DESCRIPTION

v.profile prints out distance and attributes of points/lines along a profiling line. Distance is calculated from the first profiling line coordinate pair or from the beginning of vector line.
The buffer (tolerance) parameter sets how far point can be located from a profiling line and still be included in the output data set.
The output map option can be used to visually check which points are profiled. The buffer (tolerance) setting does not affect lines. Lines are sampled at their crossing point with profiling line.

By default Z values are printed if input vector is a 3D map. It can be disabled with the -z flag.
The profiling line can be provided as N,E coordinate pairs or from an input vector map. As a profiling line must be a single line, the user should use the profile_where parameter to select a single line from a profile input map if it contains multiple vector features.

NOTES

Currently the module can profile only points and lines (including 3D ones). Areas and other complex features are not supported. If in future users can provide reasonable examples how area sampling should work and why it is important, area (or any other feature type) sampling can be added.

EXAMPLES

List all geonames along part of road NC-96 (NC Basic dataset). The output will be stored in a file for later usage. We will use comma as delimiter and three numbers after decimal separator for distance. Output file will contain data for all points, that are within 500 m range to profiling line. 
v.profile input=geonames@PERMANENT output=/home/user/NC_96_geonames.csv\
  separator=comma dp=3 buffer=500 profile_map=roadsmajor@PERMANENT profile_where=cat=56

# Now lets see the output:
cat NC_96_geonames.csv
Number,Distance,cat,GEONAMEID,NAME,ASCIINAME,ALTERNATEN,FEATURECLA,FEATURECOD,COUNTRYCOD,CC2,ADMIN1,POPULATION,ELEVATION,GTOPO30,TIMEZONE,MODIFICATI,PPLKEY,SRC_ID,MAINT_ID
1,360.719,26881,4482019,"New Zebulon Elementary School","New Zebulon Elementary School","","S","SCH","US","","NC",0,106,91,"America/Iqaluit","2006-01-15 00:00:00",0,0,0
2,846.806,22026,4476596,"Little River, Township of","Little River, Township of","","A","ADMD","US","","NC",0,0,91,"America/Iqaluit","2006-01-15 00:00:00",0,0,0
3,2027.918,16681,4470608,"Hendricks Pond","Hendricks Pond","","H","RSV","US","","NC",0,0,91,"America/Iqaluit","2006-01-15 00:00:00",0,0,0
4,2027.918,16690,4470622,"Hendricks Dam","Hendricks Dam","","S","DAM","US","","NC",0,0,91,"America/Iqaluit","2006-01-15 00:00:00",0,0,0
5,2999.214,39338,4496159,"Union Chapel","Union Chapel","","","","US","","NC",0,0,96,"America/Iqaluit","2006-01-15 00:00:00",0,0,0
6,3784.992,43034,4500325,"Zebulon Airport","Zebulon Airport","","S","AIRP","US","","NC",0,108,98,"America/Iqaluit","2006-01-15 00:00:00",0,0,0

Create river valley crossection and provide river marker (Spearfish dataset): 

# Take elevation samples
r.profile input=elevation.dem@PERMANENT output=/home/user/elevation.profile \
  profile=600570.27364,4920613.41838,600348.034348,4920840.38617

# Now get distance to place where river marker should be set
v.profile input=streams@PERMANENT output=/home/user/river_profile.csv \
  east_north=600570.27364,4920613.41838,600348.034348,4920840.38617

BUGS

Strings are enclosed in double quotes ", still quotes within string are not escaped.

Output does not contain Vector CAT values. Only way how to get CAT value is from the attribute table.

If sampled feature (point, line) contains multiple attribute entries (has multiple CAT values), only the first one is reported. If this is a limitation in some practical use case, a feature request in GRASS GIS issue tracker should be opened.

SEE ALSO

r.profile
Linear Referencing System

AUTHOR

Maris Nartiss

Last changed: $Date$