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My data is indeed a point cloud from bathymetry data so I can understand the problems you outlined so I will be happy to create 3d output from the multiple slicing method of r.to.rast3. I have only previously set a 2d region which all points lie within but am unsure how to set a 3d region?<BR> <BR> I 'successfully' ran the v.vol.rst command with my DOC data by specifying the w column as you suggested though it turns out the data is not sufficient in terms of density and it does in fact say points are outside 2d/3d region.<BR> <BR>Apologies for all these questions. I am still new to GRASS. <BR><BR>> Date: Thu, 21 Aug 2008 12:37:40 +0100<BR>> From: benjamin.ducke@oxfordarch.co.uk<BR>> To: i.summers@hotmail.co.uk<BR>> Subject: Re: [GRASS-user] displaying volumes from xyz vector in nviz<BR>> <BR>> If what you are after is the actual shape of the loch in voxel space:<BR>> that is not easy to do with current GRASS tools.<BR>> I do not know what your input data looks like, but I assume it is a<BR>> point cloud derived from bathymetry data? If so, then what you have<BR>> is a cloud of point describing the exterior hull of the loch. In order<BR>> to convert this to a voxel object, GRASS would need to be able to first<BR>> construct the polygonal hull using these points and then convert that<BR>> to a voxel representation. This is not currently possible and would<BR>> require someone to put some serious effort into creating a module<BR>> with the capability to convert 3D vector polygons to volumetric voxel<BR>> representations.<BR>> <BR>> I have never heard about the 'position not in queue' message. No idea<BR>> what is going wrong there.<BR>> <BR>> v.vol.rst should work fine if you use the 'wcolumn=' option to specify<BR>> the name of the attribute you want to interpolate.<BR>> <BR>> Have you set the 3D region extents correctly to cover your 3D input<BR>> data and produce the number of slices you want?<BR>> <BR>> Ben<BR>> <BR>> ian summers wrote:<BR>> > Hello Ben,<BR>> > <BR>> > Thank you for your suggestion but when I attempt to run r,to.rast3 I get <BR>> > the 'position not in queue' message again. I ran v.kernel on the <BR>> > respective slices with st deviation of 5 leaving all other parameters as <BR>> > they were. Was this correct? Having used the v.info command the layers <BR>> > are 3D. Essentially what I am trying to achieve is a volume cube of loch <BR>> > lomond from x, y, z coordinates. <BR>> > <BR>> > I also have dissolved organic carbon data which i was hoping to display <BR>> > volumetrically within this that has x, y, z, DOC columns. I ran <BR>> > v.vol.rst but it says w column not supported. my data here is:-<BR>> > <BR>> > INTEGER/cat<BR>> > > > > INTEGER/Id<BR>> > > > > DOUBLE PRECISION/X<BR>> > > > > DOUBLE PRECISION/Y<BR>> > > > > DOUBLE PRECISION/Z<BR>> > > > > DOUBLE PRECISION/DOC<BR>> > <BR>> > My main focus is the volume cube of loch lomond. The DOC would be a bonus.<BR>> > <BR>> > Ian<BR>> > <BR>> > > Date: Thu, 21 Aug 2008 09:55:07 +0100<BR>> > > From: benjamin.ducke@oxfordarch.co.uk<BR>> > > CC: grass-user@lists.osgeo.org<BR>> > > Subject: Re: [GRASS-user] displaying volumes from xyz vector in nviz<BR>> > ><BR>> > > To generate a volumetric model of your point data, you need to use<BR>> > > an algorithm that can interpolate an attribute in 3D space.<BR>> > ><BR>> > > To start with, you need to make sure that your input points map is<BR>> > > actually a 3D geometry, not just 2D points with X,Y and Z attributes<BR>> > > attached (us v.info to find out).<BR>> > ><BR>> > > v.to.rast3 simply takes the 3D point positions and creates a single<BR>> > > voxel value at every point location in the input map. Most likely, this<BR>> > > is not what you want and you should look into v.vol.rst instead.<BR>> > ><BR>> > > The question then is WHAT to interpolate. In your attribute table list<BR>> > > below, I cannot see an attribute that could actually be used for<BR>> > > interpolation. The only thing you have are integer categories.<BR>> > ><BR>> > > If you want to show point density in 3D: there is currently no GRASS<BR>> > > module to calculate that. So the only thing you can do is calculate<BR>> > > density for 2D slices at different Z ranges separately (use v.select<BR>> > > to query out points for each Z range, then run v.kernel on them) and<BR>> > > stack the resulting 2D raster maps on top of each other to form a voxel<BR>> > > cube using r.to.rast3.<BR>> > ><BR>> > > Ben<BR>> > ><BR>> > ><BR>> > > ian summers wrote:<BR>> > > > Dear all,<BR>> > > ><BR>> > > > I have a vector point file and have tried to run the program <BR>> > v.to.rast3<BR>> > > > though in the 'column name' section I am unsure what to enter? the<BR>> > > > column attributes for the data are as follows.<BR>> > > ><BR>> > > > > INTEGER/cat<BR>> > > > > INTEGER/Id<BR>> > > > > DOUBLE PRECISION/X<BR>> > > > > DOUBLE PRECISION/Y<BR>> > > > > DOUBLE PRECISION/Z<BR>> > > ><BR>> > > > I have tried entering cat, id and z in this box but in the output I<BR>> > > > receive the message 'position not in queue'.<BR>> > > ><BR>> > > > I have also tried to create the volume using r.to.rast3 and though it<BR>> > > > appears as though a file is created when it comes to display in nviz<BR>> > > > only a plain 2D white tile appears. The values in my Z column are<BR>> > > > negative as I am modelling a lake. I am unsure whether this holds any<BR>> > > > bearing on outcome.<BR>> > > ><BR>> > > > Hope someone can help.<BR>> > > ><BR>> > > > Ian Summers<BR>> > > ><BR>> > > ><BR>> > > > <BR>> > ------------------------------------------------------------------------<BR>> > > > Win £3000 to spend on whatever you want at Uni! Click here to WIN!<BR>> > > > <http://clk.atdmt.com/UKM/go/101719803/direct/01/><BR>> > > ><BR>> > > ><BR>> > > > <BR>> > ------------------------------------------------------------------------<BR>> > > ><BR>> > > > _______________________________________________<BR>> > > > grass-user mailing list<BR>> > > > grass-user@lists.osgeo.org<BR>> > > > http://lists.osgeo.org/mailman/listinfo/grass-user<BR>> > ><BR>> > ><BR>> > > --<BR>> > > Benjamin Ducke<BR>> > > Senior Applications Support and Development Officer<BR>> > ><BR>> > > Oxford Archaeology Ltd<BR>> > > Janus House<BR>> > > Osney Mead<BR>> > > OX2 0ES<BR>> > > Oxford, U.K.<BR>> > ><BR>> > > Tel: +44 (0)1865 263 800 (switchboard)<BR>> > > Tel: +44 (0)1865 980 758 (direct)<BR>> > > Fax :+44 (0)1865 793 496<BR>> > > benjamin.ducke@oxfordarch.co.uk<BR>> > ><BR>> > ><BR>> > ><BR>> > ><BR>> > > ------<BR>> > > Files attached to this email may be in ISO 26300 format (OASIS Open <BR>> > Document Format). If you have difficulty opening them, please visit <BR>> > http://iso26300.info for more information.<BR>> > ><BR>> > > _______________________________________________<BR>> > > grass-user mailing list<BR>> > > grass-user@lists.osgeo.org<BR>> > > http://lists.osgeo.org/mailman/listinfo/grass-user<BR>> > <BR>> > <BR>> > ------------------------------------------------------------------------<BR>> > Find out how to make Messenger your very own TV! Try it Now! <BR>> > <http://clk.atdmt.com/UKM/go/101719648/direct/01/><BR>> <BR>> <BR>> -- <BR>> Benjamin Ducke<BR>> Senior Applications Support and Development Officer<BR>> <BR>> Oxford Archaeology Ltd<BR>> Janus House<BR>> Osney Mead<BR>> OX2 0ES<BR>> Oxford, U.K.<BR>> <BR>> Tel: +44 (0)1865 263 800 (switchboard)<BR>> Tel: +44 (0)1865 980 758 (direct)<BR>> Fax :+44 (0)1865 793 496<BR>> benjamin.ducke@oxfordarch.co.uk<BR>> <BR>> <BR>> <BR>> <BR>> ------<BR>> Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information.<BR>> <BR><BR><br /><hr />Get Hotmail on your mobile from Vodafone <a href='http://clk.atdmt.com/UKM/go/107571435/direct/01/' target='_new'>Try it Now!</a></body>
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