The USC GIS Research Laboratory offers a number of online geographic applications and Web APIs. You have to register for the services, and you’ll get 5000 use credits. After those are used up, the services are free for non-profit and non-commercial enterprises, as long as you cite/reference their use somewhere. For commercial use, if you post an attribution to the service on your website, and also allow them to use your name/logo on their website, you can also use it for free; if not, you can also buy processing credits from them. See this page on usage costs for more info.
Archive for February, 2009 Page 2 of 2
The last in this series (parts one, two, three, and four). The previous applications have been primarily focused on remote sensing applications, but there are also a number of general purpose freeware GIS programs that include significant remote sensing analysis capabilities.
A powerful but often difficult to use GIS program. Quantum GIS is implementing an easier interface for GRASS’s capabilities. A Java version of GRASS (JGRASS) is being built on top of uDIG, but is concentrating on hydrogeological and geomorphological capabilities for now.
- Canonical component analysis (CCA)
- Color composite generation
- Edge detection
- Frequency filtering (Fourier, convolution matrices)
- Fourier and inverse fourier transformation
- Histogram stretching
- IHS transformation to RGB
- Image rectification (affine and polynomial transformations on raster and vector targets)
- Ortho photo rectification
- Principal component analysis (PCA)
- Radiometric corrections (Fourier)
- Resampling
- Resolution enhancement (with RGB/IHS)
- RGB to IHS transformation
- Texture oriented classification (sequential maximum a posteriori classification)
- Shape detection
- Supervised classification (training areas, maximum likelihood classification)
- Unsupervised classification (minimum distance clustering, maximum likelihood classification)
gvSIG is moving towards release of version 2.0, which will add a substantial number of remote sensing analysis functions. If you want to look at an early version, there’s a 1.9 alpha release available.
- Clipping of bands and data
- Export layers
- Save from view to raster file
- Color table and gradient edition
- No data values management
- Pixel process (filters)
- Color interpretation management
- Overview creation
- Enhanced radiometric
- Histogram
- Geolocation
- Raster reprojection
- Georeferencing
- Automatic vectorization
- Band algebra
- Region of Interest (ROI) definition
- Supervised classification
- Semi-supervised classification
- Decision tree
- Transformations
- Image fusion
- Mosaic
- Scatter diagram
- Image profiles
Integrated Land and Water Information System, formerly commercial software, now open source.
- Image enhancement (contrast, linear stretching)
- Filtering
- Band combination and compositing
- Band ratios and indices
- Georeferencing
- Multi-band statistics
- Principal component analysis
- Image arithmetic
- Image fusion (e.g. pan-sharpening)
- Image classification
A very strong terrain/DEM analysis program, but has other applications as well, including remote sensing.
- Contrast enhancement
- Filters
- Band histograms
- Correlation (covariance) matrix
- Scattergrams
- Band ratios and normalized indices (e.g. NDVI)
- Principal components analysis
- Multi-band merges
- Image training and classification
- Hyperspectral image analysis (AVIRIS)
- Image averaging
- Pan-sharpening
Not primarily a remote sensing application, but has some modules for grid manipulation, statistics and analysis that could be useful.
LANDSAT, SPOT, ERS-1 and NOAA/AVHRR Data input; Registration and Geometric Correction; Image Mosaic with gray level equalization; Image Enhancement by Histogram Manipulation; Spatial Filtering; IHS and Principal Components Transformations; Arithmetical Operations; Pixel Values Reading; Maximum-likelihood pixel-based classifier; Image Segmentation and Region Classifiers (Supervised and Unsupervised); LANDSAT and SPOT Images Restoration; Morphological Filters for Images; Mixture Models; Markov-based Techniques for Image Post-Classification; Radar Image Processing.
And if you want to create your own remote sensing analysis program, or add capabilities to a GIS, there’s the Orfeo Toolbox (OTB), an open-source library/API for image processing:
- image access: optimized read/write access for most of remote sensing image formats, meta-data access, simple visualization;
- sensor geometry: sensor models, cartographic projections;
- radiometry: atmospheric corrections, vegetation indices;
- filtering: blurring, denoising, enhancement;
- fusion: image pansharpening;
- feature extraction: interest points, alignments, lines;
- image segmentation: region growing, watershed, level sets;
- classification: K-means, SVM, Markov random fields;
- change detection.
A while back, I covered a web app that lets you color in countries on a world map, then download the resulting graphic. Since then, it’s added more features, including the ability to add text, lines and labels. Mike Piaget writes to tell me of a similar app he’s created, the Customizable Map Of The World. Not as many options as the other app, but easier to use:
Click on a color next to the country name, then click “Update Map Colors” to color the country on the map; here, I’ve colored all world countries that start with the letter “A”. There’s only six colors available for country colors (including the default), plus one for water, but you can modify those colors with the appropriate hex code at upper right. To save a copy of the map to your computer, right-click on the image and choose the “Save Picture As ..” option (or the equivalent in your browser):
Unfortunately, you’re limited to the single on-screen size; however, there are closeup maps available for the subregions Africa, Europe, Asia, the Middle East and South America (links at the bottom of the web app page).
A few months ago, Google discontinued Google Earth Plus, their $20/year augmented version of Google Earth. At the time, they said they would add one of Plus’s key features, support for direct connection of a GPS receiver, to the free version in the near future. With this week’s release of Google Earth 5.0, lots of attention has been paid to its big new features (ocean coverage, historic imagery, tour recording); see Ogle Earth and the Google Earth blog for more info on those. But I’ve only seen one or two mentions that this latest version adds GPS support.
Access the GPS control with Tools => GPS:
The Historical tab lets you import waypoints, tracks and routes from either a Garmin or Magellan GPS (the only brands currently supported). Garmin support should include the serial as well as USB interfaces, but I don’t have a serial connection to test that. Checking the “Create clickable image …” link assigns icons to the track/route points with pop-up data for them; checking the box below that creates icons to show the direction of movement.
The Realtime tab shows the options for live tracking of your position in Google Earth:
Currently, it supports only the Garmin protocol and NMEA (serial connection, either through a serial port or Bluetooth); I’ve tried both, and it does a good job of finding the correct port. Polling interval determines how often GE gets position data from your GPS, while “Track point import limit” determines how many position points are imported and averaged for every polling. More points means a slower position update, but a more accurate one; less points updates your position more quickly, but potentially at the cost of accuracy. If you have a high-quality GPS receiver, with strong satellite reception, accuracy is unlikely to be a serious issue, and you can probably set the track point import limit to a low number.
Checking the “Automatically follow the path” box will make Google Earth automatically zoom to the current GPS location, and follow it as it changes. The only view you have with this option is from overhead; if you change to an oblique view, it will automatically move the view back to overhead. The option is ghosted out as soon as you start tracking, so if you don’t check the box, the only way to immediately zoom to the current GPS position is to go into “Temporary Places”, find the Position marker in the RealTime GPS folder, and double-click on it:
If you move, it also saves your path and displays it onscreen; to save it permanently when you’re done, you’ll have to right-click on the “Path” listing and save it as a KML file. I believe the Position icon is supposed to show up in the Google Earth display to show your current position, but for static positions it disappears almost immediately.
For simplicity and convenience, Google Earth’s built-in GPS interface is hard to beat. But for real-time tracking, the feature set is pretty weak; the limited GPS receiver support, the inability to view from an oblique angle with live tracking, and problems with icon display (and lack of choice for the icon) are serious drawbacks. The data import feature also isn’t that great; you’d be better off using a program like EasyGPS or GPSTrackmaker to import data from your GPS, and then save it either in GPX format (which Google Earth can open), or directly in KML format. The free version of GPS Trackmaker comes with a real-time GPS position interface which supports more units than Google Earth, and which can plot your rea-time position in Google Earth. There are other options for GPS real-time tracking and data import into Google Earth as well; do a search on this blog for “Google Earth” and “GPS”.
A while back, I covered the World Names Profiler, a program for plotting the population density for surnames for countries around the world. Dynastree Maps is a similar application for the US, Canada, and Germany, and includes additional information:
Note: Currently only works in Internet Explorer and Safari. I also get a Javascript error message, but it doesn’t seem to affect functionality.
