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bio website staff.acecrc.org.au/~mdsumner
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visits member for 4 years, 7 months
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R, Manifold, GDAL, also interested in Python, topojson/D3 and NetCDF/HDF


16h
comment rgdal with multiple Feature Datasets in R
When you say "others get" are they using the same R and rgdal versions and are you sure it's the same data source?
1d
comment Getting warning when opening NetCDF file using gdal?
the file is this one: oceandata.sci.gsfc.nasa.gov/cgi/getfile/… available here oceandata.sci.gsfc.nasa.gov/MODISA/L2/2015/069 via navigation from oceandata.sci.gsfc.nasa.gov
1d
comment Getting warning when opening NetCDF file using gdal?
This is one for the gdal-devs, point them to details about the format change to netcdf4: oceancolor.gsfc.nasa.gov/DOCS/FormatChange.html Possibly also this exchange could give you some clues, but I'm not hopeful about it: lists.osgeo.org/pipermail/gdal-dev/2015-February/040973.html
Jun
26
comment What coordinate data could this ASCII file represent?
Always. Reproducibility is the aspirational standard.
Jun
26
comment What coordinate data could this ASCII file represent?
No information means no information I'm afraid. Until you get a nice picture there's no way to be sure.
Jun
26
comment Raster alignment terminology?
I would say that if they share the same resolution, alignment, offset, scale and coordinate system then they are the same raster.
Jun
25
comment Creating a new raster layer based on mean of other raster layers, ignoring NA values in R
Well you must not be using this code I guess. Can you provide useable code? Don't use "mean" as a variable name either, it's already a function.
Jun
25
comment Creating a new raster layer based on mean of other raster layers, ignoring NA values in R
What package provides an overlay method for numeric?
Jun
25
comment Heatmap on globe - distortion problems
(If anyone wants to explore this in R I recreate it here, requires a github package plus CRAN ones: gist.github.com/mdsumner/a3d2277bae7cd8082302)
Jun
21
comment Different kinds of time+spatial data
Pebesma has a paper on this: cran.r-project.org/web/packages/spacetime/vignettes/jss816.pdf It's easy to overcook your own defs though, in ways that don't actually work for others
Jun
19
comment What raster-based GIS systems really work?
R's raster package totally kicks serious raster butt, it's not perfect but there's nothing better.
Jun
14
comment Equal Area Projection for Indonesia - Standard Parallels
The standard parallels are where "true scale" lies, and to the north and south distortion increases. Putting them nearer to the centre means that more of the central region is "optimal". Also, see this for conic discussoin generally en.wikisource.org/wiki/The_American_Practical_Navigator/…
Jun
14
comment Grid-type shapefile from raster GeoTIFF
rasterToContours in the R package raster returns cell edges in a SpatialLinesDataFrame.
Jun
14
comment What projection to use for many parts of the world
Is your poster wrapped around a globe?
Jun
13
comment Georeferencing reversal of image
What software are you using? What steps did you take, in detail?
Jun
13
comment Processing large amounts of Rasters in R
I think the call is ok, you just want to assign it somewhere, .i.e. winterSumRaster <- .
Jun
12
comment Processing large amounts of Rasters in R
setValues(winterSumRaster,getValues(dailyRaster)) - this is not actually persisted anywhere since there's no assigment
Jun
12
comment Why does @data@values slot for RasterLayer only contain logical(0) and not the actual values?
Don't use @ unless you are developing internal code - use readAll(NDVI). It happens as a memory-efficiency technique, you can open very large grids as kind of a promise - raster promises to pull in the data (via rgdal, via GDAL in this case) when you actually need the numbers. If you need to save the object as a standalone R object not tied to a file readAll is the way to do it. See ?raster "In many cases . . . does (initially) not contain any cell (pixel) values in (RAM)"
May
30
comment How to modify or create a wider UTM zone?
Don't do it! Mercator is suited to narrow areas that are parallel to a particular great circle. Use a projection that suits your area. The internet is retarded on this topic.
May
25
comment GDAL doesnot support HDF4 e
Can you check that GDAL has the driver, then maybe it's Python not picking it up properly? Using the gdal-bin that you installed use: gdalinfo --formats | grep HDF4 Other than that it might be a python special thing, dunno