NUMWRIT

Description

Writes image data gray-level values from database image channel(s) to a text file or LASF file.

Parameters

Name	Type	Length	Value range
Input: Layers to be Processed: Input raster channel(s) *	Raster port	1 - 1024
Mask: Area mask	Bitmap port	0 - 4	Xoffset, Yoffset, Xsize, Ysize
Resample Mode: Resample mode	Raster port	5 - 1	Nearest, Bilinear, Cubic Default: Nearest
Output Form	String	4 - 1	COORD | DATA | GEOCOORD | LASFZ | LASFInten Default: COORD
Sampling Interval	Integer	0 - 2	1 - Default: 1,1
Text Output File *	String	1 -

* Required parameter

Parameter descriptions

Input: Layers to be Processed: Input raster channel(s)

Specifies the image channel(s) for which the gray values are to be written to the output text file or LASF file. Complex channels cannot be processed.

Mask: Area mask

Specifies the bitmap that defines the area to be processed within the input raster.

If no value is specified, the entire channel is processed.

Resample Mode: Resample mode

Specifies the type of resampling method that is used. Resampling extracts and interpolates the gray levels from the original pixel locations to corrected locations.

Output Form

Specifies the format in which image data will be stored in the output text file or LASF file.

For the coordinate (COORD) format, the text file contains two values for each pixel: database x-position (pixel) and database y-position (line), and is followed by gray-level value(s) pertaining to each input channel (in pixel-interleave mode). You may specify the number of pixels to be output on each line of text using the "COORDn" form. For example if n=2 (that is, "COORD2"), 2 pixels (6 values) will be output on each line for one input channel. If the number of input channels is four, and n=2 ("COORD2"), four pixels (x,y coordinate and two gray-level values) will be output on each line, for a total 12 columns. If no n value is specified, by default 1 pixel will be output per line.

For the georeferenced coordinate (GEOCOORD) format, the content of the text file is similar to that of the COORD format except that the (x,y) position is expressed in georeferenced units. You may specify the number of pixels to be output on each line of text using the "GEOCOORDn" form. For example, if n=2 (that is, "GEOCOORD2"), 2 pixels (6 values) will be output on each line, if DBIC is equal to one. If no n value is specified, by default 1 pixel will be output per line for 8-bit, 16-bit or 32-bit channels.

For the data ("DATA") format, the text file will contain a gray-level value for each pixel (one gray-level value for each input channel, DBIC). You may specify the number of pixels to be output on each line of text using the "DATAn" form. For example, if n=2 (that is, "DATA2"), 2 pixels (2 values) will be output on each line. If no n value is specified, by default 1 pixel will be output per line.

For the LASF format, the output is not a text file but a LAS Format Lidar point file. For both LASF options, the x and y coordinates of the point come from the x and y of the pixel. The pixel value is written to the z coordinate of the point (for a DEM for example) for the LASFZ option. For the LASFInten option the pixel value is written to the point intensity attribute field. All points are written to the first returns. X and Y offset and scaling are set from the minimum x and y values and the range of values. The Z offset and scaling are set from the raster elevation offset and scaling metadata if they are present. Otherwise the offset is 0 and the scaling is 0.001 for millimeter scaling.

The LAS format has a limit to the number of points that can be in a file. For this reason and in order to keep the number of points in a file manageable, when one billion points have been written to the LAS file, the file is closed and further points are written to an overflow file or files. The first file has the same name as specified in the TFILE parameter with a suffix "_1" and subsequent files have a corresponding suffix. If only one file was needed to contain the points then the output file name is the value of the TFILE parameter.

All options listed above may be followed, without any intervening spaces, by a comma and a keyword SUPPRESS. If this keyword is present, pixels are omitted from output if any of their channels has either a no-data or a failed value. These values are extracted from the metadata tags NO_DATA_VALUE and FAILED_VALUE of individual channels. If a channel has no such tag, the tag from the file is used, if present.

Sampling Interval

Specifies the sampling interval in pixel (X) and line (Y) direction to write out the converted data. The default is 1,1.

Text Output File

Specifies the path and file name of the text file or LASF file to which the image channel data will be written.

The output file must not already exist before running NUMWRIT.

Details

NUMWRIT transfers image data from a specified image channel (DBIC) of the input file (FILE) to the specified output text file or LASF file (TFILE). The image gray-level values are transferred in a format that can be read by other third-party programs.

The MASK parameter specifies the area within the input channel(s) from which gray-level values will be written to the text file or LASF file (TFILE).

If the MASK parameter is not specified, the entire image is processed and written to the output text file or LASF file.

If more than one input channel is specified, NUMWRIT writes the data into the text file in pixel-interleave format (BIP).

By default all selected pixels are written out. However, if the comma-separated SUPPRESS option is added to the NUMFORM parameter, then only pixels with all valid values are written. The per-channel invalid values are extracted from the no-data value or failed value metadata tags of each channel. If a channel has no tags, the values from the file-level tags are used; if they are not set, then all pixels of a given channel are treated as valid.