Welcome to the Gridfour Project Notes page!

Although we are just getting started, we've added articles on using the new Grifour toolkit and GVRS Raster File API. You may access content through the list of articles in the panel on the right side of this page.

• The articles on this page are intended to cover topics that are relevant to general investigators and developers, not just people who are using the Gridfour software. In addition to the articles listed on this page, we also provide information that is specific to the Gridfour implementation and our GVRS API on our wiki. Want to find out details about using our software? Check out the The Gridfour Wiki Page
• The How-To articles are intended to provide information to developers and users working with raster data. Some of them, such as the NetCDF article, address broader topics related to raster data in general. Others, focus specifically on Gridfour utilities.
• The GVRS articles provide an introduction to Gridfour's file-based API for managing large raster data sets. The GVRS Performance article describes the performance issues associated with the both the GVRS utility and the optional data compression techniques it provides. These articles offer insights that will help you use the GVRS and get the best results in your own applications.
• The data compression articles provide background information on the algorithms, techniques, and methods used for the Gridfour data compression functions. And, because it is only fair to give credit where credit is due, they also trace all the Gridfour techniques to their origins in the the published literature.
• The Elevation GeoTIFF articles discuss the U.S. Geological Survey's Cloud-Optimized GeoTIFF product and provide techniques and examples for using the open-source Apache Commons Imaging libary to extract data and create shaded-relief imagery from these files.
• The The GVRS File Format Specification provides details about the internal organization of a GVRS file. It also provides information on some of the concepts that are used by the GVRS implementation.

• The Articles
• Gridfour Raster Data Compression Algorithms
• What Entropy tells us about Data Compression, Part I: Concepts
• What Entropy tells us about Data Compression, Part II: Case Studies
• Lossless Compression for Floating-Point Data
• Lossless Compression for Raster Data using Optimal Predictors
• GVRS: A Fast, File-Based API for Managing Raster Data
• GVRS Performance
• Managing a Virtual Raster using a Tile-Cache Algorithm
• An Investigation using Gridfour for Image Processing, Storage, and Data Compression
• How to Read a NetCDF File
• Elevation GeoTIFFs, Part 1: Shaded-relief techniques
• Elevation GeoTIFFs, Part 2: Color, Land-Cover, and Surface Water
• The GVRS File Format Specification