GBDX

ENVI® Spectral Indices

This task creates a spectral index raster with one or more bands, where each band represents a different spectral index. Spectral indices are combinations of surface reflectance at two or more wavelengths that indicate relative abundance of features of interest. Vegetation indices are the most popular type, but other indices are available for burned areas, man-made (built-up) features, water, and geologic features.

GBDX Registered Name: ENVI_SpectralIndices
Provider: Harris Geospatial Solutions

Imagery Examples

Before: WorldView 2 Image after AOP correction

Before: WorldView 2 Image after AOP correction

After: WorldView 2 image after applying an NDVI.

After: WorldView 2 image after applying an NDVI.

Quickstart

This is a workflow example for basic processing.

# Quickstart Example running the task name.

# Initialize the Environment.
from os.path import join, split
from gbdxtools import Interface
gbdx = Interface()

tasks = []
output_location = 'ENVI/SpectralIndices'

# Change Detection task setup
cat_id = '103001001EC17D00'

# Image Auto ordering task parameters
order = gbdx.Task("Auto_Ordering")
order.inputs.cat_id = cat_id
order.impersonation_allowed = True
order.persist = True
order.timeout = 36000
tasks += [order]

# Image AOP task parameters
aop = gbdx.Task("AOP_Strip_Processor")
aop.inputs.data = order.outputs.s3_location.value
aop.inputs.bands = 'MS'
aop.inputs.enable_dra = False
aop.outputs.data.persist = True
aop.outputs.data.persist_location = join(output_location, '/aop')
aop.timeout = 36000
tasks += [aop]

# Create an NDVI Product
envi_spec_ind = gbdx.Task("ENVI_SpectralIndices")
envi_spec_ind.inputs.input_raster = aop.outputs.data.value
envi_spec_ind.inputs.index = '["Normalized Difference Vegetation Index", "WorldView Built-Up Index"]'
tasks += [envi_spec_ind]

workflow = gbdx.Workflow(tasks)
workflow.savedata(
    envi_spec_ind.outputs.output_raster_uri, location=output_location
)

workflow.execute()

Inputs

The following table lists all ENVI_SpectralIndices inputs.
Mandatory (optional) settings are listed as Required = True (Required = False).

Name Required Default Valid Values Description
file_types False N/A string GBDX Option. Comma seperated list of permitted file type extensions. Use this to filter input files -- Value Type: STRING[*]
input_raster True N/A See ENVIRASTER input type Specify a raster from which to generate a spectral index raster. -- Value Type: ENVIRASTER
input_raster_format False N/A See ENVIRASTER input type Provide the format of the image, for example: landsat-8. -- Value Type: STRING
input_raster_band_grouping False N/A See ENVIRASTER input type Provide the name of the band grouping to be used in the task, ie - panchromatic. -- Value Type: STRING
input_raster_filename False N/A See ENVIRASTER input type Provide the explicit relative raster filename that ENVI will open. This overrides any file lookup in the task runner. -- Value Type: STRING
index True N/A string Specify an array of strings representing the pre-defined spectral indices to apply to the input raster. -- Value Type: STRINGARRAY
output_raster_uri_filename False N/A string Specify a string with the fully-qualified path and filename for OUTPUT_RASTER. -- Value Type: STRING

Outputs

The following table lists all ENVI_SpectralIndices outputs.
Mandatory (optional) settings are listed as Required = True (Required = False).

Name Required Default Valid Values Description
task_meta_data False N/A directory GBDX Option. Output location for task meta data such as execution log and output JSON
output_raster_uri True N/A directory Output for OUTPUT_RASTER. -- Value Type: ENVIURI

Output structure

The output_raster_uri file will be written to the specified S3 Customer Account Location.

Background

For additional background information on this task please refer to the Harris Geospatial ENVI documentation and
ENVI® Spectral Indices.

Contact

If you have any questions or issues with this task, please contact gbdx-support@digitalglobe.com.

ENVI® Spectral Indices

This task creates a spectral index raster with one or more bands, where each band represents a different spectral index. Spectral indices are combinations of surface reflectance at two or more wavelengths that indicate relative abundance of features of interest. Vegetation indices are the most popular type, but other indices are available for burned areas, man-made (built-up) features, water, and geologic features.

GBDX Registered Name: ENVI_SpectralIndices
Provider: Harris Geospatial Solutions