Hi users,
i’ve read the help and other posts regarding v.to.rast, but i’m still not piecing it all together and would appreciate some help.
i have a vector map of roads that i want to convert to a raster, so it is lines. v.support - fine, but i can not figure out what i need to do with v.digit (and if v.digit is necessary), don’t know how to use. after running v.support, if i just run v.to.rast as:
v.to.rast input=roads output=roads
ERROR: Column parameter missing (or use value parameter)
but if i run as:
v.to.rast input=roads output=roads5 use=attr column=ROADNR
(or column=CODE, etc…)
then i get a raster. values of the raster differ based on what column i choose. so my question is, how do i choose the column, and how do i know what to set use= to (attr,cat,val,z,dir)
running db.describe on the road vector, i get the following info:
db.describe -c table=roads
ncols: 14
nrows: 383
Column 1: cat:INTEGER:11
Column 2: UserId:INTEGER:11
Column 3: FNODE_:INTEGER:11
Column 4: TNODE_:INTEGER:11
Column 5: LPOLY_:INTEGER:11
Column 6: RPOLY_:INTEGER:11
Column 7: LENGTH:DOUBLE PRECISION:20
Column 8: GI00701_:INTEGER:11
Column 9: GI00701_ID:INTEGER:11
Column 10: YEAR:INTEGER:11
Column 11: ROADDEC:INTEGER:11
Column 12: CODE:INTEGER:11
Column 13: STAT:CHARACTER:1
Column 14: ROADNR:INTEGER:11
if anyone can please advise the process of turning a vector into a raster, i.e. what commands are necessary first and how to apply them, i would really appreciate it.
thank you,
Janet
Hi Janet,
if you choose “use=attr” then the value of the
attribute you set with “column=xxx” is used
as the value for the raster pixel. You can check
your attribute table to find out which attribute values
are assign to each road section.
If you just want a “fix value” for each raster pixel of the road,
you have to set “use=val” and then
provide a value you want (value=xxx).
So it depends what you’re looking for. Which values
do you want to be assigned to you road-pixel in the raster format?
best regards,
Johannes
Am 14.03.2012 um 07:29 schrieb Janet Choate:
Hi users,
i’ve read the help and other posts regarding v.to.rast, but i’m still not piecing it all together and would appreciate some help.
i have a vector map of roads that i want to convert to a raster, so it is lines. v.support - fine, but i can not figure out what i need to do with v.digit (and if v.digit is necessary), don’t know how to use. after running v.support, if i just run v.to.rast as:
v.to.rast input=roads output=roads
ERROR: Column parameter missing (or use value parameter)
but if i run as:
v.to.rast input=roads output=roads5 use=attr column=ROADNR
(or column=CODE, etc…)
then i get a raster. values of the raster differ based on what column i choose. so my question is, how do i choose the column, and how do i know what to set use= to (attr,cat,val,z,dir)
running db.describe on the road vector, i get the following info:
db.describe -c table=roads
ncols: 14
nrows: 383
Column 1: cat:INTEGER:11
Column 2: UserId:INTEGER:11
Column 3: FNODE_:INTEGER:11
Column 4: TNODE_:INTEGER:11
Column 5: LPOLY_:INTEGER:11
Column 6: RPOLY_:INTEGER:11
Column 7: LENGTH:DOUBLE PRECISION:20
Column 8: GI00701_:INTEGER:11
Column 9: GI00701_ID:INTEGER:11
Column 10: YEAR:INTEGER:11
Column 11: ROADDEC:INTEGER:11
Column 12: CODE:INTEGER:11
Column 13: STAT:CHARACTER:1
Column 14: ROADNR:INTEGER:11
if anyone can please advise the process of turning a vector into a raster, i.e. what commands are necessary first and how to apply them, i would really appreciate it.
thank you,
Janet
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Johannes,
thank you very much, that was all i needed. so simple, i appreciate the explanation!
thanx,
Janet
On Wed, Mar 14, 2012 at 1:12 AM, Johannes Radinger <jradinger@gmx.at> wrote:
Hi Janet,
if you choose “use=attr” then the value of the
attribute you set with “column=xxx” is used
as the value for the raster pixel. You can check
your attribute table to find out which attribute values
are assign to each road section.
If you just want a “fix value” for each raster pixel of the road,
you have to set “use=val” and then
provide a value you want (value=xxx).
So it depends what you’re looking for. Which values
do you want to be assigned to you road-pixel in the raster format?
best regards,
Johannes
Am 14.03.2012 um 07:29 schrieb Janet Choate:
Hi users,
i’ve read the help and other posts regarding v.to.rast, but i’m still not piecing it all together and would appreciate some help.
i have a vector map of roads that i want to convert to a raster, so it is lines. v.support - fine, but i can not figure out what i need to do with v.digit (and if v.digit is necessary), don’t know how to use. after running v.support, if i just run v.to.rast as:
v.to.rast input=roads output=roads
ERROR: Column parameter missing (or use value parameter)
but if i run as:
v.to.rast input=roads output=roads5 use=attr column=ROADNR
(or column=CODE, etc…)
then i get a raster. values of the raster differ based on what column i choose. so my question is, how do i choose the column, and how do i know what to set use= to (attr,cat,val,z,dir)
running db.describe on the road vector, i get the following info:
db.describe -c table=roads
ncols: 14
nrows: 383
Column 1: cat:INTEGER:11
Column 2: UserId:INTEGER:11
Column 3: FNODE_:INTEGER:11
Column 4: TNODE_:INTEGER:11
Column 5: LPOLY_:INTEGER:11
Column 6: RPOLY_:INTEGER:11
Column 7: LENGTH:DOUBLE PRECISION:20
Column 8: GI00701_:INTEGER:11
Column 9: GI00701_ID:INTEGER:11
Column 10: YEAR:INTEGER:11
Column 11: ROADDEC:INTEGER:11
Column 12: CODE:INTEGER:11
Column 13: STAT:CHARACTER:1
Column 14: ROADNR:INTEGER:11
if anyone can please advise the process of turning a vector into a raster, i.e. what commands are necessary first and how to apply them, i would really appreciate it.
thank you,
Janet
grass-user mailing list
grass-user@lists.osgeo.org
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