SeaWiFS: Difference between revisions
Jump to navigation
Jump to search
(new) |
m (→SeaWiFS) |
||
| (4 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
== SeaWiFS == | == SeaWiFS == | ||
From the same [http://oceancolor.gsfc.nasa.gov/PRODUCTS/ OceanColor website as | From the same [http://oceancolor.gsfc.nasa.gov/PRODUCTS/ OceanColor website] as the [[MODIS]] data (gsfc.nasa.gov) you can download [http://en.wikipedia.org/wiki/Seawifs SeaWiFS] data, a particularly good source for chlorophyll-''a'' at sea and NDVI on land. | ||
* the SeaWiFS Standard Mapped Products are already geocoded in WGS84 so should be easy to load into a lat/lon location with {{cmd|r.in.gdal}} (at least this is true for PAR maps). | * the SeaWiFS Standard Mapped Products are already geocoded in WGS84 so should be easy to load into a lat/lon location with {{cmd|r.in.gdal}} (at least this is true for PAR maps). | ||
* Processing is very similar to the [[MODIS]] examples. | * Processing is very similar to the [[MODIS]] and [[AVHRR]] examples. | ||
In some data I worked with, NULL was represented by -32767. This can be cleaned up using the {{cmd|r.null}} module: | |||
MAP=S2010235.L3m_DAY_CHL_chlor_a_9km | |||
r.null $map setnull=-32767 | |||
Inspecting the HDF file with "gdalinfo" tell us that this data has a slope of 1 and intercept of 0, so does not need to be processed with {{cmd|r.mapcalc}}. | |||
You can download some preprocessed color rules for Chlorophyll-''a'' from the GRASS addons SVN (based on NASA's GSFC OceanColor website's rules) and apply them with the {{cmd|r.colors}} module. | |||
r.colors $map rules=~/grass_addons/palette_chl_etc.gcolors | |||
or use a simple equalized histogram to spread the colors to where the data is: | |||
r.colors $map color=bcyr -e | |||
=== See also === | |||
* [[MODIS]] | |||
* [[AVHRR]] | |||
[[Category: Geodata]] | |||
Latest revision as of 07:00, 6 September 2010
SeaWiFS
From the same OceanColor website as the MODIS data (gsfc.nasa.gov) you can download SeaWiFS data, a particularly good source for chlorophyll-a at sea and NDVI on land.
- the SeaWiFS Standard Mapped Products are already geocoded in WGS84 so should be easy to load into a lat/lon location with r.in.gdal (at least this is true for PAR maps).
In some data I worked with, NULL was represented by -32767. This can be cleaned up using the r.null module:
MAP=S2010235.L3m_DAY_CHL_chlor_a_9km r.null $map setnull=-32767
Inspecting the HDF file with "gdalinfo" tell us that this data has a slope of 1 and intercept of 0, so does not need to be processed with r.mapcalc.
You can download some preprocessed color rules for Chlorophyll-a from the GRASS addons SVN (based on NASA's GSFC OceanColor website's rules) and apply them with the r.colors module.
r.colors $map rules=~/grass_addons/palette_chl_etc.gcolors
or use a simple equalized histogram to spread the colors to where the data is:
r.colors $map color=bcyr -e