diff --git a/doc/MUG.md b/doc/MUG.md index 85ec775..143ed74 100644 --- a/doc/MUG.md +++ b/doc/MUG.md @@ -68,6 +68,7 @@ configurations exist. - The data component contains the raster tiles forming the MRF, which themselves contain data values for each pixel. As opposed to the index, there is no guaranteed order of the data tiles within the data file. The data file is modified only by appending at the end of the file, all existing content will continue to take space on disk, even if it was replaced and is no longer accessible via the MRF driver. + The data file name may have a variety of extensions (e.g. ".ppg" for PNG tiles or ".pjg" for JPEG tiles). Note that there is no redundancy of information, neither of the components contain any information which exist in a different component of the same MRF. All three components are required for accessing the MRF content. It is not usually possible to fully recover the dataset from diff --git a/spec/mrf_spec.md b/spec/mrf_spec.md deleted file mode 100644 index 03dd80e..0000000 --- a/spec/mrf_spec.md +++ /dev/null @@ -1,57 +0,0 @@ -## Meta Raster Format (MRF) Specification v1.0.0 - -The Meta Raster Format (MRF) is an image and data storage format designed for fast access to imagery within a georeferenced tile pyramid at discrete resolutions. - -![](pyramids.png?raw=true) - -The format supports extremely large, tiled, multi-resolution and multi-spectral data. Sparse raster data is supported efficiently. JPEG (lossy) and PNG (lossless) compression per tile are currently supported. Grayscale, color, indexed (palette) color models are supported. - -The file format was originally developed at the NASA Jet Propulsion Laboratory. - -MRF is composed of metadata, data, and index files with the respective extensions: .mrf, .ppg/.pjg, and .idx. - -### MRF metadata file (.mrf) - -Header XML metadata file containing descriptive information about imagery for use with GDAL routines. All tiles store the same set of metadata. - - MRF_META: root node - Raster: image metadata - Size: size of overview - Compression: JPEG, PNG, PPNG (Paletted-PNG) - Quality: image quality - PageSize: dimension of tiles - Rsets: single image or uniform scaling factor - GeoTags: - BoundingBox: bounding box for imagery - -Additional custom elements are used with mod_onearth. - -Example: - - - - - PPNG - - 85 - - - - - - - - -### MRF data file (.ppg/.pjg) - -The Pile of PNGs (ppg) or Pile of JPEGS (pjg) data file contains blocks of concatenated images. Each block is a self-contained image that is either PNG or JPEG. The full resolution base of the pyramid is first, followed by any subsequent pyramid levels. The data file eliminates the need to store tiles in independent files, thereby minimizing file system operations and significantly improving performance. - -RGB and indexed colors are supported. Modifications to the file are done only via appends. With mod_onearth, the file starts with an empty tile. - -![](tiledata.png?raw=true) - -### MRF index file (.idx) - -The index file contains spatially organized pointers to individual tiles in an MRF (ppg/pjg) data file. Tiles are referenced by offset within the data file and size of the tile (both 64-bit integers). Tiles have a top-left origin. The index is fixed-sized and updated as tiles are modified. - -![](tileidx.png?raw=true) diff --git a/spec/pyramids.png b/spec/pyramids.png deleted file mode 100644 index c693935..0000000 Binary files a/spec/pyramids.png and /dev/null differ diff --git a/spec/tiledata.png b/spec/tiledata.png deleted file mode 100644 index 4c060df..0000000 Binary files a/spec/tiledata.png and /dev/null differ diff --git a/spec/tileidx.png b/spec/tileidx.png deleted file mode 100644 index c6b5153..0000000 Binary files a/spec/tileidx.png and /dev/null differ