Raster to ASCII

Data Description

• The input raster dataset can be any valid raster dataset.

• The structure of the ASCII file consists of a header with a series of keywords, followed by pixel values arranged in row-major order.

  The format of the file generally is:

  ncols xxx
  nrows     xxx
  xllcorner xxx
  yllcorner xxx
  cellsize xxx
  NODATA_value xxx
  row 1
  row 2
  .
  .
  row n
  

  The definitions of the keywords are as follows:

  • ncols and nrows: The number of columns and rows in the raster as defined by the ASCII file.
  • xllcorner and yllcorner: The coordinates of the lower-left corner of the raster cell.
  • cellsize: The size of each raster cell.
  • NODATA_value: The value used to represent NoData cells.
  • In the pixel value data stream, the first row of data is at the top of the raster, the second row is directly below the first row, and so on.

• Here is an example of an ASCII raster file:

  ncols 480
  nrows     360
  xllcorner 398722
  yllcorner 4152341
  cellsize 25
  NODATA_value -9999
  9 18.150000 16.850000 16.790001 16.700001 16.540001 15.800000 17.870001 22.780001 17.049999 11.960000 9.460000 9.510000 9.600000 10.520000 11.810000 12.310000 12.500000 12.970000 13.100000 13.390000 13.910000 14.700000 15.190000 ...
  

• NODATA_VALUE: The value used in the ASCII file to represent NoData cells in the input raster. This value is typically reserved for pixels where the "true" value is unknown.

• In the file, each line of raster data ends with a carriage return.

• Both integer and floating-point rasters can be converted to ASCII raster files.
• This tool writes the lower-left corner of the lower-left pixel as the origin.

Steps

1. Locate the Raster to ASCII tool under Raster Tools in the toolbox, and double-click to open the tool's window.

Raster to ASCII

Parameter Description:

• Input Raster: The input raster dataset, which can be either integer or floating-point data.
• Output ASCII Raster File: The output ASCII raster file.