I thought that I could use LiDAR data within grass, but the 6.4 r.in.gdal
man page does not include that format. Is this the wrong module for these data?
There are two topographic quadrangle files that cover the project drainage
basin, and the data DVDs cost $200 each. I want to make high resolution DEMs
of the project basin and try to determine flood elevations for different
storm events from those. According to the data source, "All data are format
specific to ESRI GIS format. Data must be viewed using specialty software
capable of viewing .shp, geotif, and ESRI grid formats."
I suppose that r.in.gdal will import the .shp files. I've not worked with
geotif or ESRI grid formats so any experiences of you folks with these
formats and LiDAR data will be much appreciated.
Geotiff is more than supported in the OSGeo world. And ESRI grid's I've
imported (and exported after some trial and error) successfully sometimes,
not worked frequently with such a format though.
Nikos,
I've imported ESRI grid data as the 10m resolution DEMs for the state
here. But, I've not before worked with geotiff files. I'll read the
references you provided and take all the help I can get grom the GRASS-LiDAR
experts. By next Tuesday I need to have some high resolution
terrain/hydrologic models run to estimate flood elevations given channel
size (from the LiDAR DEM) and point rainfall data over a 2 week period.
My 2 drachmas [4] (kept some of the previous greek coins for any case...
:-p),
On Thursday 10 of June 2010 00:14:29 Rich Shepard wrote:
I thought that I could use LiDAR data within grass, but the 6.4
r.in.gdal man page does not include that format. Is this the wrong module
for these data?
There are two topographic quadrangle files that cover the project
drainage basin, and the data DVDs cost $200 each. I want to make high
resolution DEMs of the project basin and try to determine flood elevations
for different storm events from those. According to the data source, "All
data are format specific to ESRI GIS format. Data must be viewed using
specialty software capable of viewing .shp, geotif, and ESRI grid
formats."
I suppose that r.in.gdal will import the .shp files. I've not worked
with geotif or ESRI grid formats so any experiences of you folks with
these formats and LiDAR data will be much appreciated.
I am sending you also off-line some work I've done and includes some notes on
Geotiff's (quite useful for me at the time). Results not include (due to
external forces :-p). Hope it is worth a little of bit of something to you as
well...
On Thursday 10 of June 2010 00:14:29 Rich Shepard wrote:
I thought that I could use LiDAR data within grass, but the 6.4
r.in.gdal man page does not include that format. Is this the wrong module
for these data?
There are two topographic quadrangle files that cover the project
drainage basin, and the data DVDs cost $200 each. I want to make high
resolution DEMs of the project basin and try to determine flood elevations
for different storm events from those. According to the data source, "All
data are format specific to ESRI GIS format. Data must be viewed using
specialty software capable of viewing .shp, geotif, and ESRI grid
formats."
I suppose that r.in.gdal will import the .shp files. I've not worked
with geotif or ESRI grid formats so any experiences of you folks with
these formats and LiDAR data will be much appreciated.
Rich,
Geotiff is more than supported in the OSGeo world. And ESRI grid's I've
imported (and exported after some trial and error) successfully sometimes, not
worked frequently with such a format though.
See also [1][2][3]. But the grass-gis-lidar experts will chime in I bet...
My 2 drachmas [4] (kept some of the previous greek coins for any case... :-p),
Nikos
On Wed, Jun 9, 2010 at 6:14 PM, Rich Shepard <rshepard@appl-ecosys.com> wrote:
I thought that I could use LiDAR data within grass, but the 6.4 r.in.gdal
man page does not include that format. Is this the wrong module for these
data?
There are two topographic quadrangle files that cover the project drainage
basin, and the data DVDs cost $200 each. I want to make high resolution DEMs
of the project basin and try to determine flood elevations for different
storm events from those. According to the data source, "All data are format
specific to ESRI GIS format. Data must be viewed using specialty software
capable of viewing .shp, geotif, and ESRI grid formats."
I suppose that r.in.gdal will import the .shp files. I've not worked with
geotif or ESRI grid formats so any experiences of you folks with these
formats and LiDAR data will be much appreciated.
On Thu, Jun 10, 2010 at 12:14 AM, Rich Shepard <rshepard@appl-ecosys.com> wrote:
I thought that I could use LiDAR data within grass,
You can
but the 6.4 r.in.gdal
man page does not include that format. Is this the wrong module for these
data?
There is no format "Lidar" - in fact there are many formats related to
Lidar data:
- raw x,z,y,w points in ASCII tables (v.in.ascii)
- LAS format (LAS tools + v.in.ascii)
- other point based ASCII formats (v.in.ascii)
- points in 3D SHAPE format (vector, v.in.ogr)
- rasterized DSM in GeoTIFF or whatever (raster, r.in.gdal)
- ...
There are two topographic quadrangle files that cover the project drainage
basin, and the data DVDs cost $200 each. I want to make high resolution DEMs
of the project basin and try to determine flood elevations for different
storm events from those. According to the data source, "All data are format
specific to ESRI GIS format. Data must be viewed using specialty software
capable of viewing .shp, geotif, and ESRI grid formats."
So GRASS can do that.
I suppose that r.in.gdal will import the .shp files.
No, it is v.in.ogr.
I've not worked with
geotif or ESRI grid formats so any experiences of you folks with these
formats and LiDAR data will be much appreciated.
For GeoTIFF, use r.in.gdal.
To process Lidar point data, then use v.lidar.*.
The already mentioned wiki page may be helpful, too.
There are two topographic quadrangle files that cover the project drainage
basin, and the data DVDs cost $200 each. I want to make high resolution DEMs
of the project basin and try to determine flood elevations for different
storm events from those. According to the data source, "All data are format
specific to ESRI GIS format. Data must be viewed using specialty software
capable of viewing .shp, geotif, and ESRI grid formats."
That sounds like these are no raw LiDAR data but already processed
data. Raster grids, in this case the GeoTIFF and ESRI grid data, are
usually end products after processing LiDAR data, and it would be
interesting to know what was done there in order to judge if these
raster grids are suitable for the planned analysis. The shapefiles
might hold LiDAR point clouds that can be processed with the LiDAR
tools:
1. v.outlier
2. v.lidar.edgedetection
3. v.lidar.growing
4. v.lidar.correction
optionally now
v.surf.rst or v.surf.bspline to generate a raster DEM
More in the already mentioned wiki page and the v.lidar.* manuals.
LiDAR point clouds should be imported as a vector and not a raster if
they are supposed to be processed with the v.lidar.* tools. LiDAR
point clouds come in different ways depending on the preprocessing
done. Sometimes there are no multiple return rates, sometimes
information about multiple return rates is stored for each point
(emitted pulse) in an attribute table, sometimes each return rate
represents one point, sometimes multiple return rates are in different
vector layers e.g. shapefiles. The v.lidar tools want each return rate
as a separate point, i.e. some preprocessing might be required if you
want to use the v.lidar.* tools.
I've not worked with
geotif or ESRI grid formats so any experiences of you folks with these
formats and LiDAR data will be much appreciated.
For GeoTIFF, use r.in.gdal.
GDAL supports so many raster formats (>100 in 1.7.2) that chances are
pretty good that a given raster map can be imported by r.in.gdal.
That sounds like these are no raw LiDAR data but already processed data.
Raster grids, in this case the GeoTIFF and ESRI grid data, are usually end
products after processing LiDAR data, and it would be interesting to know
what was done there in order to judge if these raster grids are suitable
for the planned analysis.
I have the metadata files. The LiDAR data were processed and clipped to
standard 7.5" (1:24,000) topographic quad sheets. One is straight forward,
but the other quad is an amalgam of LiDAR data from 2004 and 2007 collected
under two or three different contracts with the city.
Considering that I've never before worked with these data, have a lot to
learn about them, and need to work with a drainage basin that is partly in
each of the two topo quads, I suspect that I would not be able to complete
terrain and hydrological modeling by next Tuesday. There appears to be too
much for me to learn in too short a time, since I'm working on two other
projects with this one.
Today I'll read up on LiDAR and make my decision tomorrow. If anyone wants
to see the metadata files to comment on the utility of the data I'll happily
pass them on.
