PNT2RAS

Description

PNT2RAS converts, or rasterizes, points in a vector layer to a raster layer. Only pixels where a point falls will be assigned a value and no interpolation will be applied.

Parameters

pnt2ras(fili, dbvs, filo, dboc, fldnme, statatt, pixres, ftype, foptions)

Name	Type	Caption	Length	Value range
FILI *	str	Input vector file name	1 -
DBVS *	List[int]	Input point layer	1 - 1
FILO *	str	Output file name	1 -
DBOC	List[int]	Output raster channel	0 - 1
FLDNME	str	Attribute field name	0 -	Default: SHAPEID
STATATT	str	Statistical operation to determine pixel value	0 -	COUNT\|FIRST\|LAST\|MAX\|MAXMAG\|MEAN\|MIN\|MODE\|RANGE\|STD\|SUM Default: MEAN
PIXRES	List[float]	Pixel resolution	0 - 2	0.000000000001 -
FTYPE	str	Output file type	0 - 4	Default: PIX
FOPTIONS	str	Output file options	0 - 64

* Required parameter

Parameter descriptions

FILI

Specifies the name of the file containing the point vector layer to rasterize.

DBVS

Specifies the vector segment containing the points to be converted to rasters.

FILO

Specifies the name of the file to receive the output raster.

If FILO specifies an existing file, the DBOC parameter must specify an existing channel, which will be updated. If FILO does not already exist, a new file will be created. The new file will base its georeferencing on the input point data.

DBOC

Specifies the output raster channel to receive the output results.

If the specified output file already exists, this parameter must specify an existing channel. DBOC defaults to 1 only when a new file is created.

When creating a new output channel, its bit depth is automatically determined, depending on the values to be written to the raster.

FLDNME

Specifies the name of the attribute field whose numerical values are to be used to assign values to the output raster pixels. If this parameter is specified as (z-coord), the z-coordinate of the first vertex of each vector shape is used. If the specified attribute does not exist and it is not (z-coord), the ShapeID of the vector shapes are used.

STATATT

Specifies a statistical operation to determine the output pixel value when more than one input point fall onto the same pixel. All of the points that are on the same output pixel will be candidates for determining the output pixel value. In particular, their attribute value (as specified by FLDNME) will be applied to STATATT. The possible STATATT options are:

COUNT: Value will be the number of candidate points.
FIRST: Value will be that of the candidate shape with the lowest ShapeID.
LAST: Value will be that of the candidate shape with the highest ShapeID.
MAX: Value will be the maximum of all the candidate point values.
MAXMAG: Value will be the candidate point value with the maximum absolute value.
MEAN: Value will be the mean (average) of all the candidate point values.
MIN: Value will be the minimum of all the candidate point values.
MODE: Value will be the most common of all the candidate point values. If multiple values occur most frequently, the output value will be that of the lowest ShapeID.
RANGE: Value will be the difference between the greatest and least of all the candidate point values. Only pixels with at least one candidate point will be assigned a value.
STD: Value will be the standard deviation of all the candidate point values. Only pixels that have more than one candidate point will be assigned a value.
SUM: Value will be the additive sum of all the candidate point values.

PIXRES

This parameter applies only when a new output file is being created. It allows you to specify a pixel resolution (in units of the input vector projection) for the output file. By default, the pixel size is set to be the same as the input file. The pixel size is used to determine the number of pixels and lines in the output file. Thus, decreasing the pixel size results in a larger output file and increased computation time.

Acceptable values are: x > 0.0, y > 0.0

FTYPE

Optionally specifies the output file format type, represented by a three- or four-letter code.

For a complete list of GDB-recognized file types and their codes, see GDB file formats in the Technical Reference section of the CATALYST Professional online Help.

FOPTIONS

Different options are available for different file types (see the FTYPE parameter). The options are described in GDB file formats in the Technical Reference section of the CATALYST Professional online Help.

For PIX format, FOPTIONS defaults to BAND.

Details

PNT2RAS converts points in a vector layer to a raster layer. Pixels will be assigned a value based on the point, or points, that they cover. Unless the point data is particularly dense and the output pixels large, you typically end up with a sparse raster with many pixels not having a point value burned into them. The output pixel value depends on the spatial relationship between that pixel and the input points. If a pixel covers no points, then it will not be changed when writing to an existing channel or set to NoData when writing to a new output channel. Except when using STATATT=COUNT, STD or RANGE, when a pixel covers a single point, the value of that pixel will be assigned directly from the corresponding value in the FLDNME field. Finally, if a pixel covers multiple points, the value assigned to that pixel will be determined by applying the specified STATATT operation to the FLDNME values. Unless writing to an existing channel, the output channel type, or bit depth, is automatically determined.

Example

Points from irvine.pix segment 32 are converted to a raster layer. The output pixel values will be the mean of the Area attribute of the input points over each pixel. A new file to hold the raster will be created called irvine32ras.pix.

from pci.pnt2ras import pnt2ras

fili     = "irvine.pix"      # input file with point layer
dbvs     = [32]              # point layer
filo     = "irvine32ras.pix" # output file to be created
dboc     = []                # output channel will be created
fldnme   = "Area"            # use Area attribute as pixel values
statatt  = "MEAN"            # Take the mean of all points in each pixel
pixres   = [60,60]           # make 60 meter square pixels
ftype    = "PIX"             # output format type
foptions = ""                # output format options

pnt2ras( fili, dbvs, filo, dboc, fldnme, statatt, pixres, ftype, foptions )

Environments	PYTHON :: EASI
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