[GRASS-user] Geotiff files

Fri Aug 17 11:32:45 PDT 2012

Will do!!!

On Fri, Aug 17, 2012 at 11:33 AM, Micha Silver <micha at arava.co.il> wrote:

>  On 08/17/2012 09:25 PM, Pedro Camargo wrote:
>
>  Hi Micha,****
>
>                 ****
>
>                 Thanks for all the help!  ****
>
> ** **
>
> I was finally able to compute the statistics I needed. These were the
> steps I followed:****
>
>
>  Good to hear of your success. Cc'ing back to the GRASS list so others
> can follow.
>
>
>
>  ** **
>
> 1.       Downloaded the raster image from Cropspace (WGS84/Lag/long)****
>
> 2.       Imported  the raster image into GRASS****
>
> 3.       Imported the area vector layer from a Shape file****
>
> 4.       Added centroids to the shape file (v.centroids)****
>
> 5.       Converted the vector layer into raster (v.to.rast using attr as
> values)****
>
> 6.       Computed statistics for my raster layers using r.stats -c -a
> (gives me a table with the sums of each combination of values in both
> layers.  Filtering this database for each value found in the area layer, I
> have the statistics about the crop layer for each one of my areas****
>
> ** **
>
> ** **
>
> It worked beautifully, and the next step is to generate a batch/script
> file to extend the analysis to the whole country and multiple years
> (probably using Python, which I used before, or a DOS batch).****
>
> ** **
>
> ** **
>
> Thank you again,****
>
> ** **
>
>                 Pedro****
>
> ** **
>
> -----Original Message-----
> From: Micha Silver [mailto:micha at arava.co.il <micha at arava.co.il>]
> Sent: Wednesday, August 15, 2012 12:56 PM
> To: Pedro Camargo
> Subject: Re: [GRASS-user] Geotiff files
>
> ** **
>
> Hi Pedro****
>
> ** **
>
> On 08/15/2012 08:17 PM, Pedro Camargo wrote:****
>
> >** **
>
> > Hi Micha,****
>
> >** **
>
> >                   Thanks for your help. I was doing just like you ****
>
> > described in your instructions (very precise, btw), but I keep finding *
> ***
>
> > an error.  Is it possible that I’m working with a too big of a file?****
>
> > It is the whole state of California.****
>
> >** **
>
> ** **
>
> Yes that indeed could be the problem. To get a better idea of what you're
> dealin with:****
>
> ** **
>
> After you have imported the raster into GRASS, check what you get from
> g.region -p****
>
> ** **
>
> ( On the menu "Settings->Region->Set Region" and check to print in the
> Print tab). How many cells is the whole region?****
>
> ** **
>
> Next you can do r.univar -a ("Raster->Reports and Statistics->Univariate
> statistics" and in the Print tab check for Area totals). This will tell you
> how much total area for each category.****
>
> ** **
>
> ** **
>
> >                 If I may also ask, would it be easier just to compute **
> **
>
> > statistics (number of pixels of each value/category) for each area I’m *
> ***
>
> > interested in (Areas equivalent to Counties in the whole Country)?****
>
> >** **
>
> ** **
>
> Often the suggestion comes up to "think raster". THis might be the case
> here. You could work the other way, and covert the counties areas to a
> raster, then use it as a "zone" parameter to the r.univar command. This
> will give the univariate statistics for each category value in the counties
> raster. There's a good example in the r.univar manual page:  ****
>
> http://grass.osgeo.org/gdp/html_grass64/r.univar.html****
>
> ** **
>
> Maybe that will help.****
>
> ** **
>
> Cheers,****
>
> ** **
>
> Micha****
>
> ** **
>
> > Thanks for your help,****
>
> >** **
>
> > Pedro****
>
> >** **
>
> > *From:*Micha Silver [mailto:micha at arava.co.il]****
>
> > *Sent:* Wednesday, August 15, 2012 2:47 AM****
>
> > *To:* Pedro Camargo****
>
> > *Cc:* grass-user at lists.osgeo.org****
>
> > *Subject:* Re: [GRASS-user] Geotiff files****
>
> >** **
>
> > On 08/14/2012 08:36 PM, Pedro Camargo wrote:****
>
> >** **
>
> > Hi,****
>
> >       I'm new to Grass and to Raster files, and although I know some ***
> *
>
> > concepts, I'm having trouble to work with geotiff files. Basically, I **
> **
>
> > want to import tiff files downloaded from ****
>
> > http://nassgeodata.gmu.edu/CropScape/ into vector layers.****
>
> >** **
>
> > Any ideas on how can I do that?****
>
> >** **
>
> >** **
>
> > I downloaded a small section of the 2011 landcover layer from the site *
> ***
>
> > you linked to. In the download options, I specified WGS84 Lat/Lon ****
>
> > coordinate system. (Otherwise is was projected in an unknown, but ****
>
> > specified Albers Equal Area CRS). Then I imported the raster into a ****
>
> > Lat/Lon WGS84 LOCATION in GRASS using: r.in.gdal. No problem here:****
>
> > r.in.gdal in=NASS....tif out=nass****
>
> > # Or in the GUI, File->Import raster->Common import formats g.region ***
> *
>
> > -p rast=nass # Settings->Region->Set Region->Set to raster****
>
> >** **
>
> > Next I did r.to.vect with the parameter "feature=area". This indeed ****
>
> > created a polygon vector map:****
>
> > r.to.vect in=nass out=nass feature=area # In the GUI, File->Map type ***
> *
>
> > conversions->Raster to vector****
>
> >** **
>
> > However you need to be aware that the raster will be come many tens of *
> ***
>
> > thousands of small polygons. I downloaded a small section of MA and it *
> ***
>
> > was about 1000 columns X 500 rows. A 500,000 cell raster is not large.**
> **
>
> > But, converted to a vector this became 77,000 little polygons.****
>
> >** **
>
> > So the procedure works. The question is: Is that what you want? What's *
> ***
>
> > your next step?****
>
> >** **
>
> >** **
>
> > Thanks,****
>
> >                  Pedro****
>
> >** **
>
> >** **
>
> > PS - I'm using the GUI****
>
> >** **
>
> >** **
>
> >** **
>
> > This mail was received via Mail-SeCure System.****
>
> >** **
>
> >** **
>
> >** **
>
> > _______________________________________________****
>
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>
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> >****
>
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>
> >   ****
>
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> >   ****
>
> >   ****
>
> >** **
>
> >** **
>
> >** **
>
> > This mail was received via Mail-SeCure System.****
>
> ** **
>
> ** **
>
> --****
>
> Micha Silver****
>
> GIS Consultant, Arava Development Co.****
>
> http://www.surfaces.co.il****
>
>
> This mail was received via Mail-SeCure System.
>
>
>
> --
> Micha Silver
> GIS Consultant, Arava Development Co.http://www.surfaces.co.il
>
>
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