Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)
University of Basilicata Campus Macchia Romana
85100 - Potenza Italy
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
I'm sorry but the procedure that I proposed does not produce good results. In fact the ascii file produced by v.strahler has very strange orders, and also many 0 (that does not have sense in strahler order!). I think the problem is generated in finding the outlets and/or confluences.
Waiting for the response of the List (please)..
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)
University of Basilicata Campus Macchia Romana
85100 - Potenza Italy
What were the limitations of the GRASS raster-to-vector conversion tools you encountered? It's not clear to me from Fig. 3, but I would like to understand the problem, and I hope you can explain it in a bit more detail.
I'm sorry but the procedure that I proposed does not produce good results. In fact the ascii file produced by v.strahler has very strange orders, and also many 0 (that does not have sense in strahler order!). I think the problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
Well, I am not sure what I am going to do. I would look at the code,
but I am not adept at C. Also, I don't know if I understand the
algorithm, but I think if the topology were complete then it would
work OK. I think the 0 orders are unconnected streams- danglers.
This makes sense because they are neither a tributary nor a main stem.
The topology is the problem, and I can't figure out how to correct
this.
thanks
Stephen Sefick
On Tue, Jul 21, 2009 at 12:34 PM, Markus
Metz<markus.metz.giswork@googlemail.com> wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good results.
In fact the ascii file produced by v.strahler has very strange orders, and
also many 0 (that does not have sense in strahler order!). I think the
problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is
negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it
together
I found that r.strahler.sh works well to delineate streams and correct
topology, (I use a treshold of 1km^2, it works well but don't ask me why
), but (in my little experience) does not work to order streams, so I must
run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying
to produce a topologically correct stream network. There are many breaks in
the flow accumulation grid and I would like to delineate the streams and
"correct" the topology after r.thin and r.to.vect have been preformed so
that I can then use v.strahler to order the streams. Thanks for any help and
I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about
things that are so little or so large that all they really do for us is puff
us up and make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals. -K. Mullis
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.
What were the limitations of the GRASS raster-to-vector conversion tools you encountered?
that problems are shown on fig 4)
1) streams directions are not correct (are random) because we have no information about its directions in raster file
2) there are problems if streamlines toutch each other like
It's not clear to me from Fig. 3, but I would like to understand the problem, and I hope you can explain it in a bit more detail.
In fact I use script to convert Terrain Analysis System data to Grass topological data. I attached it here (note it is not GRASS script with full error handling). Sorry for polish comment but I have not time to translate it. If you need more information how it works contact me off list.
Jarek
BTW I'm about to finish regular grass modue for calculating Strahler Stream order and Shreeve Stream Magnitude. I hope I publish it for testing in next few days. Any help appreciated.
What were the limitations of the GRASS raster-to-vector conversion tools you encountered?
that problems are shown on fig 4)
1) streams directions are not correct (are random) because we have no information about its directions in raster file
2) there are problems if streamlines toutch each other like
Opps... there is the problem in the paper: fig 3 shoud be fig 4 and fig 4 shoud be 3 sorry ....
Jarek
BTW I'm about to finish regular grass modue for calculating Strahler
Stream order and Shreeve Stream Magnitude. I hope I publish it for
testing in next few days. Any help appreciated.
I just don't know how. Tell me what to do - I am new to grass, and I
am a intermediate in compiling software. Also, I am running mac os x
if that makes a difference, and I can also test on a debian ppc linux
laptop.
thanks
Stephen Sefick
On Tue, Jul 21, 2009 at 2:32 PM, Dylan Beaudette<debeaudette@ucdavis.edu> wrote:
On Tuesday 21 July 2009, Jarek Jasiewicz wrote:
BTW I'm about to finish regular grass modue for calculating Strahler
Stream order and Shreeve Stream Magnitude. I hope I publish it for
testing in next few days. Any help appreciated.
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.
Well, I am not sure what I am going to do. I would look at the code,
but I am not adept at C. Also, I don't know if I understand the
algorithm, but I think if the topology were complete then it would
work OK. I think the 0 orders are unconnected streams- danglers.
Should not happen unless you specified real depressions in r.watershed. How did you extract streams?
This makes sense because they are neither a tributary nor a main stem.
The topology is the problem,
What exactly is wrong with topology? The existence of these dangles?
Markus M
and I can't figure out how to correct
this.
thanks
Stephen Sefick
On Tue, Jul 21, 2009 at 12:34 PM, Markus
Metz<markus.metz.giswork@googlemail.com> wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good results.
In fact the ascii file produced by v.strahler has very strange orders, and
also many 0 (that does not have sense in strahler order!). I think the
problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is
negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it
together
I found that r.strahler.sh works well to delineate streams and correct
topology, (I use a treshold of 1km^2, it works well but don't ask me why
), but (in my little experience) does not work to order streams, so I must
run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying
to produce a topologically correct stream network. There are many breaks in
the flow accumulation grid and I would like to delineate the streams and
"correct" the topology after r.thin and r.to.vect have been preformed so
that I can then use v.strahler to order the streams. Thanks for any help and
I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about
things that are so little or so large that all they really do for us is puff
us up and make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals. -K. Mullis
On Wed, Jul 22, 2009 at 2:01 AM, Markus
Metz<markus.metz.giswork@googlemail.com> wrote:
stephen sefick wrote:
Well, I am not sure what I am going to do. I would look at the code,
but I am not adept at C. Also, I don't know if I understand the
algorithm, but I think if the topology were complete then it would
work OK. I think the 0 orders are unconnected streams- danglers.
Should not happen unless you specified real depressions in r.watershed. How
did you extract streams?
flow accumulation from r.watershed -> multiplied by gridcell area and
multiplied by average runoff for that hydrologic unit code in map
calc-> r.thin -> r.to.vect
This makes sense because they are neither a tributary nor a main stem.
The topology is the problem,
What exactly is wrong with topology? The existence of these dangles?
Maybe there is nothing wrong. On further reflection the area that I
am trying to use this procedure on is very flat and there are
intermittent streams and wetlands (site visit) all over the study
area. These non-connected lines maybe showing intermittentancy?
Markus M
and I can't figure out how to correct
this.
thanks
Stephen Sefick
On Tue, Jul 21, 2009 at 12:34 PM, Markus
Metz<markus.metz.giswork@googlemail.com> wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good
results.
In fact the ascii file produced by v.strahler has very strange orders,
and
also many 0 (that does not have sense in strahler order!). I think the
problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is
negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it
together
I found that r.strahler.sh works well to delineate streams and correct
topology, (I use a treshold of 1km^2, it works well but don't ask me
why
), but (in my little experience) does not work to order streams, so I
must
run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am
trying
to produce a topologically correct stream network. There are many
breaks in
the flow accumulation grid and I would like to delineate the streams
and
"correct" the topology after r.thin and r.to.vect have been preformed
so
that I can then use v.strahler to order the streams. Thanks for any
help and
I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking
about
things that are so little or so large that all they really do for us
is puff
us up and make us feel like gods. We are mammals, and have not
exhausted the
annoying little problems of being mammals. -K. Mullis
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.
Well, I am not sure what I am going to do. I would look at the
code, but I am not adept at C.
none the less, it doesn't hurt to look, depending on how it is written
it might be understandable / tweakable.
MMetz:
> What exactly is wrong with topology? The existence of these dangles?
note the v.strahler help page makes special mention that if you used
r.watershed you should check the topology. Maybe it makes a bitter deal
out of that than is really the case?
S:
Maybe there is nothing wrong. On further reflection the area that
I am trying to use this procedure on is very flat and there are
intermittent streams and wetlands (site visit) all over the
study area. These non-connected lines maybe showing
intermittentancy?
do you see a "ladder effect" in the r.to.vect river network?
(like a braided river with all joins at right angles)
maybe that is the problematic topology the module is concerned about?
What exactly is wrong with topology? The existence of these dangles?
note the v.strahler help page makes special mention that if you used
r.watershed you should check the topology. Maybe it makes a bitter deal
out of that than is really the case?
S:
Maybe there is nothing wrong. On further reflection the area that
I am trying to use this procedure on is very flat and there are
intermittent streams and wetlands (site visit) all over the
study area. These non-connected lines maybe showing
intermittentancy?
do you see a "ladder effect" in the r.to.vect river network?
(like a braided river with all joins at right angles)
maybe that is the problematic topology the module is concerned about?
I can only think of these two possible problems - dangles and ladders. Dangles are caused by the method used to extract streams from a flow accumulation map whereas these ladders are an artefact of r.to.vect.
I'm regularly trying out different threshold values in r.watershed, only to get different streams to be vectorized, flow accumulation and drainage direction are not affected by the threshold option in r.watershed. I have an idea for a new module that would take flow accumulation and theshold as input and would then extract streams from it, both as raster and as vector (topologically clean in the v.strahler sense). This new module would work with both SFD and MFD flow accumulation and with r.terraflow flow accumulation. The problem is that the rough concept exists in my head only and I have no time right now to develop this module. All the code is there in r.watershed, it just needs to be reorganized a bit...
Hi all
Hi Markus,
thanks for your answer. I found that the problem is in the topology of the river network. I think that v.strahler produces many '0' because it finds many little 'circles' in the stream vector. I tried to produce the stream network both with r.watershed -> r.to.vect and with r.strahler.sh -> r.to.vect: the results obtained in both ways are very similar. Is there a way to eliminate these circles, not by hand ?
Thank you for your time
margherita
Markus Metz wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good results. In fact the ascii file produced by v.strahler has very strange orders, and also many 0 (that does not have sense in strahler order!). I think the problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)
University of Basilicata Campus Macchia Romana
85100 - Potenza Italy
BTW I'm about to finish regular grass modue for calculating Strahler
Stream order and Shreeve Stream Magnitude. I hope I publish it for
testing in next few days. Any help appreciated.
I would be happy to help test!
Cheers,
Dylan
+1
cheers
margherita
--
Eng. Margherita Di Leo
Ph.D. Student Methods and Technologies for Environmental Monitoring
Department of Environmental Engineering and Physics (DIFA)
University of Basilicata Campus Macchia Romana
85100 - Potenza Italy
Il giorno mer, 22/07/2009 alle 19.35 -0700, Hamish ha scritto:
stephen wrote:
>> Well, I am not sure what I am going to do. I would look at the
>> code, but I am not adept at C.
none the less, it doesn't hurt to look, depending on how it is written
it might be understandable / tweakable.
MMetz:
> > What exactly is wrong with topology? The existence of these dangles?
note the v.strahler help page makes special mention that if you used
r.watershed you should check the topology. Maybe it makes a bitter deal
out of that than is really the case?
S:
> Maybe there is nothing wrong. On further reflection the area that
> I am trying to use this procedure on is very flat and there are
> intermittent streams and wetlands (site visit) all over the
> study area. These non-connected lines maybe showing
> intermittentancy?
do you see a "ladder effect" in the r.to.vect river network?
(like a braided river with all joins at right angles)
maybe that is the problematic topology the module is concerned about?
Hi all
Hi Markus,
thanks for your answer. I found that the problem is in the topology of the river network. I think that v.strahler produces many '0' because it finds many little 'circles' in the stream vector. I tried to produce the stream network both with r.watershed -> r.to.vect and with r.strahler.sh -> r.to.vect: the results obtained in both ways are very similar. Is there a way to eliminate these circles, not by hand ?
r.strahler.sh tries to if I understand the script right, but there must be side effects: what were parallel streams with a ladder may be merged into one stream.
Maybe a new module to extract both raster and vector stream networks from any flow accumulation map would indeed be useful.
Markus M
Markus Metz wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good results. In fact the ascii file produced by v.strahler has very strange orders, and also many 0 (that does not have sense in strahler order!). I think the problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
Markus I believe that would be invaluable. I will help in anyway that I can.
Stephen Sefick
On Thu, Jul 23, 2009 at 9:25 AM, Markus
Metz<markus.metz.giswork@googlemail.com> wrote:
Margherita Di Leo wrote:
Hi all
Hi Markus,
thanks for your answer. I found that the problem is in the topology of the
river network. I think that v.strahler produces many '0' because it finds
many little 'circles' in the stream vector. I tried to produce the stream
network both with r.watershed -> r.to.vect and with r.strahler.sh ->
r.to.vect: the results obtained in both ways are very similar. Is there a
way to eliminate these circles, not by hand ?
r.strahler.sh tries to if I understand the script right, but there must be
side effects: what were parallel streams with a ladder may be merged into
one stream.
Maybe a new module to extract both raster and vector stream networks from
any flow accumulation map would indeed be useful.
Markus M
Markus Metz wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good
results. In fact the ascii file produced by v.strahler has very strange
orders, and also many 0 (that does not have sense in strahler order!). I
think the problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is
negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it
together
I found that r.strahler.sh works well to delineate streams and correct
topology, (I use a treshold of 1km^2, it works well but don't ask me why
), but (in my little experience) does not work to order streams, so I must
run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am
trying to produce a topologically correct stream network. There are many
breaks in the flow accumulation grid and I would like to delineate the
streams and "correct" the topology after r.thin and r.to.vect have been
preformed so that I can then use v.strahler to order the streams. Thanks for
any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking
about things that are so little or so large that all they really do for us
is puff us up and make us feel like gods. We are mammals, and have not
exhausted the annoying little problems of being mammals. -K. Mullis
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.
Hi all
Hi Markus,
thanks for your answer. I found that the problem is in the topology of the river network. I think that v.strahler produces many '0' because it finds many little 'circles' in the stream vector. I tried to produce the stream network both with r.watershed -> r.to.vect and with r.strahler.sh -> r.to.vect: the results obtained in both ways are very similar. Is there a way to eliminate these circles, not by hand ?
r.strahler.sh tries to if I understand the script right, but there must be side effects: what were parallel streams with a ladder may be merged into one stream.
Maybe a new module to extract both raster and vector stream networks from any flow accumulation map would indeed be useful.
Yes, r.to.vect will almost never give correct directional network. It require, as Marcus pointed different approach. r.flow ma be a good starting point to create new module
Jarek
Markus M
Markus Metz wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good results. In fact the ascii file produced by v.strahler has very strange orders, and also many 0 (that does not have sense in strahler order!). I think the problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is negative, e.g.
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it together
I found that r.strahler.sh works well to delineate streams and correct topology, (I use a treshold of 1km^2, it works well but don't ask me why ), but (in my little experience) does not work to order streams, so I must run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying to produce a topologically correct stream network. There are many breaks in the flow accumulation grid and I would like to delineate the streams and "correct" the topology after r.thin and r.to.vect have been preformed so that I can then use v.strahler to order the streams. Thanks for any help and I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted the annoying little problems of being mammals. -K. Mullis
