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
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