This function creates a new ENVIRaster from a file or uniform resource indicator (URI).

Syntax

Result = ENVIURLRaster(URI [, Keywords=value])

Return Value

This method returns a reference to an ENVIRaster.

Arguments

URI

For local datasets, specify a scalar string that is a fully-qualified file path to a raster on disk.

For remote datasets, specify a string with the direct URL of the dataset. You can connect directly to an OGC server, ArcGIS image service, or Jagwire server. The connection string is formatted the same as the URL field in the Open Remote Dataset dialog. See Using the Open Remote Dataset Dialog for examples of connection strings for different data types. If you connect to a remote dataset that requires authentication, you must set the USERNAME and PASSWORD keywords. Or, optionally set the /PROMPT_USER keyword to enter the user name and password.

Keywords

Keywords are applied only during the initial creation of the object.

DATA_IGNORE_VALUE

Set this keyword to a pixel value that will be ignored when the raster is displayed. This overrides any data ignore values set in the metadata.

DATASET_INDEX

This keyword applies to file formats with multiple datasets per file such as ECRG, HDF5, Multi-page TIFF, NetCDF-4, NITF with multiple image segments, Proba-V, and SkySat-1. Specify a zero-based index number that corresponds to a specific raster dataset that you want to open within the file. For example, DATASET_INDEX=0 will open the first raster.

You cannot set this keyword in conjunction with the TEMPLATE keyword.

• Multi-page TIFF: Specify an index number with the specific page to open. For example, DATASET_INDEX=5 will open the sixth page.
• NITF: For files with multiple image segments, specify an index number corresponding to an individual image segment. DATASET_INDEX=0 will open the first image segment.
• Proba-V with radiometry:
  • DATASET_INDEX=0: VNIR band
  • DATASET_INDEX=1: SWIR band
  • DATASET_INDEX=2: NDVI band
  • DATASET_INDEX=3: Quality band
• Proba-V without radiometry:
  • DATASET_INDEX=0: NDVI band
  • DATASET_INDEX=1: Quality band

DATASET_NAME

This keyword applies to file formats with multiple datasets per file such as ECRG, HDF4, HDF5, Multi-page TIFF, NetCDF-4, Proba-V, and SkySat-1. For NITF files with multiple image segments, use the DATASET_INDEX keyword instead.

Set this keyword to a string with the name of a raster dataset that you want to open within the file. Strings are case-sensitive.

If you do not know the dataset names, use the Dataset Browser to open the files and obtain the names.

You cannot set this keyword in conjunction with the TEMPLATE keyword.

HDF5 example

For HDF5 files, you can use the IDL H5_LIST routine to list the dataset names. This example uses an HDF5 file included in the ENVI+IDL installation. Set INSTALL_DIR to the correct installation path and xx to the correct version of IDL:

File = 'INSTALL_DIR\IDLxx\examples\data\hdf5_test.h5' 

H5_LIST, File

IDL prints:

% Loaded DLM: HDF5.

file INSTALL_DIR\IDLxx\examples\data\hdf5_test.h5

dataset/2D int array                                                          H5T_INTEGER [50, 100]

dataset          /A note H5T_STRING [2]

group              /arrays

dataset          /arrays/2D float array H5T_FLOAT [50, 100]

dataset          /arrays/2D int array H5T_INTEGER [50, 100]

...

etc.

Then enter the following command:

Raster = e.OpenRaster(File, DATASET_NAME='/arrays/2D float array')

SkySat-1 example

Set the URI argument to a metadata file. Valid strings for DATASET_NAME include Panchromatic, Multispectral, or Pan Sharpened.

File = 'C:\Data\s01_20140315T161938Z\s01_20140315T161938Z_metadata.txt'

Raster = e.OpenRaster(File, DATASET_NAME='Panchromatic')

SkySat rasters open in their native spatial reference (typically RPC). They do not reproject as they would in the ENVI user interface.

Proba-V S10 example

Valid strings include VNIR, SWIR, NDVI, and Quality.

File = 'PROBAV_S10_TOC_X19Y03_20131121_333M_V001.h5'

Raster = e.OpenRaster(file, DATASET_NAME='NDVI')

ERROR

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

FORMAT

Use this keyword to identify the format of the raster. If it is a known native format, then this keyword will be ignored. If it is a known external format, then the raster will open according to that format. All other values for this keyword are handled using the value as a custom open procedure.

The native formats are: bmp, envi, esri_grid, imagine, jp2, jpeg, kompsat2, landsat_metadata, mrsid, nitf, qb_tile, rapideye, tiff, tfrd, and wv_tile.

The known external formats are in this table:

acres

ads40 

alos

arcview

atsr

avhrr

avhrr_sharp

cadrg

cib

cosmo-skymed

dmc

dmsp_noaa 

ecw

envisat

eo1_hdf

eos_aster

eos_modis 

er_mapper 

erdas_lan

eros_l1a

eros_l1b

ers

formosat-2

irs_fast 

irs_super_structured

jers 

landsat_ceos

landsat_fast

landsat_hdf

landsat_mrlc

landsat_nlaps

master

pci

pds

pict

png

radarsat

seawifs

spot_cap_sisa 

spot_geospot 

spot_vegetation 

srtm_dem

srf

tims 

topsar

usgs_doq 

usgs_drg 

usgs_native_dem 

usgs_sdts_dem

xwd

INTERLEAVE

This keyword only applies to three-dimensional datasets and specifies the interleave of the dataset when an interleave is not specifically defined in the file (as with HDF5 datasets). Set this keyword to one of the following strings:

This keyword is optional and the default value 'bsq' is used if it is not set. You can only set this keyword if you also set DATASET_NAME.

METADATA_OVERRIDE

Set this keyword to an ENVIRasterMetadata object. The metadata information for the newly created ENVIRaster will be taken from both the specified object and the ENVIRaster on disk (specified with URI).

If the ENVIRasterMetadata object specified by this keyword and the ENVIRaster specified by URI both have the same tag, the tag information from the ENVIRasterMetadata object will take precedence. Although this process only happens in memory, the information will be persisted to a header file if the ENVIRaster::WriteMetadata method is called.

If the ENVIRasterMetadata object contains the string 'read procedures,' then the ENVIRaster is opened using a custom read routine.

The DATA_IGNORE_VALUE keyword takes precedence over the METADATA_OVERRIDE keyword.

For NPP VIIRS files, only the I, M, DNB, or NCC bands (rasters) can be overridden. Metadata override is not allowed for the Latitude, Longitude, Height, or Quality bands.

PASSWORD

Set this keyword to a string with a valid password for opening a remote dataset that requires authentication.

PROMPT_USER

Set this keyword in an interactive session (not for use with batch mode) if you want ENVI to prompt you for certain input parameters instead of performing default actions.

If you set the PROMPT_USER keyword and open an NPP VIIRS dataset, the NPP VIIRS Parameters dialog will appear for you to select calibration options. If you do not set this keyword and you open an NPP VIIRS dataset, the dataset will be calibrated to radiance, by default.

SPATIALREF_OVERRIDE

Set this keyword to an ENVIPseudoRasterSpatialRef, ENVIRPCRasterSpatialRef, or ENVIStandardRasterSpatialRef object. The spatial reference information for the newly created ENVIRaster will be taken from the specified object and not from the associated raster data file. Although this process only happens in memory, the information will be persisted to a header file if the ENVIRaster::WriteMetadata method is called.

If the ENVIRaster contains a combination of standard and auxiliary (RPCs or pseudo) map information, and you set SPATIALREF_OVERRIDE to an ENVIStandardRasterSpatialRef object, the original auxiliary map information will be lost.

TEMPLATE

Set this keyword to a string with the name of a custom XML template used to open NetCDF-4, HDF4, HDF-EOS, or HDF5 datasets. Creating and restoring templates can be helpful when you want to build the same raster and metadata structure from several source files. Setting this keyword assumes that you previously created a template manually or by using the Dataset Browser. See Work with Templates for more information.

You cannot set this keyword when setting DATASET_INDEX or DATASET_NAME.

TERRAIN_SOURCE (Init)

Specify a string with the terrain source to use:

• Best: Used by default if a terrain source is not specified

• DTED0

• DTED1

• DTED2

• Reference Point

• SRTM0

• SRTM1

• Terrain Base

This keyword is only available with the ENVI Department of Defense (DoD) plug-in.

TIME_OVERRIDE

Set this keyword to an ENVITime object. The time information for the newly created ENVIRaster will be taken from the specified object and not from the associated raster data file. Although this process only happens in memory, the information will be persisted to a header file if the ENVIRaster::WriteMetadata method is called.

USERNAME

Set this keyword to a string with a valid user name for opening a remote dataset that requires authentication.

UVALUE

Use this keyword only the FORMAT keyword is not a known native or external file type. The value set with this keyword will be passed into the custom open procedure's UVALUE keyword. If the custom open procedure does not accept the UVALUE keyword, then it will be ignored.

Dehydrated Form

"data_ignore_value" : -9999

"dataset_index" : 1

"dataset_name" : "cirrus"

"format" : "alos"

  "interleave" : "bip"

"metadata_override" : {

   "factory": "RasterMetadata",

   "WAVELENGTH": [485.00000000000000, 
      560.00000000000000, 660.00000000000000, 
      830.00000000000000],

   "WAVELENGTH UNITS": "Nanometers",

   "SENSOR TYPE": "QuickBird",

   "BAND NAMES": ["Band 1", "Band 2", "Band 3", "Band 4"]

}

"spatialref_override" : {

   "factory": "StandardRasterSpatialRef",

   "rotation": 0.00000000,

   "tie_point_pixel": [0.00000000, 0.00000000],

   "coord_sys_code": 32611,

   "pixel_size": [30.000000, 30.000000],

   "tie_point_map": [493785.00, 4899315.0]

}

"template" : "/mydata/my_template.xml"

"time_override" : {

   "acquisition": "2015-10-30T16:05:32.3258314Z",

   "factory": "Time"

}

"url" : "/usr/local/INSTALL_DIR/envi/data/qb_boulder_msi"

"uvalue" : 3.14159

Version History

API Version

4.3

See Also

ENVI function, ENVI::GetView, ENVIView::CreateLayer, ENVIRaster