Re: [GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
Hi,
I used the software some time ago and it worked nicely. And as Johannes
explained, the only data needed is the river network and the basin boundary.
I'll try to translate the algorithm behind the software but I'm a bit
confused by it so I could be doing a worse job then a google translator...
1) If a river segment is connected to the river network at only one point
and the segment does not touch the basin boundary, those are the first
order streams rivers and their flow direction can be defined from the
unconnected end to the connected end
2) If the endpoint of a river segment touches other segments that have
their flow directions determined and the flows converge, then:
The flowdirection of the segment goes from the examined endpoint to the
other end;
You can calculate the stream order by looking at the stream orders of
the segments that flow into the analyzed segment.
If the segments that touch an endpoint does not have their flowdirection
determined, then the flowdirection the analyzed endpoint cannot be
determined and that indefinition caries out throuhg the river network (fig2
in the example).
The software does not work if you have loops in your river network.
Here is the link of the manual explaining the algorithm, but it's in
portuguese
http://www.fgel.uerj.br/labgis/hydroflow/Help/helphydroflow.html
Cheers
Daniel
On Tue, Jun 18, 2013 at 11:19 AM, Johannes Radinger <
johannesradin...@gmail.com> wrote:
> 1) Concerning the flow direction / network direction
>
> So far what I can understand from the html-manual, the only two
> input data is the map with the river network and a line or polygon file
> the defines the catchement. The flow direction within the network
> is then defined by the outflow point which is the only line of the river
> that touches or intersects with the catchment border. Unfortunately,
> neither I am a native Brasilian (which makes reading the manual difficult)
> nor
> I am able to read or understand the source code behind the model
>
> 2) Concerning the license
> It is licensed under GNU GPL:
> http://www.fgel.uerj.br/labgis/hydroflow/Help/helphydroflow.html?{D3EB24A2-0B1B-4CA1-B0C6-F05855A23C8D}.htm
>
> @Madi: No unfortunately I haven't tried HydroFlow yet. I first have to
> figure out how to compile it using qmake on my ubuntu machine. Concerning
> v.strahler: AFAIK also this module needs a DEM to identify flow direction,
> which is often not available when you have only the river vector. And of
> course HydroFlow also provides other measures of stream order beside
> Strahler...
>
> I hopefully get the tool installed quite soon. I will then report how well
> it is working.
>
> /Johannes
>
>
> On Tue, Jun 18, 2013 at 3:08 PM, Markus Metz <
> markus.metz.gisw...@gmail.com> wrote:
>
>> On Tue, Jun 18, 2013 at 1:52 PM, Johannes Radinger
>> wrote:
>> > Hi,
>> >
>> > I found following interesting Brasilian program called HydroFlow:
>> > http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html
>> >
>> > This tools calculates the Stream order (e.g. Strahler, Shreve)
>> > based on a shapefile input of the river network and a shapefile that
>> defines
>> > the border (catchment?). If I am informed correctly such a tool that
>> does
>> > not require any form of a DEM (or accumulation map etc.) is not
>> existing for
>> > GRASS yet.
>>
>> One bit of requirement information must be provided in addition to the
>> shapefile: the outlet of a river network. If the lines of the
>> shapefile follow drainage dirction, this is possible, because then per
>> network only one line will go towards an end point. You could look at
>> the description or source code if possible to find out how HydroFlow
>> identifies the outlet of a river network.
>>
>> Markus M
>>
>>
>> >
>> > There are just two questions that appeared to me:
>> >
>> > 1) Has anyone installed and tried the programm already in Ubuntu/Linux?
>> >
>> > 2) The tool is licensed as open source. So, could such a algorithm also
>> be
>> > implemented as
>> > a add-on to GRASS? I am not sure but I can imagine that this might be of
>> > interest also to
>> > other GRASS users!?
>> >
>> > /johannes
>> >
>> > ___
>> > grass-user mailing list
>> > grass-user@lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/grass-user
>> >
>>
>
>
> ___
> grass-user mailing list
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> http://lists.osgeo.org/mailman/listinfo/grass-user
>
>
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[GRASS-user] CALL FOR PAPERS - Geological and Geomorphological Applications of Digital Terrain Analysis (GSA Annual Meeting 2013)
CALL FOR PAPERS (Apologies for cross-posting) Geological Society of America Annual Meeting Denver, Colorado, 27-30 October 2013 Abstracts submission deadline: 6 August http://www.geosociety.org/meetings/2013/sessions/topical.asp T91. Geological and Geomorphological Applications of Digital Terrain Analysis Carlos Henrique Grohmann, Christopher J. Crosby Monitoring and quantification of rates of geomorphic processes requires repeated acquisition of accurate, high-resolution topographic information. The rapid growth in the availability of Digital Elevation Models (DEMs) such as the Shuttle Radar Topography Mission, TerraSAR-X Satellite Mission, ICESat and CryoSat missions, photogrammetric-derived DEMs from orbital imagery (ALOS, ASTER, SPOT) or from unmanned aerial vehicles (UAVs) and laser altimetry/scanning (LiDAR), provide a way to look at the topography of our planet with an unprecedented detail, often allowing the recognition of previously unknown features and the establishment of their spatial relationships. Digital Terrain Analysis (DTA) provides the framework for terrain quantification, segmentation and classification, aiming at the recognition and simulation of geomorphic processes. Advances in DTA have had impacts in areas such as hazard andrisk assessment, geomorphologic process evaluation, morphotectonic interpretation, and geophysical data processing. This session will provide an excellent opportunity to present and discuss recent advances in methods,algorithms, and applications of DTA to geology and geomorphology. The 2013 GSA annual meeting takes place one week after the Geomorphometry2013 (http://geomorphometry.org/2013) international conference in Nanjing, China; we expect this session at GSA to build on the momentum from the China conference and to extend and expand DTA discussions and networking between scientists in this rapid-growing field. http://community.geosociety.org/2013AnnualMeeting/Home best Carlos Grohmann -- Prof. Carlos Henrique Grohmann Institute of Geosciences - Univ. of São Paulo, Brazil - Digital Terrain Analysis | GIS | Remote Sensing - http://carlosgrohmann.com http://orcid.org/-0001-5073-5572 Can’t stop the signal. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] [LAStools] Computing for the Density
Hello Charm, great question. Since you are expecting around 2 pulses per square meter and since you are using a step of 5 which equals 5m by 5m = 25 m^2 and since you are using the last only (or first only) retirn filter to count only one return per pulse you should expect to get values around 50 in the grid cells. You will get - possibly much - smaller values whenever the strip does not fully cover the grid cell. It is possible that just one pulse hits one corner of a grid cell. You will get - possibly much - larger values when the sampling on the ground gets condensed (but also streched out) because of strong pitch variations of a small aircraft in turbulences. But the more "systematic" larger values come from hardware that use a zig-zag scanner to scan. As the oszillating mirror slows down to change direction at the scan line edges you tend to get much much denser sampling there ... somewhat unrepresentative for the average sampling so it is important for zig zag scanners not to count the density of points along the edges when computing averages. One way of "not" counting them is to use a filter on the scan angle. For example lasinfo -i sample.laz ^ -compute_density ^ -drop_abs_scan_angle_above 18 or lasgrid -i sample.laz ^ -density -step 5 ^ -drop_scan_angle -20 20 ^ -o density_25sqrmtr.asc could do the trick. Another issue ... if you density ranges up to 255 then higher values may be cut off and you should use '-density_16bit' instead of '-density' and use wider counters (16 bit instead of 8 bit). Regards, Martin On Jun 17, 2013, at 3:39, Charmaine Cruz wrote: > Hi Martin and everyone, > > I would like to ask a question about lastools. > My task is to compute for the density of LiDAR points for every flight. > From my previous report, I used lasgrid to compute for the actual values of > density (step is 5) and the output is number of points per 25 sqm, and it > ranges from 1-255. It seems that I get higher value of density than expected. > > What is the importance of considering the value of scan angle in computing > for the density? > > Thank you very much.. :) > > -- > Engr. Charmaine A. Cruz > Research Associate > Disaster Risk and Exposure Assessment for Mitigation (DREAM) Program > National Engineering Center > Alfredo Junio Hall > University of the Philippines Campus > Diliman, Quezon City 1110 > +639159383637 > > > -- > Download LAStools at > http://lastools.org > http://rapidlasso.com > Be social with LAStools at > http://facebook.com/LAStools > http://twitter.com/LAStools > http://linkedin.com/groups/LAStools-4408378 > Manage your settings at > http://groups.google.com/group/lastools/subscribe > > -- Download LAStools at http://lastools.org http://rapidlasso.com Be social with LAStools at http://facebook.com/LAStools http://twitter.com/LAStools http://linkedin.com/groups/LAStools-4408378 Manage your settings at http://groups.google.com/group/lastools/subscribe ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Google Groups Invitation: LAStools - efficient tools for LiDAR processing
this discussion group on LiDAR processing with LAStools tends to have plenty of interesting topics About this group: LAStools are a collection of highly-efficient, batch scriptable, multi-core command line tools (with GUI and ArcGIS toolbox) for processing LiDAR that is built upon LASlib (with LASzip). We announce new releases and discuss whatever of interest to those processing billions of LiDAR points. Accept this invitation: http://groups.google.com/group/lastools/sub?s=IIzkixQAAABgeCJzPKlh5pok34Hj0DmmGkaXaBZ9l455j8Ixb4EWdA&hl=en Visit this group: http://groups.google.com/group/lastools?hl=en You can unsubscribe from this group using the following URL: http://groups.google.com/group/lastools/unsub?u=IIzkixQAAABgeCJzPKlh5pok34Hj0DmmGkaXaBZ9l455j8Ixb4EWdA&hl=en If you feel that this message is abuse, please inform the Google Groups staff by using the URL below. http://groups.google.com/groups/abuse?direct=YQAAAIb6S2-c4EbiTJsAAADPQv5WpYF4_V1sH6WAqxO-tgcc8gU&hl=en ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
1) Concerning the flow direction / network direction
So far what I can understand from the html-manual, the only two
input data is the map with the river network and a line or polygon file
the defines the catchement. The flow direction within the network
is then defined by the outflow point which is the only line of the river
that touches or intersects with the catchment border. Unfortunately,
neither I am a native Brasilian (which makes reading the manual difficult)
nor
I am able to read or understand the source code behind the model
2) Concerning the license
It is licensed under GNU GPL:
http://www.fgel.uerj.br/labgis/hydroflow/Help/helphydroflow.html?{D3EB24A2-0B1B-4CA1-B0C6-F05855A23C8D}.htm
@Madi: No unfortunately I haven't tried HydroFlow yet. I first have to
figure out how to compile it using qmake on my ubuntu machine. Concerning
v.strahler: AFAIK also this module needs a DEM to identify flow direction,
which is often not available when you have only the river vector. And of
course HydroFlow also provides other measures of stream order beside
Strahler...
I hopefully get the tool installed quite soon. I will then report how well
it is working.
/Johannes
On Tue, Jun 18, 2013 at 3:08 PM, Markus Metz
wrote:
> On Tue, Jun 18, 2013 at 1:52 PM, Johannes Radinger
> wrote:
> > Hi,
> >
> > I found following interesting Brasilian program called HydroFlow:
> > http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html
> >
> > This tools calculates the Stream order (e.g. Strahler, Shreve)
> > based on a shapefile input of the river network and a shapefile that
> defines
> > the border (catchment?). If I am informed correctly such a tool that does
> > not require any form of a DEM (or accumulation map etc.) is not existing
> for
> > GRASS yet.
>
> One bit of requirement information must be provided in addition to the
> shapefile: the outlet of a river network. If the lines of the
> shapefile follow drainage dirction, this is possible, because then per
> network only one line will go towards an end point. You could look at
> the description or source code if possible to find out how HydroFlow
> identifies the outlet of a river network.
>
> Markus M
>
>
> >
> > There are just two questions that appeared to me:
> >
> > 1) Has anyone installed and tried the programm already in Ubuntu/Linux?
> >
> > 2) The tool is licensed as open source. So, could such a algorithm also
> be
> > implemented as
> > a add-on to GRASS? I am not sure but I can imagine that this might be of
> > interest also to
> > other GRASS users!?
> >
> > /johannes
> >
> > ___
> > grass-user mailing list
> > grass-user@lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/grass-user
> >
>
___
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Re: [GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
On Tue, Jun 18, 2013 at 1:52 PM, Johannes Radinger wrote: > Hi, > > I found following interesting Brasilian program called HydroFlow: > http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html > > This tools calculates the Stream order (e.g. Strahler, Shreve) > based on a shapefile input of the river network and a shapefile that defines > the border (catchment?). If I am informed correctly such a tool that does > not require any form of a DEM (or accumulation map etc.) is not existing for > GRASS yet. One bit of requirement information must be provided in addition to the shapefile: the outlet of a river network. If the lines of the shapefile follow drainage dirction, this is possible, because then per network only one line will go towards an end point. You could look at the description or source code if possible to find out how HydroFlow identifies the outlet of a river network. Markus M > > There are just two questions that appeared to me: > > 1) Has anyone installed and tried the programm already in Ubuntu/Linux? > > 2) The tool is licensed as open source. So, could such a algorithm also be > implemented as > a add-on to GRASS? I am not sure but I can imagine that this might be of > interest also to > other GRASS users!? > > /johannes > > ___ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
Hi Johannes! I tried that program like a year or more ago .. It worked well once you know howto do it .. It delivers it's one shapelib with it and can only do changes on shapefiles .. So it must be probably changed to a neutral dataset provider .. I was about to adapt it for QGIS but did not have any time until now to do so.. Probably in the future when I have more time to learn more cpp skills .. But as I said the program itself works well .. But is it really open source? I am not quite sure if there weren't any issues with the license that kept me away from porting it .. kind regards Werner On Tue, Jun 18, 2013 at 1:52 PM, Johannes Radinger < johannesradin...@gmail.com> wrote: > Hi, > > I found following interesting Brasilian program called HydroFlow: > http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html > > This tools calculates the Stream order (e.g. Strahler, Shreve) > based on a shapefile input of the river network and a shapefile that > defines > the border (catchment?). If I am informed correctly such a tool that does > not require any form of a DEM (or accumulation map etc.) is not existing > for > GRASS yet. > > There are just two questions that appeared to me: > > 1) Has anyone installed and tried the programm already in Ubuntu/Linux? > > 2) The tool is licensed as open source. So, could such a algorithm also be > implemented as > a add-on to GRASS? I am not sure but I can imagine that this might be of > interest also to > other GRASS users!? > > /johannes > > ___ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > > ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
On Tue, Jun 18, 2013 at 1:58 PM, Margherita Di Leo wrote: > Did you try it yourself? How's the outcome? > > I mean, did you try the HydroFlow software -- Best regards, Margherita DI LEO Postdoctoral Researcher European Commission - DG JRC Institute for Environment and Sustainability (IES) Via Fermi, 2749 I-21027 Ispra (VA) - Italy - TP 261 Tel. +39 0332 78 3600 margherita.di-...@jrc.ec.europa.eu Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
Hi Johannes, On Tue, Jun 18, 2013 at 1:52 PM, Johannes Radinger < johannesradin...@gmail.com> wrote: > Hi, > > I found following interesting Brasilian program called HydroFlow: > http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html > > This tools calculates the Stream order (e.g. Strahler, Shreve) > based on a shapefile input of the river network and a shapefile that > defines > the border (catchment?). If I am informed correctly such a tool that does > not require any form of a DEM (or accumulation map etc.) is not existing > for > GRASS yet. > there is v.strahler http://grasswiki.osgeo.org/wiki/AddOns/GRASS_6#v.strahler that calculates the Strahler order. I'm not aware of its status though, I remember some issues reported in ML but I didn't keep myself updated. > > There are just two questions that appeared to me: > > 1) Has anyone installed and tried the programm already in Ubuntu/Linux? > > 2) The tool is licensed as open source. So, could such a algorithm also be > implemented as > a add-on to GRASS? I am not sure but I can imagine that this might be of > interest also to > other GRASS users!? > Nice idea! Did you try it yourself? How's the outcome? cheers, madi > > > /johannes > > ___ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > > -- Best regards, Margherita DI LEO Postdoctoral Researcher European Commission - DG JRC Institute for Environment and Sustainability (IES) Via Fermi, 2749 I-21027 Ispra (VA) - Italy - TP 261 Tel. +39 0332 78 3600 margherita.di-...@jrc.ec.europa.eu Disclaimer: The views expressed are purely those of the writer and may not in any circumstance be regarded as stating an official position of the European Commission. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] HydroFlow: Stream order soleley based on shape files/vectors
Hi, I found following interesting Brasilian program called HydroFlow: http://www.fgel.uerj.br/labgis/hydroflow/en/downloads_ingles.html This tools calculates the Stream order (e.g. Strahler, Shreve) based on a shapefile input of the river network and a shapefile that defines the border (catchment?). If I am informed correctly such a tool that does not require any form of a DEM (or accumulation map etc.) is not existing for GRASS yet. There are just two questions that appeared to me: 1) Has anyone installed and tried the programm already in Ubuntu/Linux? 2) The tool is licensed as open source. So, could such a algorithm also be implemented as a add-on to GRASS? I am not sure but I can imagine that this might be of interest also to other GRASS users!? /johannes ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] new north arrow symbols
Hellos, six new north arrow symbols to try out: http://grasswiki.osgeo.org/wiki/IconSymbols#New I'm not toally happy with n_arrow5: I didn't figure a way to make a hole in the filled-arc, so the "N" is hardcoded to filled-with-white. (so you can't set inverse colors on that one. the big triangle in it is transparent btw) hmm, maybe I could leave a sliver to the outside space then mask over it with a polygon with no border color and background color matching the main body? ... TBC Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] r.surf.nnbathy with GRASS 7?
Ivan: > I use it in Grass 7. it works. Adam wrote: >>> Is r.surf.nnbathy compatible with GRASS 7.0? Hamish: >>I don't think there is a newer version, but there's >>a good chance that the GRASS 6 one still works. Give >>it a try and let us know! Adam: > Thanks. It is working. Hamish: >> In general cloned code is to be avoided, and svn >> supports symlinking, so a possible solution for >> known working addons (scripts) is to symlink in >> the parent directory. Hopefully the build system >> is not too grumpy about mixed python and shell >> scripts. If it is we should come up with a solution >> to fix that. I've just added a new r.surf.nnbathy dir in the grass7/raster addons, with symlinks back to the grass6 dir. I had to do each file individually instead of jus the dir since description.html needs to be renamed to [g.module].html. Svn stores it as a "link" file internally, and I believe a checkout on Windows will make a full copy of the files since there are no symlinks there. if it works it will be a nice temporary solution to avoid the extra maintenance overhead and divergence. Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
