<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Janet,<div><br></div><div>if you choose "use=attr" then the value of the</div><div>attribute you set with "column=xxx" is used</div><div>as the value for the raster pixel. You can check</div><div>your attribute table to find out which attribute values</div><div>are assign to each road section.</div><div><br></div><div>If you just want a "fix value" for each raster pixel of the road,</div><div> you have to set "use=val" and then</div><div>provide a value you want (value=xxx).</div><div><br></div><div>So it depends what you're looking for. Which values</div><div>do you want to be assigned to you road-pixel in the raster format?</div><div><br></div><div>best regards,</div><div>Johannes</div><div><br></div><div><div><div>Am 14.03.2012 um 07:29 schrieb Janet Choate:</div><br class="Apple-interchange-newline"><blockquote type="cite">Hi users,<div>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.</div><div>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:</div>
<div><div><br></div><div>v.to.rast input=roads output=roads</div><div>ERROR: Column parameter missing (or use value parameter)</div></div><div><br></div><div>but if i run as:</div><div>v.to.rast input=roads output=roads5 use=attr column=ROADNR<br>
</div><div>(or column=CODE, etc..)</div><div><br></div><div>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 (<em style="background-color:rgb(255,255,255);font-family:Times;font-size:medium">attr,cat,val,z,dir)</em></div>
<div><em style="background-color:rgb(255,255,255);font-family:Times;font-size:medium"><br></em></div><div><span style="background-color:rgb(255,255,255);font-family:Times;font-size:medium">running db.describe on the road vector, i get the following info:</span></div>
<div><span style="background-color:rgb(255,255,255);font-family:Times;font-size:medium"><div>db.describe -c table=roads</div><div>ncols: 14</div><div>nrows: 383</div><div>Column 1: cat:INTEGER:11</div><div>Column 2: UserId:INTEGER:11</div>
<div>Column 3: FNODE_:INTEGER:11</div><div>Column 4: TNODE_:INTEGER:11</div><div>Column 5: LPOLY_:INTEGER:11</div><div>Column 6: RPOLY_:INTEGER:11</div><div>Column 7: LENGTH:DOUBLE PRECISION:20</div><div>Column 8: GI00701_:INTEGER:11</div>
<div>Column 9: GI00701_ID:INTEGER:11</div><div>Column 10: YEAR:INTEGER:11</div><div>Column 11: ROADDEC:INTEGER:11</div><div>Column 12: CODE:INTEGER:11</div><div>Column 13: STAT:CHARACTER:1</div><div>Column 14: ROADNR:INTEGER:11</div>
<div><br></div><div>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.</div><div>thank you, </div><div>Janet</div>
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