[GRASS-user] Measuring Stream Lengths

Dylan Beaudette dylan.beaudette at gmail.com
Sat Jan 30 18:35:57 EST 2010

Hi Rich,

Where did these data come from? It sounds like they were generated
outside of GRASS. Can you describe the structure of this 'streams'
dataset, and possibly how it was made?

In order for v.to.db to function properly, you are going to need:

1. segments with cat numbers, see v.category
2. an attribute table attached to this vector
3. stream names (?) populated in one of the columns, possibly with
v.digit, or v.what
4. create a new column for the segment lengths
5. populate this column, v.to.db


On Sat, Jan 30, 2010 at 3:26 PM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Fri, 29 Jan 2010, Dylan Beaudette wrote:
>> Check out v.to.db for uploading things like line segment length to the
>> attribute table of your vectorized stream lines.
> Dylan,
>  This module needs to have the column name and attribute already present.
> My data source has nothing in the table other than ID information (based on
> long/lat and name, if available). There may be other ESRI look up tables
> with reach length and other useful data, but I've not converted those from
> .dbf to SQLite.
>  I suppose that I need to digitize on the monitor to get the lengths, but I
> wonder how accurate that would be.
>  Suggestions appreciated.
> Thanks,
> Rich
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