[GRASS-user] v.what.vect confusion

[Tyler Smith]

Thanks, Micha.

I figured it out. I had incorrectly connected the database table to the map. The table had multiple key values for each polygon.

The dataset is the Harmonized World Soils Database. I've updated the wiki with correct instructions. I think they're correct, at least.

 http://grasswiki.osgeo.org/wiki/Global_datasets#Harmonized_World_Soil_Database_.28HWSD_Database.29

Best,

Tyler

On March 17, 2014 3:08:37 PM EDT, Micha Silver <micha at arava.co.il> wrote:
>After reading your first post, I tried on a small contrived sample of
>polygons and points. I moved the polygon centroids to "un-natural"
>positions, to try to get the wrong values uploaded to the points attrib
>table. The bottom line was that v.what.vect seemed to work fine.  
>Can you share a sample of your data?
>
>
>On 03/17/2014 06:42 PM, Tyler Smith wrote:
>
>Hi again, I'm still struggling with how to add the attribute values
>from a polygon map to the table for a point map. I've tried
>v.what.vect, as documented in my previous message. Any suggestions
>would be appreciated! Thanks, Tyler On March 14, 2014 2:29:49 PM EDT,
>Tyler Smith <tyler at plantarum.ca> wrote: 
>
>Hello, I have a vector point map, amelanchier, and a vector polygon
>map, hwSoil. I tried to extract data from hwSoil for each point in
>amelanchier as follows: v.db.addcol map=amelanchier columns="T_GRAVEL
>double precision" v.what.vect vector=amelanchier qvector=hwSoil
>qcolumn=T_GRAVEL \ column=T_GRAVEL I've repeated this process for a few
>dozen columns. However, I'm not getting the right values. If I
>investigate a single point using d.what.vect, notice that the values
>for T_GRAVEL in amelanchier is not the same as that in hwSoil. I've
>included some of the other columns that also show small discrepancies.
>d.what.vect -t 82:13:46.5625W(E) 36:23:46.875N(N) hwSoil in PERMANENT
>Area Size - Sq Meters: 10269585820.955 Hectares: 1026958.582 Acres:
>2537669.922 Sq Miles: 3965.1093 Layer: 1 category: 4608 driver: sqlite
>database: /home/tws/grassdata/hwSoilsDB/PERMANENT/sqlite.db table:
>hwsdData key column: MU_GLOBAL ADD_PROP : 0 T_GRAVEL : 10 T_SAND : 49
>T_SILT : 27 T_CLAY : 24 T_USDA_TEX_CLASS : 10 T_REF_BULK_DENSITY : 1.4
>T_BULK_DENSITY : 1.4 amelanchier in PERMANENT Point Layer: 1 category:
>668 driver: sqlite database:
>/home/tws/grassdata/hwSoilsDB/PERMANENT/sqlite.db table: amelanchier
>key column: cat cat : 668 accession : 10-217 species : ARB country :
>USA state : TN y : 36.3966 x : -82.22792 ADD_PROP : 0 T_GRAVEL : 11
>T_SAND : 44 T_SILT : 33 T_CLAY : 23 T_USDA_TEX_CLASS : 9
>T_REF_BULK_DENSITY : 1.39 T_BULK_DENSITY : 1.35 What have I done wrong
>here? Is v.what.vect doing some kind of interpolation? I've attached a
>small section of my map, so you can see that the individual points are
>placed within large polygons, so I don't think there's a chance that
>I'm clicking in a different polygon than the one the point is in.
>Thanks for your help! Tyler
>------------------------------------------------------------------------
>_______________________________________________ grass-user mailing list
>grass-user at lists.osgeo.org
>http://lists.osgeo.org/mailman/listinfo/grass-user 
>
>_______________________________________________ grass-user mailing list
>grass-user at lists.osgeo.org
>http://lists.osgeo.org/mailman/listinfo/grass-user This mail was
>received via Mail-SeCure System. 
>
>
>
>-- Micha Silver GIS Consultant, Arava Development Co.
>http://www.surfaces.co.il 052-3665918