raster package and tiling schemes
On Thu, 21 Jan 2016 at 04:00 Alex Mandel <tech_dev at wildintellect.com> wrote:
On 01/19/2016 09:22 PM, Michael Sumner wrote:
Hi there, does raster or any related package have any built-in schemes that allow for easy management of tiles? Raster itself provides a very powerful platform for building such a
scheme,
since we can reasonably easily reclassify analogous RasterLayers at different resolutions, and map cell values from one raster to another - being careful with tile overlaps and alignment of course. Anyone working on such a thing already, or got any grand plans? I know rgdal and friends provide access to the GDAL tools in various
ways,
but I want something in R only. Cheers, Mike
What's the goal of tiling? And when you say tiles do you mean multiple zoom levels like web tiles, or more a raster catalog like a VRT of multiple rasters next to each other? If you mean zoom levels, things like pyramids in tiffs are local equivalent but that's only for viewing data, not really useful for analysis. If you mean things that are adjacent to each other, I would assume that if they aren't all the same resolution/scale then you need to go to the lowest common denominator and resample everything to that to get a seamless data set. In this case the Raster merge and mosaic functions. Though if you want to keep the files in pieces, save them all out into the same resolution/scale, clipped to no longer have overlap, and gdal_buildvrt. Or am I missing the point?
Thanks Alex, these are good questions. I just want to be able to do it arbitrarily for lots of reasons, but right now I want to tile up some global data sets and allow my code to access them from a website at different resolutions. Basic stuff. Stuff that should be basic and on hand. The machinery behind raster::getData is probably a good place to start, to augment the SRTM with non-land areas. I'll get to it, but keen to hear of alternatives. (It's kind of amazing that there's still no comprehensive global source for bathymetry/topography data as a service.) Cheers, Mike -Alex
Dr. Michael Sumner Software and Database Engineer Australian Antarctic Division 203 Channel Highway Kingston Tasmania 7050 Australia [[alternative HTML version deleted]]