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Home > 5. Gridded Data

5. Gridding Marine Data and Handling Grid Products

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General:  The MDL resources do not offer a rigorous study of gridding, so serious students who want to know more about the subject should consult the literature and the various OceanTeacher articles cited in the exercises below.  The intent here is to provide the big picture of what grids are, how they are made and managed, and how they are used with other marine data.  These basic "mechanics" are often much more valuable to new data managers than the complexities of various gridding algorithms and their applications.

A serious data import problem has been discovered in Saga, concerning NetCDF grids.  For now, use IDV or ncBrowse to visualize NetCDF grids.  I'll let you know when Saga is fixed, and how to get the new version.

Related Exercises in Other Groups:

• 2.19 Visualizing Grid Analyses in IDV: THREDDS

• 2.28 Reprojecting Grid Data in Saga:  WGS84 to UTM

• 8.8 Viewing and Managing Well-Formed NetCDF Grids in Saga and IDV

• 9.12 Converting Rasters and Vectors to Google Earth Images, using IDV

• 9.40 Extracting Time-Series Plots for Points in 3-D Grids with IDV: Models or Climatologies

Exercises in this Group:

• 5.1 Converting a Data Table to a Point Shape in Saga

  • Load TSV-type table into Saga

  • Export point shape

• 5.2 Gridding Point Shapes in Saga

  • Basic gridding exercise

  • Uses INVERSE DISTANCE WEIGHTED method

• 5.3 Resampling Gridded Data to the Project Map Extent with a "Dummy" Grid in Saga

  • Frequently used method to reduce/resize any grid to a different grid system

  • 5.3.1 Accuracy Check for Grid Resampling

• 5.4 Masking Methods for Depth- or Height-Limited Grids in Saga

  • General method to leave blank all grid cells above or below a certain value

• 5.5 Creating "Standard" Grid Products with Saga

  • Making PNG + PGW (or other common graphic formats)

  • Making PNG + KML (or KMZ format if compressed)

  • Making GeoTIFF data raster format

• 5.6 Creating Color Palettes for Standard Product Rasters in Saga

  • General methods to create or work with color palettes for grids

• 5.7 Handling Classified Grids with Saga: GLCF AVHRR Classifications

  • Subsetting classified grids to preserve original information

  • Working with color palettes for classified grids

• 5.8 Creating Legends for Grids in Google Earth

  • Create a legend during the image export process

  • Write KML content to add the legend to KML displays

  • Make white margins around Saga maps invisible by tagging them as transparent

• 5.9 Correcting Faulty FillValue (i.e. Blank) Declarations in NetCDF Grids

  • Identify cases of faulty blank declarations

  • Obtain and install a necessary NetCDF editor

  • Write and run a bat file that runs the NetCDF editor to correct the declaratio

• 5.10 Basic Grid Operations, Calculations and Subsetting in IDV

  • Access methods to create various statistical grids in IDV (e.g. minima, maxima, average)

  • Calculate difference grids that compare any two grids

• 5.11 Converting Between 0-to-360º and -180-to-180º Grids in IDV

  • Move easily between Atlantic-centered and Pacific-centered views, so long as the grids are exactly 360º wide

• 5.12 Deprecated

• 5.13 Using Grid Statistics and Calculations for Ecological Assessments in Saga

  • Assemble a group of grids for a specific area, representing different seasons or conditions

  • Calculate new grids representing, for example, the AVERAGE, MINIMUM or MAXIMUM values (among others)

  • Use these new grids to calculate other products, such a value ranges, etc.

• 5.14 Managing NetCDF, HDF4/5 and GRIB Rasters with Principal Display Programs

  • Use a suite of grids to test loading, viewing and extracting subsets

  • Tests Saga, ncBrowse, Integrated Data Viewer

• 5.16 Converting Between 0-to-360º and -180-to-180º Grids in Saga

• 5.17 Creating a Histogram in Excel for IDV Grids

• 5.18 Convert GRIB Format to NetCDF with ToolsUI from UNIDATA

• 5.19 Convert NetCDF or GRIB grids to Excel with IDV - Under construction

• 5.20 Navigating an Image (to Geolocation) in IDV - Under construction