[R-sig-Geo] raster package and tiling schemes

[Michael Sumner]

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

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