[GRASS-user] Help needed with interactive selection of vectors

[Thomas.Adams at noaa.gov]

Maris,

Sorry for not being clear. Basically now the mode of operation is:

(1) launch ArcGIS which has been customized somewhat to do the following (some background coverages appear automatically for reference, as the link shows)…
(2) the user manually digitizes polygonal areas corresponding to the areas of flood risk
(3) the polygons are annotated to show the period over which they are valid
(4) the custom control buttons allow the user to export the map and to have a text file created and have it ftp'ed to another location

Now, all of this is pretty much doable in GRASS, though the GUI is not as refined and some coding changes would be needed (I think) to 'duplicate' this process. I'm trying to avoid this right now for several reasons, including time constraints. What I thought *could* be done, would be to have some reference subbasin boundaries displayed in the GRASS display window along with the other reference vector maps (state political boundaries and our area of responsibility). Allow the user to interactively select the basins at risk and have those areas ONLY display as areas of risk. Then the process would be similar to (1)—(4), except that:

(1) I do not see how polygons can be manually selected and have the option to remove unselected basins/polygons and
(2) I do not see how to manually annotate a polygon in such a way that the polygon(s) are clearly tied to the annotation.

However, this may all be moot because, it seems, a significant number of people want to have the ability to freehand draw the areas of risk, so that the selection process I was suggesting is not of interest.

Thanks you for your interest!

Regards,
Tom

----- Original Message -----
From: Maris Nartiss <maris.gis at gmail.com>
Date: Thursday, November 8, 2007 2:46 pm
Subject: Re: [GRASS-user] Help needed with interactive selection of vectors

> Hi,
> I was not able to fully understand Your needs. Please clarify 
> following aspects:
> 1) How input data looks like;
> 2) What do You mean by "manually select smaller subbasins"?
> 3) And what is "*direct* link"? Uniq ID or model result parser?
> 
> I assume You have following workflow:
> 1) run some closed modeling program, that outputs some (ASCII?) 
> results;2) operator adds some colors to existing shapes based on 
> 1st step output;
> 3) result is uploaded to server.
> If I'm correct, You could create parser for 1st step result file,
> upload parsed results to database (PostGIS with basins or dbf for
> joining with GRASS vectors) and generate image with areas colored by
> attribute in GRASS/MapServer/GMT/et.al.
> 
> Sorry, if I was thinking in other direction,
> Maris.
> 
> 
> 2007/11/8, Thomas Adams <Thomas.Adams at noaa.gov>:
> > List:
> >
> > I work for the US National Weather Service at the Ohio River 
> Forecast> Center. We generate, on a daily basis, a graphic that 
> looks like this:
> > http://www.erh.noaa.gov/er/ohrfc/fop.html
> >
> > The linked graphic would be pretty trivial to create in GRASS using
> > ps.map. However, during times where there is a reasonable risk for
> > significant flooding, the map must be altered to designate the 
> smaller> subbasins (or areas) that are at risk and to annotate the 
> period over
> > which the threat exists. I'm sorry I can not link an example to 
> show,> since there is no current flooding in the US or risk thereof.
> >
> > Currently, the process is carried out interactively using ArcGIS. 
> I am
> > trying to offer up an open source alternative with GRASS. I am 
> sure a
> > more sensible, non-interactive way of generating the map explicitly
> > through a modeling approach would be best (and we do, of course, 
> base> designating the basins at risk on hydrologic modeling), but 
> there is no
> > *direct* link. Currently human interaction is used and some will 
> insist> on this.
> >
> > So, I am left wondering how to best approach this is GRASS, 
> namely, either:
> >
> > (1) have the ability to manually select smaller subbasins and 
> group them
> > together to designate the area at risk, or
> >
> > (2) hand draw/digitize the area
> >
> > Any suggestions are appreciated!
> >
> > Regards,
> > Tom
> >
> > --
> > Thomas E Adams
> > National Weather Service
> > Ohio River Forecast Center
> > 1901 South State Route 134
> > Wilmington, OH 45177
> >
> > EMAIL:	thomas.adams at noaa.gov
> >
> > VOICE:	937-383-0528
> > FAX:	937-383-0033
> >
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> >
>