[GRASS-user] Conversion from point data to raster in GRASS
Micha Silver
micha at arava.co.il
Thu Dec 18 12:50:58 PST 2014
I see below that your vector has 10,182 points. This raster has
62,264,281 raster cells. So in the raster you have about 6000 cells with
no value (0) for each 1 with some value. I would guess that if you zoom
in very close to some points in the original vector, you will see that
those raster cells have a value.
And again, you most likely should consider some interpolation method.
On 12/18/2014 10:35 PM, BABITHA REDDY wrote:
> Hi,
> The following output i got, for vector converted to raster and for
> that raster i used r.info <http://r.info>
>
> r.info <http://r.info> -g -e map=vtr at battu
> north=5373915
> south=5135385
> east=642315
> west=407385
> nsres=30
> ewres=30
> rows=7951
> cols=7831
> cells=62264281
> datatype=DCELL
> title="Categories (vtr)"
> units="none"
> vertical_datum="none"
> source1="Vector Map:
> RGP_Before_2014_Wagner_s_80_E_of_Hwy_80_E_of_HWY_20_2013_Harvesting_Corn_Harvest_Corn at battu"
> source2="Original scale from vector map: 1:1"
> description="generated by v.to.rast"
> timestamp="none"
>
> On Thu, Dec 18, 2014 at 1:29 PM, Micha Silver <micha at arava.co.il
> <mailto:micha at arava.co.il>> wrote:
>
> The important information is the region settings. Please post the
> output of g.region -p.
> Also r.info <http://r.info> on the resulting raster will help.
>
> Also note, as Tom mentioned, that you probably want to
> *interpolate* a continuous raster from the point values.
> Converting a point vector directly to a raster with v.to.rast will
> give you individual raster pixels with some value, and all the
> rest of the raster pixels with zero (or null).
>
>
> On 12/18/2014 09:10 PM, BABITHA REDDY wrote:
>> Hi,
>> I have to convert the vector(point) data into raster, I imported
>> point data into the GRASS and then used v.to.rast command to
>> convert vector to raster map, but the same problem: nothing is
>> displayed on the display, and query data is giving a value of
>> zero in the map display.
>> If it is a problem with projection and region, please help me to
>> resolve this.
>> the point data's metadata is :
>> Name: RGP_Before_2014_Wagner_s_80_E_of_Hwy_80_E_of_HWY_20_2013_ |
>> | Mapset: battu |
>> | Location: RedRiverValley
>> |
>> | Database: /home/shared/research/GRASSDATA |
>> | Title: |
>> | Map scale: 1:1 |
>> | Name of creator: battu |
>> | Organization: |
>> | Source date: Mon Dec 15 16:18:26 2014
>> |
>> | Timestamp (first layer): none |
>> |----------------------------------------------------------------------------|
>> | Map format: native |
>> |----------------------------------------------------------------------------|
>> | Type of map: vector (level: 2)
>> |
>> | |
>> | Number of points: 10182 Number of centroids: 0
>> |
>> | Number of lines: 0 Number of boundaries: 0 |
>> | Number of areas: 0 Number of islands: 0 |
>> | |
>> | Map is 3D: No |
>> | Number of dblinks: 1 |
>> | |
>> | Projection: UTM (zone 14) |
>> | |
>> | N: 46.98666723 S: 46.97957943
>> |
>> | E: -98.65789266 W: -98.66294363
>> |
>> | |
>> | Digitization threshold: 0 |
>> | Comment: |
>> |
>> and
>> g.proj -p gives me the following:
>> -PROJ_INFO-------------------------------------------------
>> name : Universal Transverse Mercator
>> proj : utm
>> datum : wgs84
>> ellps : wgs84
>> zone : 14
>> no_defs : defined
>> -PROJ_UNITS------------------------------------------------
>> unit : metre
>> units : metres
>> meters : 1
>>
>>
>> Could please anyone help me solve this issue. I need to generate
>> raster maps from given vector(point) data.
>>
>> Thanks
>>
>> On Tue, Dec 9, 2014 at 2:09 PM, Thomas Adams <tea3rd at gmail.com
>> <mailto:tea3rd at gmail.com>> wrote:
>>
>> Babitha,
>>
>> How did you do your vector point to raster interpolation;
>> v.surf.bspline; v.surf.idw; v.krige,…? Did you use d.rast to
>> display the raster map; do you have a MASK set; is your GRASS
>> Region set correctly?
>>
>> Knowing your steps in more detail would be helpful…
>>
>> Tom
>>
>> On Tue, Dec 9, 2014 at 12:53 PM, BABITHA REDDY
>> <reddybabitha at gmail.com <mailto:reddybabitha at gmail.com>> wrote:
>>
>> Hi All,
>>
>> After converting a shape file(point) into raster using
>> GRASS7, it is not displaying the converted raster map.
>> When i query the raster map it is displaying the value as
>> 0, even though there are values.
>>
>> Please help how to solve this problem
>>
>> Thanks
>>
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