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| GRASS's long-standing raster format is overdue for a major overhaul.<BR>
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| Below you will find some ideas and roadmaps for future work.<BR>
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| The idea of this page is to collect ideas and flesh out a
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| specification so that when the change occurs, all the
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| components will be in place, pitfalls expected, and
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| the implimentation, when it comes, quick and painless. Most
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| importanly it can serve to keep interested parties informed
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| and working together instead of in parallel forks.<BR>
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| Any changes to the data format will necessitate a bump in
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| major version number (i.e. from GRASS 6 to GRASS 7) so if
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| possible changes should happen in the same development cycle,
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| and relatively minor changes should be held back in
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| experimental status until a major change is committed.
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| __TOC__
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| see also [[GRASS 7 ideas collection#Raster]]
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| ==== Core raster format ====
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| ''Lead developer: Glynn Clements''
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| * Storage in tiles instead of by row.
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| ** Reasoning: Glynn said on the mailing list: "In most cases, single-level tiled storage will give you close to the same performance with a lot less complexity."
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| ** Function needed to check whether tiles are all null, or all the same value.
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| ** What tile size should be used? Could be user/program specified, or standard value of something like 64x64. If there isn't a fixed value then there should be utility program that can convert tiled rasters to different tile sizes. - [[User:Ferrouswheel|Ferrouswheel]]
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| * Merge NULL file into main data array.
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| ==== Directory structure ====
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| * Centralize map components in "<tt>$MAPSET/raster/$MAPNAME/*</tt>" instead of many "<tt>$MAPSET/cell/$MAPNAME</tt>", etc. directories.
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| Many library functions and modules will need to be updated.
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| The GRASS 6 vector format has already been ported to this structure.
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| * demo 2-way conversion scripts: [http://wald.intevation.org/tracker/index.php?func=detail&aid=372&group_id=21&atid=205 Gforge patch #372]
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| ==== Meta-data support ====
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| The existing raster meta-data handling is rather weak.
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| (currently stored in <tt>$MAPSET/hist/$MAPNAME</tt>)
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| Total replacement will be the best option.
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| Brad Douglas suggests:
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| ''It would be very advantageous to at least support metadata as specified
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| in [http://www.fgdc.gov/standards/projects/FGDC-standards-projects/csdgm_rs_ex/MetadataRemoteSensingExtens.pdf FGDC-STD-012-2002].
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| XML is an ideal file format.''
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| Nick Lawrence suggests:
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| The GIMP project is examining the concept of a general mult-layer bitmap format.
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| [http://create.freedesktop.org/wiki/index.php/General_multilayered_bitmap_exchange_format OpenRaster - Create Wiki]
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| [http://pippin.gimp.org/OpenRaster/ OpenRaster Sandbox]
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| ==== Recent discussions ====
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| * http://www.nabble.com/-GRASS5--Raster-files-suggestion%3A-new-directory-layout-td8588651.html
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| * http://lists.osgeo.org/pipermail/grass-dev/2008-April/036994.html
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| * http://lists.osgeo.org/pipermail/grass-dev/2008-April/037578.html
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| Other suggestions:
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| * [[Time series in GRASS]] support
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| [[Category:Development]]
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