ENVI1 Basic Function Overview

Broto Raharjo2

1. Tutorial cited in literatures is using ENVI 3.1, this paper is using ENVI 4.0 while latest version is ENVI 4.42. GIS Engineer ESRI South Asia Indonesia Office Atrium Mulia 3rd Floor #305 Jl. H. R. Rasuna Said Kav B10-11 Jakarta 12910, Indonesia Phone 61 21 527 1023 Email braharjo@esrisa.com

Read Any Imagery Type and FormatSupports imagery types from numerous satellite and airborne sensors including panchromatic, multispectral, hyperspectral, radar, thermal, lidar, and more. Can read over 70 data formats and includes HDF, GeoTIFF and JITC certified NITF support.

Prepare ImageryProvides automated pre-processing tools that allow to quickly and easily preparing imagery for viewing or additional analysis. • Orthorectify imagery• Register two or more images• Calibrate imagery• Correct imagery for atmospheric distortions• Create vector overlays• Identify regions of interest (ROIs)• Create digital elevation models (DEMs)• Perform pan sharpening, masking, and mosaicking• Resize, rotate, or convert the data type

Explore ImageryGives an intuitive user interface and easy-to-use tools that allow to quickly and easily view and explore imagery. Can view large datasets and metadata, visually compare imagery, create powerful 3D visualizations, create scatter plots, explore pixel signatures, and more.

Analyze ImageryProvides the industry-leading image processing functionality need to extract information for research, intelligence or planning purposes.

Data Analysis Tools• Create geospatial statistics such as autocorrelation and semi-variance• Calculate image statistics such as mean, min/max, standard deviation• Extract linear features• Synthesize radar imagery• Calculate principal components• Detect change• Measure features• Model topopgraphic characteristics• Apply common and user-defined filters• Perform custom band and spectral math functions

Spectral Analysis Tools• Classify using supervised and unsupervised methods• Identify spectral signatures• Detect and identify targets• Identify features of interest• Analyze & map materials of interest• Perform whole-pixel and sub-pixel analyses• Use a suite of post classification tools to refine your results• Calculate forest health with vegetation analysis tools

Share InformationProcessed image can be output to common vector and raster formats for collaboration and presentation.

Customize Geospatial Image ApplicationBuilt on a powerful development language, IDL, allowing its features and functionality to be easily extended or customized to fit your specific application. Allows to create batch processes, customize menus, add algorithms and tools, integrate C++ and Java code.

ENVI Main Menu

IDL User Interface to write user functions and scripts in the IDL programming language to customise ENVI.

Opening Images

Image query

Image query

Image query

Contrast stretching

Image band comparisons: Scatter plots

When position the cursor over water, points in the bottom left corner of the scatter plot are highlighted (blue region). Position the cursor over the urban areas yellow region are highlighted. Move the cursor over vegetation green region are highlighted.

Regions of Interest: ROI's

Regions of Interest: ROI's

Image annotation

Save and output images

SOURCE CITED

ITT Visual Information Solutions http://www.ittvis.com/envi/

Ministry of Science and Technology, Brazilhttp://www.ltid.inpe.br/tutorial/tut_i.htm

Virtual Laboratory for GIS and RS, Hongkong Baptist Universityhttp://geog.hkbu.edu.hk/virtuallabs/rs/rs.htm