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bio website staff.acecrc.org.au/~mdsumner
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visits member for 3 years, 5 months
seen 4 hours ago

R, Manifold, GDAL, also interested in Python, topojson/D3 and NetCDF/HDF


1d
comment RasterStack extract() for duplicated dates
just use sub <- subset(temp, 18263:23011) and then (admittedly I don't know what should happen here, sp can be overly prescriptive) use your second line as you did. I suspect your -99 thing is due to a problem with the coordinates themselves, but you don't provide enough info here.
1d
comment RasterStack extract() for duplicated dates
What is temp@layers? You should not be using the @ operator btw, where did this code come from?
2d
comment How do I peform a true GIS Clip of polygons layer using a polygon layer in R
Try gIntersection with byid=TRUE (I think it's a problem with dangling topologies for certain clips, and sometimes doing it this way helps), for speed check out gUnarySTRtreeQuery() or gBinarySTRtreeQuery() to identify intersecting bounding boxes of pairs of polygons and only intersect those pairs. There's no easy high-level wrappers for all of this afaik
2d
comment Mapnik: GeoTIFF flipped (mirrored vertically)
I would figure out why it's coming out positive from QGIS, it can be tricky to track down where the interpretations are applied in a workflow like this, we need a reproducible example
Apr
11
comment Mapnik: GeoTIFF flipped (mirrored vertically)
Y pixel size would usually be negative in test.tif, not all tools will apply the transform correctly without that.
Apr
8
comment Extract Raster from Raster using Polygon shapefile in R
Use projectExtent() to get just the extent for cropping the raster.
Apr
8
comment Extract Raster from Raster using Polygon shapefile in R
extract() does perform on the fly reprojection, but crop() does not. That might account for some confusion
Apr
8
revised What programs would allow for the mapping of a geoid in 3d?
added 168 characters in body
Apr
8
answered What programs would allow for the mapping of a geoid in 3d?
Apr
2
answered R - color SpatialLines by attribute
Mar
26
comment How to create a time series with a NetCDF raster from Ensembles E-OBS using GDAL, R, GRASS GIS or SAGA GIS
In R, start with library(raster);(ncdata <- brick("file.nc")) and report back on what you get. You'll need either ncdf4 or ncdf packages also installed for raster to use.
Mar
25
revised What programs would allow for the mapping of a geoid in 3d?
fixed radius
Mar
25
revised What programs would allow for the mapping of a geoid in 3d?
updated to use delaunayn from geometry package
Mar
24
answered What programs would allow for the mapping of a geoid in 3d?
Mar
24
comment What programs would allow for the mapping of a geoid in 3d?
R's rgl could do this, can you add a link to the data and I will have a go.
Mar
23
comment Is it possible to render tile-based web mapping projects in any other projection than web mercator?
Yes of course it's possible, just use gdal2tiles it's really easy. Interoperability, not sure, but I don't see that it's really relevant. Mercator is a terrible projection, it's just a simple compromise for the entire globe in one plane. There's also longlat, Cylindrical Equal Area, Peters, and none are "very good" because they apply to the whole world, but they work in a narrow context for a purpose.
Mar
15
comment Making a georeferenced PDF or GeoTIFF from jpg+jgw using GDAL for Avenza PDF Maps
We can only guess at the problem with the information you have here
Mar
15
comment Making a georeferenced PDF or GeoTIFF from jpg+jgw using GDAL for Avenza PDF Maps
You can't, TFW is just the 6 figure affine transform. That is why you should use good feature-rich formats, not these ancient legacy hacks. We all need to demand better
Mar
10
comment Problem with MIF/MID allignment
"Some other software" is not descriptive enough for this site. You should describe exactly what you are using and the steps used.
Mar
10
comment I want to reproject data from 0-360 to -180 - 180
You can create a VRT data set to do the job: trac.osgeo.org/gdal/wiki/UserDocs/RasterProcTutorial