Thank you for your suggestions. It seems I will be having a hard time!!<br><br>@Jarek - The vector has a good topology (I tested the topology using the layer to run a simple nearest path analysis and it worked, so I assume it's ok) I checked the attribute table and it has hundreds of objects and only two have name and type - the main rivers).<br>
<br>If I manage a solution other than manually build a new layer I'll be sure to share it here.<br><br>@ Hamish - Is it possible to test tha tool through QGIS?<br><br>Thank you all<br><br>André<br><br><div class="gmail_quote">
2012/1/30 Jarek Jasiewicz <span dir="ltr"><<a href="mailto:jarek.jasiewicz@gmail.com" target="_blank">jarek.jasiewicz@gmail.com</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div>On 01/30/2012 04:32 PM, Helmut Kudrnovsky wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
André wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I Have a vector layer with all the rivers, and<br>
subsidiaries up to the smallest water lines.<br>
However I need to simplify this layer in order that<br>
it only shows the main rivers and first, second and<br>
third order tributary water lines.<br>
<br>
Any hints on how to achieve this?<br>
</blockquote>
try the v.strahler addon module:<br>
<br>
<a href="http://grass.osgeo.org/wiki/GRASS_AddOns#v.strahler" target="_blank">http://grass.osgeo.org/wiki/<u></u>GRASS_AddOns#v.strahler</a><br>
</blockquote>
or try the very nice r.stream.*-suite<br>
<br>
<a href="http://grass.osgeo.org/wiki/GRASS_AddOns#r.stream.angle" target="_blank">http://grass.osgeo.org/wiki/<u></u>GRASS_AddOns#r.stream.angle</a> and following<br>
<br>
r.stream.angle<br>
r.stream.basins<br>
r.stream.del<br>
r.stream.distance<br>
r.stream.extract<br>
r.stream.order<br>
r.stream.pos<br>
r.stream.stats<br>
<br>
<a href="https://svn.osgeo.org/grass/grass-addons/grass6/raster/r.stream.order/description.html" target="_blank">https://svn.osgeo.org/grass/<u></u>grass-addons/grass6/raster/r.<u></u>stream.order/description.html</a><br>
<br>
strahler<br>
Name of Strahler's stream order output map: see notes for detail.<br>
shreve<br>
Name of Shreve's stream magnitude output map: see notes for detail.<br>
horton<br>
Name of Horton's stream order output map (require accum file): see notes<br>
for detail.<br>
hack<br>
Name of Hack's main streams output map : see notes for detail.<br>
top<br>
Name of topological dimensions streams output map: see notes for detail.<br>
<br>
HTH<br>
Helmut<br>
<br>
-----<br>
best regards<br>
Helmut<br>
--<br>
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</blockquote></div></div>
I do not think that r.stream* is useful here. As I understand you have vector network and you do not need to generate it. The only question is it is topological network, if so Hamish's suggestion to use v.strahler, looks well however this tool is very unstable. If it is not topological network i have no idea how to do that.<br>
<br>
Also check attributes of that verctor. Such databases usually comes from national hydrological surveys and have complete attributes attached to it. So maybe your problem can by solved simply by vector query?<div>
<div><br>
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