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        SDMI ortho-mosaic source scene overview - version: 2010.10
           www.alaskamapped.org   |    orthoproj@gina.alaska.edu
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In this file package is a SPOT5 source scene that will be integrated into the
Statewide Digital Mapping Initiative (SDMI) statewide ortho-mosaic. See
http://www.alaskamapped.org/ortho

The data was produced under State of Alaska contract # DNR 10-10-062, with
Aero-Metric as prime contractor and Spot Image and Fugro Earthdata as
subcontractors.

For the initial release of the data, the FGDC metadata has not been completed.
Full FGDC metadata records will be added to the file package in late 2010.

The first thing to note is: THIS IS NOT A MAP PRODUCT.  Although geo-referenced
products are included in the file package, they are just browse images for
previewing the data. The scene has not been ortho-rectified or had any control
applied.   The scene has been rubber-sheeted on to the earth to provide a more
useful browse product; significant errors in geo-location compared to an actual
ortho-rectified, controlled map product are present in the browse imagery
herein.

The source scenes come in two pairs
  1. B: panchromatic (single band 2.5 meter resolution)
  2. J: multi-spectral (four 10 meter bands - red, green, near IR, shortwave IR)

The scene01/imagery.tif is the Level 1A product as comes from Spot Image.

Additional information about the sensor and imagery can be found here:
http://www.spot.com/web/SICORP/445-sicorp-the-spot-satellites.php

License:
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All U.S. Fed/Civ government agencies, U.S. State/Local government agencies,
U.s. higher-education institutions, and Native American Tribes are allowed to
use this dataset - See the SDMI_EULA.pdf for full details.

Websites and points of contact:
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1. http://www.alaskamapped.org/ortho # ortho project overview website
2. http://browse.alaskamapped.org/   # where to download these source scenes
3. orthoproj@gina.alaska.edu         # point of contact for questions

The gina-extras/ and sdmi/ directories
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During the GINA-SDMI ingestion process we generate various products that might
be of use to the end user.   These can be found in the gina-extras/ and sdmi/
directories.

The sdmi/_aa.tif and _aa_rgb.tif files are the scene01/imagery.tif file
rubber-sheeted onto the globe in Alaskan Albers projection as a pyramided
GeoTIFF.   THIS IS NOT A MAP PRODUCT- the rubber sheeting into Alaska Albers is
just to make it easier to preview the data in its approximate location on the
earth but does not correctly geo-locate the pixels.

  1. _aa.tif all the bands (4 for multispectral scene and just 1 for panchromatic).
  2. _aa_rgb.tif for multi-specteral scenes are the red, green and near IR bands.
  3. _aa_rgb_6k.tif is the RGB scaled to 6x000 x 6,000 GeoTIFF.
  4. _aa_rgb_6K.png is the RGB scaled to 6,000 x 6,000 PNG image with transparency.

gina-extras/ and tagger.yml are created during the GINA ingestion process.
This is the minimum metadata required to be ingested and can be useful for
quickly looking up things like acquisition dates, short description,  and how
many bands are available.


Not a map product
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This source scene is a SPOT 5 Level 1A product that has been georeferenced. It
has had no geometric terrain corrections performed (ortho-rectification) and is
not projected.  The ‘rubber sheeting’ of the source image into Alaska Albers
was done by Dayne at GINA to make it easier to interact with the data but does
place the pixels on the earth’s surface with mapping quality accuracy.

Random notes
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Saturated Pixels
1. The SPOT 5 HRG sensors have an 8-bit dynamic range and can become saturated
(max value of 255) for a variety of reasons:
1. Reflections from snow, ice, top of clouds.
2. Transitions from one major feature type to another: water to land.
3. Gain settings on satellite not optimized for terrain.
Areas of saturation are going to be blown out and lack detail.  Glaciers and
sea ice may be all white (value 255).