1 The Sentinel Toolbox
The Sentinel Toolbox consists of 3 separate applications:
Sentinel-1 Toolbox (SAR applications)
Sentinel-2 Toolbox (High resolution optical applications)
And Sentinel-3 Toolbox (High resolution optical applications)
Sentinel-2 has become the gold standard for open satellite data. In order to process the vast amounts of data collected by Sentinel-2A/2B, users can use the Sentinel Toolbox. One of the highlights of the Sen2cor plugin which allows users to correct for atmospheric effects and classify images.
If you download Sentinel-1 synthetic aperture radar data, you can process your data with the Sentinel-1 toolbox. For example, you can perform interferometry, speckle filtering and coregistration.
For your assistance, the open STEP Forum is a vibrant community of remote sensing enthusiasts to help answer questions you have.
2 QGIS Semi-automatic Classification Plugin (SCP)
QGIS is one of the most powerful open source GIS softwarepackages available for free… And plugins are the key its success.
In terms of remote sensing plugins, the semi-automatic classification plugin offers the most practical solution for optical images.
Because you can download Sentinel, Landsat, ASTER and MODIS imagery directly using the plugin, this feature makes the plugin most convenient for is supervised image classification.
Furthermore, it also provides tools to its pre- and post-processing of imagery. No wonder why it’s in the top 5 downloaded plugins for QGIS.
3 SAGA GIS: System for Automated Geoscientific Analyses
SAGA GIS is ideal for most remote sensing needs because of its rich library grid, imagery and terrain processing modules.
In terms of classification, it has your basic supervised but it’s not as intuitive and user-friendly as other remote sensing software. For analyses and manipulation, it flourishes with terrain tools like TPI, TWI and soil classification. It also has some rudimentary tools for photogrammetry and support vector machine (SVM).
Although it has a vast library of raster-based tools, the only downfall of SAGA GIS is the lack of documentation for some of them.
4 ORFEO Toolbox (OTB): Optical and Radar Federated Earth Observation
The ORFEO toolbox was a cooperative project developed by France and Italy primarily built on the shoulders of the open source community.
This image processing library specifically aims at high spatial resolution data. ORFEO provides a wide range of remote sensing functions including radiometry, PCA, change detection, pan sharpening, image segmentation, classification and filtering.
One really interesting aspect of this software is the capability to do Large-Scale Mean-Shift segmentation (LSMC). This type of object based image analysis is a rare feature seen in software nowadays.
5 GRASS: Geographic Resources Analysis Support System
GRASS GIS is full of functionality. For example, it offers image classification, PCA, edge detection, radiometric corrections, 3D, geostatistics analysis and filtering options.
Another key feature of GRASS is the LiDAR processing and analysis. You can filter LiDAR points, create contours and generate DEMs. Next time you see a LAS file, see what GRASS can do with it.
For synthetic aperture radar, you may want to look intoPolSARPro. This software can handle dual and full polarization SAR from ENVISAT-ASAR, ALOS-PALSAR, RADARSAT-2 and TerraSAR-X.
There’s a wide range of tools like importing, conversion, filtering, decompositions, inSAR processing and calibration. Another neat part of this software is the graph processing framework where users can automate workflow. This functionality is similar to ArcGIS model builder and easy to set up.
Overall, PolSARPro is a very sophisticated piece of open source remote sensing software. You need to take a look at PolSARPro if you’re working with full or dual polarization SAR data.
The neat part about Opticks software is the long list of extensions you can add. There are plugins for raster math, radar processing and hyper/multispectral.
Before downloading an extension, make sure to check the compatibility. Actually, you might have to scale back your Opticks version in order for the extension to work properly
8 OSSIM: Open Source Software Image Map
Not only has it been actively developed for almost two decades but interesting enough, it’s being funded through US departments such as in intelligence and defense.
OSSIM is a high performance open source remote sensing software application. Some of the key features is compatibility with more than 100 raster and vector formats and over 4000 different projections and datums.
It supports a long list of sensors but some may require additional plug-ins. If you need some remote sensing direction for high spatial resolution imagery, OSSIM might be the answer you have been searching for.
InterImage is a bit different from the other open source remote sensing software on this list. It specializes in automatic image interpretation, which is pretty neat.
The core theme of automatic image interpretation is object-based image analysis (OBIA). This involves segmentation, exploring their spectral, geometric and spatial properties and then classification.
Although InterImage was developed in Brazil, documentation is available in English.
10 ILWIS: Integrated Land and Water Information System
For more than 25 year, ILWIS has been used from GIS enthusiasts. Actually, since its first release it has over 27,000 downloads. But it wasn’t until recently that it has become available for public use.
It is equipped with stereoscopy and anaglyph tools to create stereo pairs from two aerial photographs. Alternatively, if you have satellite data, ILWIS has image classification techniques to create land cover classes.
ILWIS was originally built for researchers and students. For this reason, effort was concentrated on developing a user-friendly environment.
gvSIG is known for its wide variety of rich features. And this applies to its remote sensing capabilities too. For example, users can perform supervised classification, band algebra and decision trees.
On top of that, gvSIG software delivers a more diverse range of tools like Tassled Cap which is ideal for monitoring vegetation health/vigor and urban growth. Further to this, the vegetation indices toolbar analyzes chlorophyll and plant health, if you have multispectral data.
12 Whitebox GAT
There’s a hydrology theme that surrounds Whitebox GAT because it actually replaced Terrain Analysis System (TAS) – an Esri tool for hydro-geomorphic applications.
Where it shines is LIDAR! It’s like the swiss-army knife of LiDAR data with even a tool that can convert it to shape file. Although the cartographic tools are bare, overall Whitebox GAT has a solid 410 tools for all your GIS needs.
E-foto is the digital photogrammetry specialist in the group of open source remote sensing software. The core functionality is photo triangulation, stereoscopic modeling, digital elevation model extraction and terrain correction.
This software provides a fully functional photogrammetry tool set to use at no cost. E-foto has loads of tutorials and examples to get you well on your way to being a photogrammetry expert.