SMBOYLE

Description

SMBOYLE performs vector smoothing using the Boyle algorithm. The user defines the number of vertices to look ahead before applying the specified tolerance value to determine the new,"smoothed" vertex.

Parameters

smboyle(fili, filo, dbvs, tolvalue, lookahed, dbsn, dbsd)

Name	Type	Caption	Length	Value range
FILI*	str	Input file name	1 -
FILO	str	Output file name	0 -
DBVS*	List[int]	Input vector segment	1 - 1
TOLVALUE	List[float]	Tolerance value	0 - 1	0 - Default: 0.5
LOOKAHED	List[int]	Vertex look ahead value	0 - 1	1 - Default: 1
DBSN	str	Output segment name	0 -	Default: Vectors
DBSD	str	Output segment description	0 -

* Required parameter

Parameter descriptions

FILI

Specifies the name of the PCIDSK image file containing the input arc layer to be smoothed.

FILO

Specifies the name of the PCIDSK image file to receive the smoothed output vector layer.

If FILO is not specified, FILI is used for the smoothed vector. If FILO is specified but does not exist, a new file is created.

DBVS

Specifies the vector segment containing the input arc layer to be smoothed.

TOLVALUE

Specifies the tolerance value, which is the proportion of distance to place the new vertex between the start vertex and the look ahead vertex.

This value must be greater than zero and smaller than one. The larger the tolerance value, the more pronounced the smoothing effect.

LOOKAHED

Specifies the vertex look ahead value, the number of vertices to "look ahead" each time, before it calculates a new vertex for the resultant smoothed vector.

The look ahead value must be greater than or equal to 1.

DBSN

Specifies a name (up to 8 characters) for the new vector segment.

DBSD

Describes (in up to 64 characters) the contents or origins of the new vector data.

Details

The SMBOYLE algorithm produces better results from digitized vectors. For vectors produced by raster-to-vector conversion programs (stepped linework), the "look ahead" value has a large influence; SMMCMASTER is more suited to these vectors. SMBOYLE is not suitable for vectors containing few vertices (the result of raster-to-vector conversion programs can often create these), including small, closed shapes.

SMBOYLE does not alter the start and end vertices of a vector.

Example

Smooth vector layer 25 from "irvine.pix" with TOLVALUE of 0.5 and no sliding average option. The smoothed vector will be stored in a new file named "oirvine.pix".

from pci.smboyle import *

fili      =  "irvine.pix"
filo      =  "oirvine.pix"
dbvs      =  [25]
tolvalue  = []              # defaults to 0.5
lookahed  = []              # defaults to 1
dbsn      = ""              # defaults to Vectors
dbsd      = ""              # will be taken from dbvs

smboyle( fili, filo, dbvs, tolvalue, lookahed, dbsn, dbsd )

Environments	PYTHON :: EASI :: MODELER
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