Spatial

Create Raster Image Mosaic

When working with raster data such as satellite imagery, it is sometimes necessary to combine multiple adjacent, possibly overlapping smaller rasters into a single large raster that covers the entire area of interest. This example demonstrates one way to use R to create a raster image mosaic while also applying a resampling algorithm to align the inputs.

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Resample Raster Images

This example demonstrates two R programming techniques for resampling (changing the cell size or spatial resolution) of a raster satellite image. The first technique uses data objects and methods from the sp package. The second technique uses the recently released (Fall, 2009) raster package.

We resample the same satellite image, and compare the results of all sampling methods by computing elementary statistics.

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Generate Region Of Interest (ROI) Polygons for Point Data With R

This case presents an R script that: 1) Reads and displays in an outline map ESRI point and polygon Shape Files for a three-county Central California region; 2) demonstrates two different R programming methods for generating the Convex Hulls bounding the polygons 'belonging' to each county, 3) calculates the areas of each county and Convex Hull polygon.

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Read and Display Data from GPS Devices Using R

Two examples demonstrate the use of the R environment to process data sets from GPS devices:

  1. Read, transform, and display point and track data stored in industry-standard GPS Exchange (GPX) format using the readGPS()function, from the maptools package.
  2. Translate point data in proprietary format, collected with a Trimble GPS Receiver, into a cross-platform ASCII output file. During processing, apply Differential Correction to the point set, using Trimble-supplied software.

Both examples use methods from the sp and maptools packages.

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