Re: [GRASS-user] Is Watershed image segmentation program in GRASS GIS?
Hi there... I used r.grow to segment dNBR images to map wildfires. See: https://www.researchgate.net/publication/269692754_Semi-automated_mapping_of_burned_areas_in_semi-arid_ecosystems_using_MODIS_time-series_imagery Hope it helps... 2015-11-11 3:47 GMT-03:00 Uttam Kumar: > > > Hi All, > > Is watershed image segmentation program or a similar module available in > GRASS GIS? > > I understand that we have r.watershed, i.segment and r.grow in GRASS GIS. > But I do not know which one best suits my problem. > > The problem is: > > I have two layers of raster data - > 1.) a gradient image (obtained by applying a 3 x 3 sobel filter on a water > index using r.mapcalc), and > 2.) a seed image of 2 classes labelled as "1" and "2" and remaining pixels > as "0". > > I want to use the seed image and the gradient image (which shows direction > of change in intensity) information to perform segmentation using the > watershed algorithm and label all "0" pixels as either 1 or 2. > > r.watershed does not use watershed segmentation algorithm. i.segment is > something close but I am not sure. > > Please suggest. > > Any comment is appreciated. > > Uttam. > > > > ___ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > -- Dr. Leonardo A. Hardtke Laboratorio de Teledetección y S.I.G. Centro Nacional Patagónico (CONICET) Bvd. Brown 2825, 9120 Puerto Madryn, Chubut, Argentina ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Is Watershed image segmentation program in GRASS GIS?
On 11/11/15 07:47, Uttam Kumar wrote: Hi All, Is watershed image segmentation program or a similar module available in GRASS GIS? I understand that we have r.watershed, i.segment and r.grow in GRASS GIS. But I do not know which one best suits my problem. The problem is: I have two layers of raster data - 1.) a gradient image (obtained by applying a 3 x 3 sobel filter on a water index using r.mapcalc), and 2.) a seed image of 2 classes labelled as "1" and "2" and remaining pixels as "0". I want to use the seed image and the gradient image (which shows direction of change in intensity) information to perform segmentation using the watershed algorithm and label all "0" pixels as either 1 or 2. r.watershed does not use watershed segmentation algorithm. i.segment is something close but I am not sure. Please suggest. Any comment is appreciated. Currently GRASS GIS only proposes a region-growing segmentation algorithm in i.segment. However, even though it is not really made for this, and I'm not sure of the exact algorithm used in r.watershed, this module can be used for image segmentation. One caveat are the edges which r.watershed treats in a particular manner, but I'm sure a work-around is possible. Moritz ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user