CoastWatch Data Formats and GIS: Binary Raster


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Binary Raster The ESRI binary raster format is a binary format file designed for import into the ArcView or ARC/INFO GIS packages. By using the CoastWatch Software and Utilities, many of the CoastWatch products can be converted into this format. There are two files, the IEEE floating-point file (.flt) and a supporting ASCII header file (.hdr). The header file must have the same name as the data file, but with a .hdr file extension. The header data includes the following keywords and values:

ncols number of columns in the data set.

nrows number of rows in the data set.

xllcenter or xllcorner x-coordinate of the center or lower-left corner of the lower-left cell.

yllcenter or yllcorner y-coordinate of the center or lower-left corner of the lower-left cell.

cellsize cell size for the data set.

nodata_value value in the file assigned to cells whose value in unknown. This keyword and value is optional.

byteorder the byte order of the binary cell values. You can choose between two keywords, msbfirst or lsbfirst. Msbfirst is used for cell values written with the most significant bit first. Lsbfirst is used for cell values written with the least significant bit first.

For example,

                              ncols 480
                              nrows 450
                              xllcorner 378923
                              yllcorner 4072345
                              cellsize 30
                              nodata_value -32768
                              byteorder msbfirst

The data file will be a matrix of 32 bit signed IEEE floating-point values. The file will have a line of binary numbers for each row in the data set. The first line of data is the top row of the data set, moving from left to right.

ArcView:

Using the ArcView Spatial Analyst extension, import the .FLT binary data file as a GRID. Make sure that the the .HDR header file is in the same directory - ArcView needs this file for geographic information.
After adding the new GRID theme to the view, set the projection of the view to Mercator before overlaying any other GIS themes.
You should be able to load multiple CoastWatch data files for different areas of the U.S. Coast as GRID themes in the same view to create a mosaic effect.

ARC/INFO:

Start an Arc session and use the FLOATGRID command to import the binary GRID and ASCII header file. For example:
```
      FLOATGRID w9813721.sc4.flt w9813721_sc4
    
```

Use the PROJECT command to project the new GRID file to a custom projection. The input projection should be specified as follows:

      projection mercator
      units meters
      spheroid sphere
      parameters
      00 00 00
      00 00 00
      0.0
      0.0

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The NOAA CoastWatch Program is operated within NOAA's National Environmental Satellite Data Information Service (NESDIS). NOAA is a part of the Department of Commerce (DOC).
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