Dear All,

I was trying to download MODIS Aerosol data and extract values for a given
latitude and longitude.  I am not familiar with the  HDF file format. I am
trying to familiarize myself with it and started playing with the codes on
http://www.r-gis.net/?q=ModisDownload. I downloaded the example_1.r file
and run it. I have downloaded RTM and run the code. While running I got the
error  "Mosaic failed!". Is there anything I should do ? Or do you have an
advice for me on how to read MODIS aerosol data and extract values for a
given lat/lon. I also would like to extract other values like water column
, albedo and etc from MODIS. I really appreciate your help on this.

Best regards,

Alemu


On Wed, Aug 8, 2012 at 8:32 AM, Jan Verbesselt <janverbesselt@gmail.com>wrote:

> Hi Thiago,
>
> one way is to:
> first
>
> rr2 <- resample(r2)  ## assuming the pixels with 1 are the ones you want to
> select and with NA you do not want to select
>
> sr1 <- rr2 * r1 ## and then multiple both rasters
>
> There are other options too probably via the extract() function etc.
>
> Cheers,
> Jan
>
>
> On Wed, Aug 8, 2012 at 3:17 PM, Thiago Veloso <thi_veloso@yahoo.com.br
> >wrote:
>
> >  Dear all,
> >
> >  I have two rasters: r1 is a 0.5 degree netcdf file produced by a
> > vegetation model. r2 is a 30m shapefile which I rasterized to a raster
> with
> > the same 30m resolution. r2 values are all NA and 1.
> >
> >  Please see below:
> >
> > > r1
> > class       : RasterLayer
> > dimensions  : 10, 18, 180  (nrow, ncol, ncell)
> > resolution  : 0.5, 0.5  (x, y)
> > extent      : -53, -44, -25, -20  (xmin, xmax, ymin, ymax)
> > coord. ref. : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
> > values      : in memory
> > layer name  : variable
> > zvar        : variable
> >
> > > r2
> > class       : RasterLayer
> > dimensions  : 14469, 22190, 321067110  (nrow, ncol, ncell)
> > resolution  : 0.0002702699, 0.0002702702  (x, y)
> > extent      : -52.60649, -46.6092, -23.7172, -19.80666  (xmin, xmax,
> ymin,
> > ymax)
> > coord. ref. : +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84
> > +towgs84=0,0,0
> > values      : in memory
> > layer name  : cs_2005spx1
> > min value   : 1
> > max value   : 1
> >
> >  Here you can see a join plot:
> > http://img855.imageshack.us/img855/2820/plotzoom.png
> >
> >  Is it possible to create a new raster, which is composed only by r1
> cells
> > which are "touched" by r2 cells?
> >
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
>
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>
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