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`⍰ About this capture
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`OCT NOV JAN
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`29
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`1998 1999 2001
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`TerraServer Site Story
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`16 captures
`29 Nov 1999 - 27 Jun 2004
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`TerraServer Story
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`The above images covers an area approximately 8 miles across and 5 miles from north to south. The
`complete picture was formed by processing over twenty 50-Megabyte files. This section of the Web site
`explains how these very large pictures were processed so that you can view them relatively quickly over
`the Internet using the average home PC.
`
`TerraServer's purpose is to provide viewers access to such vast amounts of data over slow speed
`telecommunication lines and simple computer designs such as PCs and web browsers. Historically, users
`were required to have high-end graphics workstations that had the CPU, memory, and graphics hardware
`capabilities to manipulate this data, as well as be close to where the data was stored. Even then, it was
`rare for systems to have access to much more than 50 to 100 gigabytes of image data at one time.
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`Our goal is to give our viewers access to "terabytes" of data (10 to 100 times more than normal access)
`while browsing the Internet from the comfort of their own homes. Instead of presenting images in their
`original large format, TerraServer divides these images into small tiles that can be retrieved over the
`Internet. The story that follows describes how TerraServer takes the images and cuts, inventories, and
`displays them on your computer.
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`Keeping in mind that the picture above had to be one huge picture to begin with, how does TerraServer
`take it apart and put it back together again to fit on your computer screen? An analogy is to imagine
`taking your 35m camera - with no wide-angle lens - to a large family gathering to take a group photo of
`everyone in attendance. Because there are too many people to fit in your camera's view finder, you would
`have to take several pictures in a panoramic-type view. When the film is developed, you would then take
`your scissors, trim the picture edges, and try to match and glue each panoramic photo into one big
`picture. You would also want to overlap the edges a bit in order to line up the pieces correctly as "one"
`scene. And it might not be a bad idea to number each individual piece so that you can easily recognize its
`place in the "whole" picture.
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`https://web-beta.archive.org/web/19991129051006/http://terraserver.microsoft.com/terra_story_images.asp[4/26/2017 2:56:43 PM]
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`Microsoft, Ex. 1026
`Microsoft v. Bradium, IPR2016-01897
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`TerraServer Site Story
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`TerraServer basically does just that with its image editing, although our process is a bit more
`complicated, of course.
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`An original Russian satellite image from SPIN-2, for example, is a 40-kilometer by 160-kilometer sized
`photographic swath of a particular area of earth. These pieces of film are too large to scan at once, so
`they are scanned and overlapped as four separate 40-kilometer square images. From Russia, the four 40
`X 40-kilometer sections are sent to Aerial Images/SPIN-2 in North Carolina where they are again
`quartered into 20-kilometer square images. Tapes containing these uncompressed 20 X 20-kilometer
`image files are then shipped to Microsoft for further processing and loading onto TerraServer.
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`The files Microsoft receives still contain too much data to be effectively downloaded over the Internet.
`Depending on the type of image - satellite or aerial photograph - a single image can range between 50 MB
`and 1,500 MB in size. The TerraServer team wrote an image processing program that takes several of
`these large input files at a time, computes the image's location on earth, and merges pixels from multiple
`files into one single photo. The merged images are then cut into smaller images and compressed in the
`JPEG file format so Web browsers can recognize them.
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`By the way, a pixel is the smallest visible unit within an image and represents a shade of color or
`grayscale at a a single location point on the image. An image pixel is similar in concept to a "dot" in "dots
`per inch" when explaining how a printer sprays ink on the printed page. A typical satellite image may be
`as large as 40,000 by 40,000 pixels, whereas a typical graphic on a Web page may be only 300 pixels by
`100 pixels.
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`TerraServer's input imagery is re-sampled to the nearest power of 2 from 1 meter per pixel. USGS
`imagery is 1 meter per pixel. SPIN-2 input imagery is 1.56 meters per pixel and resampled to 2 meters
`per pixel. Imagery is edited into 200-pixel by 200-pixel tiles at all resolutions.
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`Keeping track of all these pieces of imagery is not as difficult as it may seem. The tiles are organized in
`TerraServer's database table by theme, resolution, and location. Each tile can be identified by where it
`was cut from in the original image by being assigned a relative X and Y tile identifier by TerraServer's
`tiling program. The relative position depends on whether the imagery type is from the USGS or SPIN-2.
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`There are unique fields that identify every image tile that is processed into the TerraServer database.
`These fields are:
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`Theme - The image data stored on TerraServer comes from a variety of sources and vary in format,
`resolution, color, and projection system by data source. TerraServer indexes and names imagery by
`projection system, which is a mathematical system to transform or project earth onto a flat surface.
`It also indexs by the acquisition method (satellite or aerial or drawn) and source (USGS, SPIN-2).
`These category names are called "themes" in TerraServer. Thus, all aerial imagery we present from
`the USGS is one theme. All the SPIN-2 imagery is a second theme. USGS topographical maps are a
`third theme.
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`Scale - Scale is the resolution of the image, or the area of ground represented in the image.
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`https://web-beta.archive.org/web/19991129051006/http://terraserver.microsoft.com/terra_story_images.asp[4/26/2017 2:56:43 PM]
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`TerraServer Site Story
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`TerraServer offers seven levels of resolution for every image. Complete information on image
`resolution is provided in the section entitled "TerraServer Scale".
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`X - Marks the tile's relative position on the X-axis within the image's "scene". The relative position
`starts from 0 on the "left" side of the scene.
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`Y - Marks the tile's relative position on the Y-axis within the scene. The relative position starts from
`0 on the "bottom" of the scene.
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`A tile is uniquely indexed in a table by these X and Y tile identifiers. The X and Y integer values
`identify the tile's place within the whole scene of an image tile. X tiles are sequentially numbered
`left to right beginning with 0 across the scene. Y tiles are sequentially numbered bottom to top
`beginning with 0 across the scene. Within the Universal Transverse Mercator (UTM) projection
`system, the X,Y offset is computed from the UTM value of the bottom left pixel of the tile cut from
`the image.
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`SceneID - The SceneID is assigned to each tile to group the X and Y values that can be displayed
`together on a single Web page. For USGS UTM projection data-sets, the SceneID is the UTM zone
`assigned to the original image a tile's pixels were extracted from. For SPIN-2 data-sets, a unique
`SceneID is assigned for each scene loaded per theme.
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`These fields uniquely identify a tile row within the TerraServer HTML table and are part of almost every
`URL within the TerraServer web application. An image's URL is TerraServer's version of the number you
`would use to identify an individual piece of your family portrait. An image's URL is its unique name and
`pointer to where it belongs in the whole scheme of things. It contains the X and Y values, the Scene ID
`("1" for USGS, "2" for SPIN-2), the image date and size. The URL is the data in the "Address" window on
`Internet Explorer or the "Location" window on Netscape Navigator. It usually looks something like this:
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`http://terraserver.microsoft.com/image.asp?T=1&S;=10&X;=2342&Y;=10368&Z;=10&W;=1
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`For those of you familiar with GIS systems, the USGS X, Y, and Z values can be converted to their UTM
`equivalents by using the simple formulas below:
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`UTMX = X x TileSize x MetersPerPixel
`UTMY = Y x TileSize x MetersPerPixel
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`To get the UTM address of the lower left hand corner of the tile represented in the URL above, the
`formulas would read:
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`The "Z" field in the URL is the UTM zone. The Scale or "S" field indicates meters per pixel. The following
`table maps Scale value to Meters Per Pixel (MPP):
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`X = 2342 x 200 x 1
`Y = 10368 x 200 x 1
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`Scale MPP
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`10
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`11
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`12
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`13
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`14
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`15
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`16
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`17
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`1
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`2
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`4
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`8
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`16
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`32
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`64
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`128
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`In summary, the TerraServer database stores millions of small tiles extracted from one or more input
`images from the USGS and SPIN-2. Each tile is associated with a scene from an individual theme. Using
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`https://web-beta.archive.org/web/19991129051006/http://terraserver.microsoft.com/terra_story_images.asp[4/26/2017 2:56:43 PM]
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`TerraServer Site Story
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`the resolution, X, Y, and SceneID values, TerraServer can reconstruct any portion of an original image or
`scene.
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`Click the "Next" button to find out how TerraServer's loading and cutting processes actually work.
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`TerraServer Built by
`Microsoft Research
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`© 1998-1999 Microsoft Corporation. All rights reserved. Terms of use.
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