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


Jul
24
comment Are latitude and longitude independent of each other or correlated?
This question totally depends on the movement of the GPS device, not on longitude/latitude per se - surely you want to know about the actual space in which the thing is moving, longitude/latitude are just one way to represent that. (See the "Moving objects, trajectories" section in this CRAN Task View for a few pointers to software in R: cran.at.r-project.org/web/views/SpatioTemporal.html) KDE is a poor way to handle noise in tracks imo, how to deal with the temporal dimension and serial autocorrelation? Also, use map projections for a real world space rather than ellipsoid angles.
Jul
24
comment Are latitude and longitude independent of each other or correlated?
There is a clear difference in the distribution of longitude for a given latitude. (If you are near a pole you barely need to know the longitude compared to other places).
Jul
20
comment Generating polygons with shared boundaries using QGIS?
Surely qgis has a suite of snap-to controls. That would do it wouldn't it?
Jul
19
comment NAs not allowed error message in attempt to plot raster object in R
Please show all the code used. Can you point to an example file.
Jul
3
comment Conversion problem of projection of MODIS LAI from sinusoidal to geographic
I understand, I just think you have a job to do but this is a distraction. If this is the job, confirm the source crs is right and then use projectRaster to transform to the target crs. What is projection(lai_real) directly after you load it with raster?
Jul
3
comment Conversion problem of projection of MODIS LAI from sinusoidal to geographic
projection()<- assigns a crs, it does not do the transformation. Do you really need to warp this yhing or do you just want to extract from it?
Jul
2
comment Which projected coordinate system should be used for mapping the US?
colorado.edu/geography/gcraft/notes/mapproj/mapproj_f.html andhttp://www.georeference.org/doc/guide_to_selecting_map_projections.htm
Jun
29
comment How to exactly georeference in QGIS
More details please.
Jun
26
comment Processing HDF4 data in R
HDF4 can be built into rgdal by building it into GDAL, it's not straightforward: scigeo.org/articles/…
Jun
25
comment Map project a raster having separate latitude and longitude raster bands
My email is in my profile. Send a link to the original source rather than the file if possible
Jun
25
comment R plot raster with real colors
Use raster or brick on the file name, not via rgdal. If it is a palette raster() and plot will work, if rgb then brick and plotRGB will work.
Jun
25
comment Map project a raster having separate latitude and longitude raster bands
Can you point to a specific file? I am keen to check it out
Jun
25
comment Map project a raster having separate latitude and longitude raster bands
gdal has built-in support for this, though my experience is limited. See here for an example: lists.osgeo.org/pipermail/gdal-dev/2012-February/031756.html I also think gdalwarp infile outfile.tif will do something.
Jun
24
comment Dem file in .adf format, while .tiff is needed
In GDAL it is not the extension that defines the output format. GTiff is the default
Jun
22
comment R plot raster with real colors
We need to what raster source is referenced by thay VRT. It may be rgb or palette but no point in us guessing.
Jun
22
comment R plot raster with real colors
Show some code! Use ?brick and ?plotRGB. We can only guess what your actual problem is
Jun
19
comment How to compute the outline of multiple tracks?
alpha shapes / hull
Jun
17
comment Error in which.max() : not yet implemented for large objects in R
Decompose the problem into manageable sub-tasks and implement those. You want a single layer where each pixel value is the layer number with the max value of that pixel? The raster package has many ways to do that. At most brute you can just loop over seq_len(ncell(r[[1]])) and use extract with base::which.max to get the layer for each pixel.
Jun
12
answered Creating a loop for Lines data (spatial data)
Jun
11
comment How do I convert a VMAP to a shapefile using GDAL?
Can you explain what VMAP is and point to an example? Why do you want a shapefile and can that substantially represent the source? What does ogrinfo report on the source data?