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ATTENTION:
Due to server overloading, client applications are strongly advised to use the existing tile datasets wherever possible, as described in the Tiled WMS or Google Earth KML support
Frequent and repetitive requests for non-cached, small WMS tiles require an excessive amount of server resources and will be blocked in order to
preserve server functionality. The OnEarth server is an experimental technology demonstrator and does not have enough resources to support these requests.
An alternative solution already exists in the form of tiled WMS
While sets of tiles with different sizes and alignment can be added when needed, for large datasets the duplication of storage, processing and data management resources is prohibitive.
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Daily Planet, a countinuously updating image of the earth, using scenes from MODIS TERRA
A new dataset built for this server, available from Dec 1st 2007 as a beta test. This mosaic is continuosly updated with images from MODIS TERRA, which has almost global daily coverage. This layer is the most current, near-global image of the earth available. The resolution is 250m per pixel in the middle of the swath, less on the edges. Visit the MODIS Website for more information.
New images are added on top of the old data, in the order in which they become available. In general, the latest images are between 6 and 24 hour old. The update process is automated, various errors might be visible. To produce this mosaic, 80GB per day of raw MODIS scenes are downloaded from the LAADS Web, processed using HDFLook into visual images in a global coordinate system and spliced into the current composite. Previous days are also available and can be access using the WMS time argument. Use the OnEarth_DailyPlanet.kml file to view this layer in Google Earth. A WorldKit interactive browser of this data is available here, in addition to the screen icons the arrow keys and the A and Z keys can be used to pan and zoom.
Daily Afternoon, a countinuously updating image of the earth, using scenes from MODIS AQUA
A dataset almost identical with the DailyPlanet, built from MODIS AQUA data. The AQUA satellite crosses the equatorial line on the day side of
the earth in the afternoon, around 2PM, while the TERRA satellite, the source of the DailyPlanet dataset, does so around 10AM.
WMS Global Mosaic, Blue Marble background
This is also the home site of the WMS Global Mosaic, a high resolution global image mosaic of the earth, produced from more than 8200 individual Landsat7 scenes. Each scene requires more than 500MB of storage, or about one standard CD. These images have been collected during 1999-2003. The highest resolution image has a ground relative resolution of 15 meters, or 50 foot. The mosaic contains all nine spectral bands of the Landsat7 ETM+ instrument. Together with the associated Web Map Service Server, the mosaic is known as the WMS Global Mosaic.
An FGDC metadata compliant record, with more information about this dataset is available here: Metadata Link
The base dataset can be downloaded from download site A mirror download site is available at Telascience
WMS The Web Map Service (WMS) server providing access to the WMS Global Mosaic and other datasets is accessed via this base URL: http://wms.jpl.nasa.gov/wms.cgi. The WMS server capabilities, an XML encapsulated document describing the datasets and the server are can be retrieved via a Capabilities Request
Clicking on an image or on a caption on this site will take you to an interactive WMS map browser. This browser has limited capabilities and is intended only to provide a funtional view of the capabilities of the map server itself. Once in the browse mode, you can click on the image to recenter the view or use the zoom bar at the top of the image to zoom. The distance left or right of the black/blue center marker controls the zoom in or out amount, up to four times the current level. The browser will let you zoom out more than a single earth width, which will generate an error, and zoom in past the level of detail of the data. Other WMS clients do exist, and they can provide more functionality than the WMS browser available on this site. worldKit can be used as a WMS client, recommended worldkit configuration entries for a number of layers from this server are provided where applicable.
Users of WorldWind or Punt should use the OnEarth.xml configuration file. Save a copy of the configuration file in the WorldWind/Config/Earth subdirectory, and use the layer manager to enable layers from this server. Four different styles of the WMS Global Mosaic are configured, together with the daily TERRA/AQUA MODIS mosaics.
WorldKit viewer: WMS Global Mosaic pseudocolor WMS Global Mosaic visual
The WMS Global Mosaic, a High Resolution, Global Coverage, Landsat 7 mosaic.
Other window sizes:
500x500
1000x1000
1200x600
Other available layers:
30m SRTM Reflectance Image
This is the radar reflectance image produced by the SRTM mission. It is an example of the best available snapshot of the surface of the earth, being the highest resolution image collected in the shortest ammount of time, with near-global 30m coverage collected during an 11-day Endeavour mission, in February of 2000.
A radar reflectance image has little in common with a visual image, depending mostly on the material and orientation of the object. Areas with low detail such as lakes and sand tend to have no reflection, and very steep terrain can obscure certain areas from the side look ing SRTM instrument, both fenomena generating voids in the SRTM reflectance image. Urban areas tend to have stronger reflectance. The banding artifacts still visible in the images are the result of the combination of data from multiple orbits or are intrinsic to the SRTM instrument.
Five basic bands are available as WMS styles, ss1, ss2, ss3 and ss4 being SRTM image subswath averages, the all style being an average of the four subswath composites. The default style presented above is derived from the all band, using an arbitrary color map to make more detail visible. The subswath composites also available via the WMS SLD band selection mechanism, band 0 correspoinding to ss1, 1 to ss2, 2 to ss3, 3 to ss4 and 5 to all.
Due to hardware failures and insufficient resources, starting with March 12th 2008, the MODIS subset composites are no longer updated. This includes the visual, pseudocolor and NDVI, for both TERRA and AQUA MODIS. The archive is still available.
WorldKit viewer: MODIS aqua composite MODIS terra composite
Composite of data collected yesterday by the MODIS/Terra. Updated daily.
Composite of data collected yesterday by the MODIS/Aqua. Updated daily.
The two MODIS visual color composites are built on this site daily from high level Near-real-time Subsets
produced by the MODIS Rapid Response System.
The available subsets are being downloaded and combined in a single composite, at a uniform resolution of 8 arc-second per pixel or about 250m per pixel. The source images and the mosaics themselves are JPEG compressed. Some compression artifacts will be present in the composite, requesting PNG formated images will not produce better quality images
These daily composites are being archived and are available from this server using the WMS time argument. Available mosaics start on 2004-12-25. New mosaics, for the previous day becomes available around 10AM GMT, first TERRA then AQUA, the exact time of the refresh depending on the ammount of data to be processed that day. The two static jpeg images above are updated when the composites become available. A request for a non-existing day, including current and future days, will generate a black image
If the two images above are black, a likely cause is the lack of recent data from the MODIS Rapid Response System.
In addition to the visual composites above, for both TERRA MODIS and AQUA MODIS, two alternate color mappings are available, the 721 band to RGB mapping and the Normalized Difference Vegetation Index (NDVI).
Daily TERRA 721 and
Daily AQUA 721
Daily TERRA NDVI and
Daily AQUA NDVI
The 721 mapping is used to identify recently burnt areas, which appear red or brown in this mapping. Since it has increased water contrast compared with the visual images, it can be used to identify flooded areas. The NDVI is strongly correlated with the density and state of vegetation, and can be used to monitor the state of the crops. These mosaics are updated daily right after the visual composites. The image above is only updated once all four composites are complete.
More information about the various mapping is available from the Rapid Response System FAQ
There are two operational MODIS instruments, on two satellites named Aqua and Terra. More information about the MODIS instrument and data is available at the MODIS site.
Blue Marble, a 1Km resolution global world image derived from the MODIS instrument of the TERRA satellite
WorldKit viewer: Blue Marble Next Generation
Blue Marble Next Generation, A MODIS-derived 500m true color earth dataset showing seasonal dynamics. This version of the BMNG was updated in June 2007.
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan_nb
Feb_nb
Mar_nb
Apr_nb
May_nb
Jun_nb
Jul_nb
Aug_nb
Sep_nb
Oct_nb
Nov_nb
Dec_nb
Jan_ns
Feb_ns
Mar_ns
Apr_ns
May_ns
Jun_ns
Jul_ns
Aug_ns
Sep_ns
Oct_ns
Nov_ns
Dec_ns
There are thirtysix styles associated with the Blue Marble Next Generation layer, three styles for each month of the year. The individual links below the image are shortcuts to a browser using these styles. The styles with names ending in _ns have no shading on land or ocean, while the ones ending in _nb have no ocean bottom shading. The styles named simply after the month they represent have both land topography and ocean bathymetry shading.
A SRTM derived, 90m world elevation model
The National Elevation Dataset (NED), at 30m resolution
The NED source data is full precision floating point real numbers. It is possible to retrieve those values by requesting the real or feet_real styles and tiff or geotiff format.
In addition, the "short_int" styles described below work on this layer, when using a tiff, geotiff or PNG format.
Another continental US, 90m elevation model
The default styles for the elevation layers are a version of the elevation maps scaled to 8 bit. The full elevation values can be retrieved from this server by requesting the short_int or feet_short_int styles in combination with the image/png image/geotiff or image/tiff value for the format argument. The result of such a request will be an image where the signed short integer values contained in the image file for each pixel are the elevation of the respective point on the map, in either meters or feet. The base data is in meters. The us_ned layer base data is floating point real numbers in meters, data which can be retried in tiff or geotiff format when using the real or feet_real as styles.
All the datasets that exist on this server are documented for WMS clients in an XML formated Capabilities file.
This file contains information about the layers, which correspond to datasets, and the styles associated with them.
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| WMS Global Mosaic use examples: |
The main dataset is the WMS Global Mosaic, a mosaic of Landsat7 imagery over the whole earth.
This image shows the default color, obtained by using two infrared bands and
one visual for color and the panchromatic, high resolution band for luminance.
This is known as the 542 color, pansharpened color scheme, or pansharpened pseudocolor.
The area selected here is the Mammoth Mountain, California. A lot of detail is
visible in the image, including ski slopes, portions of the golf course, and the city
of Mammoth Lakes. Click on the image to start the interactive browser.
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There are two layers associated with the Global Mosaic data, the main difference between them
being pansharpening. Pansharpening is a generic term describing the use of the
higher resolution panchromatic band (15 meters per pixel) to increase the level of
detail visible in the lower resolution bands. Since this type of procedure is mostly
associated with the Landsat 7 instrument, it is not handled by the generic WMS specification.
The global_mosaic layer defaults to a pansharpened view of the data when a
color combination is chosen, while the global_mosaic_base does not.
Comparing this image, showing the non-pan-sharpened image, with the previous one, it
is obvious that the pansharpening affects more than just the level of detail.
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Styles represent a mechanism to modify the representation of a map.
There can be many styles defined for a given dataset, some defined
by the client, and some predefined on the server itself. Styles can
be used to change or select the band combination, and provide basic image
control such as changing the gamma value, normalize the images to
bring out more detail, remap colors, and many other uses.
Two color styles are predefined for both the pansharpened and the
non-pansharpened layers. They are the default pseudo style, using the
Landsat 7 bands 5,4 and 2 to generate the color, and the visual style,
using the visual bands 3,2 and 1.
To ilustrate these styles, the Grand Canyon area is used. The left side of the
image is using the default or pseudo style, while the right hand uses
the visual style. Since our browser can only use one style at a time,
clicking on the image will start the browser page with one of the color styles,
depending on the position of the selected point.
If you examine the URLs generated by the image, the only difference should be
the value of the styles paramter.
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In addition to the color styles, 9 separate grayscale styles are defined, one for
each Landsat 7 bands. The style names are
Blue Green Red IR1 IR2 IR3 ThL ThH Pan
These styles select a single spectral band out of the mosaic. The Blue Green and Red
styles correspond to the respective visual wavelength bands. The IR1 IR2 and IR3
styles select one of the three infrared bands. ThL and ThH correspond to the
thermal band, with either High or Low gain. The last style, Pan,
selects the wide band, panchromatic data.
The pansharpening operation can not be applied to a single band, these styles should
produce identical results for the global_mosaic or global_mosaic_base
layers.
The image shows the nine different bands or styles, for a large region
of the southwestern US.
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| Combined dataset use and SLD: |
This is an example on how to build a custom map, the result of using two layers,
using different styles and custom SLD based color pallete mapping, to produce a
complex visual effect.
All processing takes place on the server, and a single image is sent back to
the client browser.
Whie the images on this page are simple image files residing on the server,
they have been generated by the associated WMS server.
Clicking on any of these pictures will load an active WMS browser that allows
pan and zoom of the corresponding view.
The first image is the background. It is obtained from the global_mosaic
layer, and it is using the default style. Note the sld parameter. It
contains an encoded URL that will be used as a source for client side styles.
This document does not contain anything used to generate this image, it will be
used for the other images in this exercise. You can of course download and examine
this XML formated document.
Only one URL is used for all layers, and the custom styles must be defined for
each specific layer requested. Since it is being located via an URL, this type
of document could reside on a remote web server. It is being retrieved every time
an image is being requested, and as such it can have a considerable effect on
how long it takes to generate an image.
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The foreground uses an elevation derived image. The "purple haze" style defined
in this SLD maps three different regions to various colors,
using an RGBA colormap. To generate a colormap a few tie-points are necessary and the server
uses linear interpolation to generate the complete color map. This is the behavior described in the OGC SLD standard. This particular WMS server generates only 256 color entries, equaly spaced between the first and the last value of the input values provided in the SLD.
The color map used here makes most of the elevation range fully transparent. In this figure we made the browser background black to better ilustrate these areas of transparency. Elevations between 1 and 100 meters above the water level are half opaque, with the color changing from blue to green. From 1000 meters to 1100 meters elevation, the image becomes blue then back to full transparent. The last color zone is used to make the elevations between 2000 and 3000 meters brighter, starting with a pale redish tinge and continuing to a pure opaque white for values above 4000 meters.
Some quantization artifacts are evident in this view, since only 256 colormap entries are used to map elevations in the 0 to 5000 meters range.
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Combining the previous two layers to produce the desired visual effect. All processing
takes place on the server, and a single image is sent back to the browser. All of the requirements are incapsulate into the URL WMS request.
If you start the WMS viewer by clicking on the image, and examine the WMS request
used to generate the images, you will notice that the only differences between this
request and the previous single layer images reside in the layers and the
styles arguments. This is all that is needed to combine multiple layers,
they are processed in the order in which they appear in the layers parameter.
Each layer needs to have a style associated with it. If the style is not specified, the predefined "default" style for the respective layer will be used.
Of course, this process can be repeated by adding another layer on top of
the already existing stack. Response time will decrease to accomodate the increased workload. Only layers local to the server can be used for this type of processing.
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Any supported style can be used for this type of processing. In this representation, a different color mapped elevation is used together with a single band of the Landsat background.
Try changing the background by starting the browser with this image, then locate the
styles argument in the URL, and change Pan to visual or Red
The server is case sensitive, and no spaces are allowed in the URL.
The phaze style associated with the elevation layer shows how the colormap is
clamped at the edges of the specified range.
In this image, the full 256 possible color entries are used between value of 1 and
100 meters of the elvations, producing a much finer gradation.
Both RGB and RGBA colormaps are supported, but the server uses RGBA only if one of
the color entries needs more than 24 bits of data. This is accomplished in the phaze style by making the last entry #01ff0000 instead of #ff0000
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This page,
http://onearth.jpl.nasa.gov/index.html,
is maintained by
and was last modified Saturday, 08-Dec-2007 12:31:53 PST
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