ASCIIToROI Task

This task creates a single ROI from the geometry of a columned ASCII file.

Example

This example opens a column-delimited ASCII file containing meteorological data for 15 weather stations. The first column contains geographic longitudes, and the second column contains latitudes. The ASCII data are converted to ROI points and displayed on top of a shaded-relief image.

; Start the application

e = envi()

; Open an ASCII file

ASCIIFile = FILEPATH('ascii.txt', $

  SUBDIRECTORY = ['examples', 'data'])

; Open a shaded relief image

ImageFile = Filepath('natural_earth_shaded_relief.jp2', $

  Subdir=['data'], Root_Dir=e.Root_Dir)

Image = e.OpenRaster(ImageFile)

; Get the task from the catalog of ENVITasks

Task = ENVITask('ASCIIToROI')

; Define inputs

Task.INPUT_URI = ASCIIFile

Task.LINES_TO_SKIP = 5

Task.ROI_NAME = 'Weather stations'

; Specify column 1 for X coordinate and

; column 2 for Y coordinate

Task.DATA_COLUMNS = [1,2]

; Run the task

Task.Execute

; Display the result

View = e.GetView()

Layer = View.CreateLayer(Image)

roiLayer = Layer.AddROI(Task.OUTPUT_ROI)

Extent = Task.OUTPUT_ROI.GetExtent(Image)

View.SetExtent, Extent, DATA=Layer

Syntax

Result = ENVITask('ASCIIToROI')

Input properties (Set, Get): COORD_SYS, DATA_COLUMNS, GEOMETRY_TYPE, INPUT_URI, LINES_TO_SKIP, OUTPUT_ROI_URI, ROI_COLOR, ROI_NAME

Output properties (Get only): OUTPUT_ROI

Properties marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Properties marked as "Get" are those whose values you can retrieve but not set.

Methods

This task inherits the following methods from ENVITask:

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

COORD_SYS (optional)

Specify the input coordinate system of the incoming geometry.

DATA_COLUMNS (required)

Specify an integer array with the column numbers corresponding to X and Y geometry data. The X column contains longitudes or eastings. The Y column contains latitudes or northings. For example, if the third column of the ASCII file contains longitudes and the fourth column contains latitudes, set DATA_COLUMNS to [3, 4].

GEOMETRY_TYPE (optional)

Specify a string indicating the geometry type. The choices are:

Polygon
Polyline
Point (default)

INPUT_URI (required)

Specify the fully qualified URI to an input ASCII file that contains the geometry records.

LINES_TO_SKIP (optional)

Specify the number of lines to skip at the beginning of the ASCII file.

OUTPUT_ROI

This is a reference to the output ROI.

OUTPUT_ROI_URI (optional)

Specify a string with the fully qualified path and filename for OUTPUT_ROI.

ROI_COLOR (optional)

Specify a three-element byte array with the color of the output ROI; for example: [0, 128, 0].

ROI_NAME (optional)

Specify a string with the name of the output ROI.

Version History

ENVI 5.5.3

Introduced

API Version

4.2