ENVIGeoJSONToROITask

This task converts GeoJSON features to a region of interest (ROI).

GeoJSON is a geospatial format based on JSON code that is used for encoding geographic data structures. For more information, see the GeoJSON Format Specification. Also see the GeoJSONLint web page for example code and for tools that validate GeoJSON code.

Example

; Start the application

e = ENVI()

; Open an input file

File = Filepath('qb_boulder_msi', Subdir=['data'], $

  Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Define a GeoJSON object

jsonString = '{"type": "GeometryCollection",' + $

              '"crs": {' + $

                '"type": "name",' + $

                '"properties": {' + $

                '"name": "urn:ogc:def:crs:EPSG::4326"' + $

                '}' + $

              '},' + $

             '"geometries": [' + $

               '{"type": "MultiPolygon",' + $

                '"coordinates": '+ $

                  '[' + $

                    ; Outer Polygons

                    '[' + $

                       ; water 1

                       '[ [-105.20418905,40.00161644],' + $

                       '[-105.20579077,39.99951061],' + $

                       '[-105.20243658,39.99929828],' + $

                       '[-105.20418905,40.00161644] ],' + $

                       ; water 2

                       '[ [-105.22100219,39.99188934],' + $

                       '[-105.22120192,39.99157745],' + $

                       '[-105.22077586,39.99159722],' + $

                       '[-105.22100219,39.99188934] ]' + $

                       '],' + $

                       ; holes

                       '[]' + $

                     '],' + $

             ' "properties":{'+$

                 '"name": "water",' + $

                 '"color": [0,0,255]' + $

                 '}' + $

               '},' + $

               '{"type": "MultiPolygon",' + $

             '"coordinates": '+ $

               '[' + $

                 ; Outer Polygons

                 '[' + $

                    ; grass

                    '[ [-105.21645204,39.98990144],' + $

                    '[-105.21706805,39.98894798],' + $

                    '[-105.21554790,39.98946003],' + $

                    '[-105.21645204,39.98990144] ]' + $

                 '],' + $

                 ; holes

                 '[]' + $

               '],' + $

              ' "properties":{'+$

                  '"name": "grass",' + $

                  '"color": [0,255,0]' + $

                  '}' + $

               '},' + $

               '{"type": "MultiPolygon",' + $

              '"coordinates": '+ $

                '[' + $

                  ; Outer Polygons

                  '[' + $

                   ; roof

                   '[ [-105.20932273,40.00311630],' + $

                   '[-105.20942141,40.00299338],' + $

                   '[-105.20909107,40.00295165],' + $

                   '[-105.20900897,40.00309994],' + $

                   '[-105.20932273,40.00311630] ]' + $

                   '],' + $

                   ; holes

                   '[]' + $

                '],' + $

               ' "properties":{'+$

                   '"name": "roof",' + $

                   '"color": [255,255,0]' + $

                   '}' + $

                 '}' + $

               ']' + $

'}'

; Get the task from the catalog of ENVITasks

task = ENVITask('GeoJSONToROI')

; Define task inputs

task.Input_GeoJSON = ENVIGeoJSON(JSON_Parse(jsonString))

; Run the task

task.Execute

; Display the result

view = e.GetView()

layer = view.CreateLayer(Raster)

rois = task.OUTPUT_ROI

roiLayers = OBJARR(N_ELEMENTS(rois))

FOR i=0, N_ELEMENTS(rois)-1 DO roiLayers[i] = layer.AddROI(rois[i])

Syntax

Result = ENVITask('GeoJSONToROI')

Input properties (Set, Get): INPUT_GEOJSON, OUTPUT_ROI_URI

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

INPUT_GEOJSON (required)

Specify an input GeoJSON object.

ENVI currently supports GeometryCollection type objects. These objects can only contain one or more MultiPolygon type geometries.
The crs tag is not required. If the code contains this tag, ENVI converts it to a string. Otherwise, it uses a default value of wgs84.
You can add name and color properties to each MultiPolygon object. See the example code in this topic.

To ensure properly validated GeoJSON code, refer to the GeoJSONLint web page.

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.

Version History

ENVI 5.3

Introduced

API Version

3.3