GBDX

ENVI® Spectral Index

This task creates a spectral index raster from one pre-defined spectral index. Spectral indices are combinations of surface reflectance at two or more wavelengths that indicate relative abundance of features of interest. The Normalized Difference Vegetation Index (NDVI) is an example.

GBDX Registered Name: ENVI_SpectralIndex
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.

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

tasks = []
output_location = 'ENVI/SpectralIndex'

# 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_ndvi = gbdx.Task("ENVI_SpectralIndex")
envi_ndvi.inputs.input_raster = aop.outputs.data.value
envi_ndvi.inputs.index = "Normalized Difference Vegetation Index"
tasks += [envi_ndvi]

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

workflow.execute()

Inputs

The following table lists all ENVI_SpectralIndex 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 a string representing the pre-defined spectral index to apply to the input raster. -- Value Type: STRING
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_SpectralIndex 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 Index.

Contact

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

ENVI® Spectral Index

This task creates a spectral index raster from one pre-defined spectral index. Spectral indices are combinations of surface reflectance at two or more wavelengths that indicate relative abundance of features of interest. The Normalized Difference Vegetation Index (NDVI) is an example.

GBDX Registered Name: ENVI_SpectralIndex
Provider: Harris Geospatial Solutions