5,038 reputation
513
bio website surfaces.co.il
location Israel
age
visits member for 3 years
seen 4 hours ago

I work at the Arava Drainage Authority and Regional Council in southern Israel, doing hydrological analysis and general mapping. Involved with open source software since 1996, and FOSS GIS since 2006. I've also organized a few short GIS training seminars based on open source software.


16h
answered Proof low deviations in DEM compared to point dataset
19h
answered Is there Data Loader for QGIS or Spatialite?
20h
comment Proof low deviations in DEM compared to point dataset
I thnk that IDW is not the best interpolation method for creating a DEM from point elevations. How dense is your regular point dataset? and what final resolution do you want? With that information, you probably will want to choose a spline or kriging method, probably using GRASS, saga, or similar.
Mar
24
comment What is the “best” way to automate the GIS slope and aspect algorithm?
I would add that GRASS has a set of modules for working with Lidar clouds. What might be of interest is the v.lidar.edgedetection module
Mar
17
awarded  Nice Answer
Mar
17
answered Polygon centroid coordinates update error
Mar
12
answered QGIS – Raster Calculator: Using flat (no data) areas of an aspect-raster in the raster calculator
Mar
11
awarded  Yearling
Mar
5
answered How to visualize a point cloud in 3D with GRASS?
Feb
26
revised How to do a looping for importing and interpolating a lot of LIDAR files?
Added some hints to run the loop in python
Feb
25
comment Calculate River Runoff Volume (Q) with GRASS
Calculating runoff from precipitation over a catchment basin is a complicated task. There are many additional factors beyond the drainage area and total precipitation: infiltration, slope, evaporation, manning coefficient, etc. You probably should be looking at models such as HEC-HMS.
Feb
24
comment What is the background processing of rainfall thresholding?
The threshold value in watershed delineation depends of your needs, size of the region and the resolution of the DEM that your analysis is based on. The value represents the number of raster cells that would make up a minimum catchment area. So if, for example, you want to delineate catchments of 10 sq km or more, then you need to calculate how many raster cells would total to 10 sq km.
Feb
22
answered How to do a looping for importing and interpolating a lot of LIDAR files?
Feb
17
answered Discrete Waterpoints with Grass
Feb
16
comment Discrete Waterpoints with Grass
You probably want to have a look at the set of modules: r.stream.* . Details are here: grasswiki.osgeo.org/wiki/R.stream.*_modules. You can use the r.stream.stats module to get slopes of each stream reach, and the r.stream.basins to get catchments for points along the streams.
Feb
13
comment Adding Nodes to Linestrings at Overlapping Points with Polygon Layer in Spatialite
Very nice. I tried to find a simple answer to your original question, but nothing surfaced. Thanks for posting this.
Feb
11
answered r.in.xyz doesn't work in GRASS
Feb
10
comment r.in.xyz doesn't work in GRASS
I run an automated GRASS script several times a day with exactly the commands that gene suggested. So it most certainly DOES work. Can you report the output of r.in.xyz -s, and also g.region -p ??
Jan
30
awarded  Revival
Jan
21
awarded  Enlightened