • Multiple input images are mosaic’d into a single “scene” • An HTML based web application • Navigate by point-n-click, gazetteer or coordinates • Pan-n-zoom by clicking on simple navigation buttons • (No fancy java, activex, flash controls) • An XML based web service • Meta-data and tiles accessible via W3C web service API • An OpenGIS compliant Web Map Server • Tiles merged into single “map” image • Re-projection from UTM to “geographic” supported

  5. Public: Access to remote sensing data with no GIS expertise required Ubiquitous: No special hw/sw required by client Delivery: All OnLine/Internet Based, no tape or CD distribution Simple: Designed to be used by a “6th grade geography student” Scale-up: creating multi-TB PC Server Availability: Test software and ops in a 24x7 situation Lights out: all operations & maintenance occurs remotely Easy: Minimal ops and dev staff Programmable: Meta & Imagery data accessible as a “web service” Design Objectives User/App Goals Technology Goals

  6. TerraServer Concepts • Tile: An “addressable” chunk extracted from a “Theme” • Theme: An image asset/data-set in a single projection “class”, i.e. UTM NAD83, Geographic, etc. • Scene: A grouping of related Tiles that can be shown together as a “seamless mosaic” without any image processing tricks, e.g. a UTM zone, a single satellite swath, etc. • Scale: An ID# assigned to the ground resolution of pixels in a Tile. • Image Pyramid: The set of Scales a Theme’s Tiles rendered in and stored, e.g. DOQ scale 10 .. 21 (1m/pix to 2048 m/pix)

  7. 10,000,000 UTM Zone 0 0 500,000 1,000,000 More Concepts • Scale System: Begins at 10 for 1 meter/pix resolution, +/- 1 for each 2x resolution, i.e. 11 = 2m, 12 = 4m, 9 = .5m • Grid System: X,Y identifies Tile location within a scene. Positive, Scale based integers starting from lower left corner of the Scene • Tile Shape: Square. • Tile Size: 200 is 200x200 pixels 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0 199 0 199 0 0 1 2 3 4 5 6 7 8 9 10 1112 13141516 171819 2021 22

  8. Why 200 x 200 Pixel Tiles • Fit different size monitors (using html tables) • 2x1 = 800 x 600 monitors • 3x2 = 1024 x 768 monitors • 4x3 = 1280 x 1024 and larger monitors • Progressive display over slow speed lines • Tiles average < 10kb • Panning takes advantage of browser cache • Maintains image quality • Without storing uncompressed full res imagery • USGS DOQ imagery overlaps by 300 pixels • USGS DOQ images arrive in random order

  9. KVM / IP TerraServer Hardware • Storage Bricks • Commodity servers” • 4 TB raw / 2 TB Raid1 SATA storage • Dual 2 GHz + 4GB RAM • 3 Bricks = TerraServer data • Data partitioned • Moving to Yukon • Working on low TCO auto-manage • Low Cost Availability Pair & Spare • RAID1 Mirroring • Mirrored Bunches (Yukon log ship?) • Spare Brick • Web Application • Load balances mirrors • Uses surviving database on failure

  10. KVM / IP The TerraServer Storyhttp://terraserver-usa.com/image.aspx?t=4&s=9&x=5655&y=52766&z=10&w=2 • 1997: 8 DEC Alpha, • 8GB, • 480x18GB disks • ~1 TB • 2000: 4x8 Pentium3 600Mhz, • 16GB ram • 540 36GB FC SCSI disks • FC SAN • ~18TB • 2004: 7x2 Xeon • ~100 250 GB SATA disks • 28 TB • 70k$ • NO TAPE • Next: • Geo-Plex

  11. Soon: The Virtual Observatory • Many new surveys are coming • SDSS is a dry run for the next ones • LSST will be 5TB/night • All the data will be on the Internet • ftp, web services… • Data and applications will be associated with the projects • Distributed world wide, cross-indexed • Federation is a must • Will be the best telescope in the world • World Wide Telescope • Finds the “needle in the haystack” • Successful demonstrations NOW!

  12. SkyServer, Virtual Observatory • The Problem: • Bring Astronomy data online • Integrate the online archives • Our/my focus • Database and architecture help • Algorithms • Implementation • Connect to CS community

  13. daCosta etal 1995 deLapparent, Geller and Huchra 1986 Gregory and Thompson 1978 The Cosmic Genome Project The SDSS will create the ultimate mapof the Universe, with much more detailthan any other measurement before

  14. Features of the SDSS 2.5m telescope, located at Apache Point, NM 3 degree field of view. Zero distortion focal plane. Two surveys in one: Photometric survey in 5 bands. Spectroscopic redshift survey. Huge CCD Mosaic 30 CCDs 2K x 2K (imaging) 22 CCDs 2K x 400 (astrometry) Two high resolution spectrographs 2 x 320 fibers, with 3 arcsec diameter. R=2000 resolution with 4096 pixels. Spectral coverage from 3900Å to 9200Å. Automated data reduction Over 70 man-years of development effort. (Fermilab + collaboration scientists) Very high data volume Expect over 20 TB of raw data. About 1 TB processed catalogs. Data made available to the public.

  15. The Telescope Special 2.5m telescope 3 degree field of view Zero distortion focal plane Wind screen moved separately

  16. 1/8 inch (3 mm) 0.4 arc-sec One Mile(1.7 km) How Good is the Telescope? • SDSS telescope has 120 Million CCD pixels: • 55 second photometric exposure. • 8 MB/sec data rate. • 0.4 arc-sec pixel size. • Also Spectroscopic Survey of 1 million obj. • As good as the atmosphere • Seeing 20 nights per year.

  17. The Photometric Survey Northern Galactic Cap 5 broad-band filters ( u', g', r', i', z’ ) limiting magnitudes (22.3, 23.3, 23.1, 22.3, 20.8) drift scan of 10,000 square degrees 55 sec exposure time 40 TB raw imaging data -> pipeline -> 100,000,000 galaxies 50,000,000 stars calibration to 2% at r'=19.8 only done in the best seeing (20 nights/yr) pixel size is 0.4 arcsec, astrometric precision is 60 milliarcsec Southern Galactic Cap multiple scans (> 30 times) of the same stripe Continuous data rate of 8 Mbytes/sec

  18. The Spectroscopic Survey Measure redshifts of objects  distance SDSS Redshift Survey: 1 million galaxies 100,000 quasars 100,000 stars Two high throughput spectrographs spectral range 3900-9200 Å. 640 spectra simultaneously. R=2000 resolution. Automated reduction of spectra Very high sampling density and completeness Objects in other catalogs also targeted

  19. The Mosaic Camera

  20. Photometric Calibrations • The SDSS will create a new photometric system: • u' g' r' i' z' • Primary standards: observed with the USNO 40-inch telescope in Flagstaff • Secondary standards:observed with the SDSS 20-inch telescope at Apache Point – calibrating the SDSS imaging data

  21. The Spectrographs Two double spectrographs very high throughput two 2048x2048 CCD detectors mounted on the telescope light fed through slithead

  22. The Fiber Feed System Galaxy images are captured by optical fibers lined up on the spectrograph slit Manually plugged during the day into Al plugboards 640 fibers in each bundle The largest fiber system today

  23. Spectrograph Status Spectrographs: Laboratory observations of solar spectrum First astronomical observations March 1999

  24. First Light Images Telescope: First light May 9th 1998 Equatorial scans

  25. The First Stripes Camera: 5 color imaging of >100 square degrees Multiple scans across the same fields Photometric limits as expected

  26. NGC 2068

  27. UGC 3214

  28. NGC 6070

  29. The First Quasars Three of the four highest redshift quasars have been found in the first SDSS test data !

  30. The Stripes • 25 stripes over the SDSS area, covering about 2800 square degrees • Resolution: 0.4 arc seconds. • About 20% lost due to bad seeing • Masks: seeing, bright stars, etc. • Images generated from query by web service

  31. The Masks • A Stripe - masks • Masks are derived from the database • Search and intersect extended objects with boundaries

  32. Major Changes in Astronomy • Visual Observation --> Photographic Plates--> Massive Scans of the Sky collecting Terabytes. • A PracticeScan of the SDSS Telescope Discovered 3 of the 4 most Distant Quasars! • SDSS plus other Surveys will yield a Digital Sky • Telescope Quality Data available Online. • Spatial Data Mining will find new objects. • New research areas - Study Density Fluctuations.

  33. Next Generation • 50TB/night • First light 2010 • Survey sky every 2 weeks • Survey time domain • Lots of activity outside the optical domain.

  34. Moving Data Bricks • The cheapest and fastest way to move a Terabyte cross country is sneakernet.24 hours = 4 MB/s50$ shipping vs 1,000$ wan cost.

  35. OC192 = 9.9 Gbps Giga Byte Per Second File Mover • CERN to Pasadena • Windows TCP/IP stack improvements • Opteron demo • Disk-to-Disk at 550MBps now (~2 TB/Hour) • What we learned: • Linux tcp stack is good/better at high perfwe are catching up. • NTFS is better than various Linux FS • Near the PCI-X limit • Good way to engage the community. • GOAL: 1GBps disk-to-disk. PCI -X limit tcp limit

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