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`JAN FEB JUN
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`26
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`1999 2000 2001
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`TerraServer Site Story
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`3 captures
`26 Feb 2000 - 14 Sep 2000
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`TerraServer Scale
`TerraServer Resolution Examples
`
`The three images above are the same size but contain varying amounts of land area and detail. The left
`image shows a large area of San Francisco with very little detail. The middle image shows less area and
`more detail. The right image shows a very small area of the Bay Bridge with a lot of detail. The contrast
`between land area and image detail is known as the image's resolution. The left image is considered to be
`a "lower resolution image". Each pixel covers 32 meters on a side, whereas the right most "high
`resolution image" covers 1 meter per pixel.
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`The resolution, or ground area, of a satellite or aerial image is measured by the amount of area covered
`by each pixel in the digital image. For example, if you are viewing a TerraServer image at 16 meters,
`each side of a pixel or dot represents the length of 16 meters on the ground. (By the way, if you click the
`meter "Detail" line on the image display page, you will be able to see information on the size and
`resolution of the image you are viewing.)
`
`To visualize the resolution levels of an image, imagine a pyramid. TerraServer supports seven levels for
`each image pyramid, ranging from 1-meter resolution (showing more detail) to 64-meter resolution
`(showing more ground area). The source imagery is up or down sampled (added to or substracted from)
`as necessary to an appropriate Microsoft TerraServer resolution. Sampling basically means drawing a
`"sample" from a tile and adding or substracting to it to get different levels of resolution.
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`To compute all these resolutions, TerraServer uses its TerraScale program. TerraScale is the second load
`program in the Load Management Schema used to import images into TerraServer's imagery database. It
`re-samples the tiles created by TerraCutter to create the lower resolution tiles in the image pyramid. To
`create a lower resolution tile, TerraScale takes four tiles from the next higher resolution and averages
`four pixel values into one pixel value. TerraScale repeats this process at every resolution level until it tiles
`the lowest resolution tile for a given image.
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`https://web-beta.archive.org/web/20000226014211/http://terraserver.microsoft.com/terra_story_scale.asp[4/26/2017 3:01:59 PM]
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`Microsoft, Ex. 1028
`Microsoft v. Bradium, IPR2016-01897
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`TerraServer Site Story
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`The diagram above depicts how the highest resolution tiles loaded by TerraCutter contribute to the pixels
`at lower resolution. We refer to the tiles loaded by the TerraCutter program as the "base scale" or "base
`tiles".
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`The number of lower resolution tile levels created by the TerraScale program is theme dependent. The
`USGS DOQ base scale is 1 meter. The SPIN-2 base scale is 2 meters. TerraScale creates 2-meter
`resolution through 64-meter resolution - a total of seven levels.
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`USGS DRG data is a special case. Original DRG input images are available at 2.5-meter resolution, 10-
`meter resolution, and 25-meter resolution. TerraCutter re-samples the 2.5-meter resolution image into
`the 2-meter tile table, the 10-meter input image into the 16-meter tile table and the 25-meter image into
`the 64-meter tile table. TerraScale re-samples the 2-meter tiles into the 4- and 8-meter tables. The 16-
`meter tiles are re-sampled into to the 32-meter table. The 64-meter tiles are re-sampled into the 128-
`meter table.
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`The TerraScale program takes into account the ever-changing landscape in the base tile table. It handles
`the case where lower resolution tiles must be padded with blank space because not all of the lower
`resolution tiles yet exist. It determines that a lower resolution tile must be re-sampled based on the insert
`dates maintained in each tile table.
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`
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`Each time the TerraCutter program completes an input file found in the source path, it inserts a row into
`the ScaleJob table. This is the signal to the TerraScale program that a block of image tiles is ready to
`have its image pyramid created. The TerraScale program updates the ScaleJob table with its progress
`information, and again a set of Active Server Pages are used to monitor the progress of the image
`pyramid creation.
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`The TerraScale program continuously scans the ScaleJob table for new work to do. If it finds a row with a
`"job queued" status for the theme and zone it is assigned to, then it reads the job characteristics and
`updates the ScaleJob row to indicate that the TerraScale program is handling the job.
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`The ScaleJob fields identify the minimum and maximum X and Y values inserted into the base tile table
`by the TerraCutter for a single SceneID value. TerraScale computes the range of X and Y values for the
`lowest resolution scale that it must generate for the theme type. This constrains the size of the image
`pyramid the TerraScale program will attempt to create during this ScaleJob run.
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`TerraScale begins a loop to create the tiles at the lowest resolution. This is the top of the image pyramid.
`It fetches the current tile's insert date and image pixels. Then it fetches the four tiles and insert dates at
`the next higher resolution level. It recurses down the image pyramid (higher resolution levels) until it
`fetches the four base tiles and the insert date. If any of the insert dates along the way are after the insert
`date found in the ScaleJob table, the TerraScale program will resample the imagery along the line of
`descent. If the dates of the higher resolution images are on or before the insert date found in the
`ScaleJob, the TerraScale can skip the re-sample process.
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`https://web-beta.archive.org/web/20000226014211/http://terraserver.microsoft.com/terra_story_scale.asp[4/26/2017 3:01:59 PM]
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`TerraServer Site Story
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`The TerraScale program continues to walk up-and-down the image pyramid underneath the lowest
`resolution tile it is generating. It finally completes and moves on to the next X,Y value to process for the
`ScaleJob and repeats the process.
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`TerraScale is told which resolution levels are to represent the image pyramid in the search system. As a
`last step in building an image pyramid for a particular low resolution X,Y value, TerraScale inserts the
`appropriate rows into the ImagePlace and ImageSearch tables. A tile is not visible in the TerraServer
`application until a row is inserted into these two tables.
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`When all the X, Y pairs are completed for the lowest resolution tiles, TerraScale updates the ScaleJob to
`indicate that it has completed the job.
`
`Both TerraCutter and TerraScale continously do their jobs in the background while you browse imagery on
`TerraServer. The table design and load program insertion order ensures that all the required meta data
`and imagery is in place prior to new imagery being made visible to the web application.
`
`Now the image files have been received from TerraServer's data sources, loaded into the database, and
`"sliced and diced" into millions of image tiles. How does TerraServer access all these stored image tiles to
`display an image on the screen as you browse? Move on to the next section, "TerraServer Interface", to
`find out what happens when you click an image link.
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`https://web-beta.archive.org/web/20000226014211/http://terraserver.microsoft.com/terra_story_scale.asp[4/26/2017 3:01:59 PM]
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