Hello Ben,
Thank you for your suggestion but when I attempt to run r,to.rast3 I get the ‘position not in queue’ message again. I ran v.kernel on the respective slices with st deviation of 5 leaving all other parameters as they were. Was this correct? Having used the v.info command the layers are 3D. Essentially what I am trying to achieve is a volume cube of loch lomond from x, y, z coordinates.
I also have dissolved organic carbon data which i was hoping to display volumetrically within this that has x, y, z, DOC columns. I ran v.vol.rst but it says w column not supported. my data here is:-
INTEGER/cat
INTEGER/Id
DOUBLE PRECISION/X
DOUBLE PRECISION/Y
DOUBLE PRECISION/Z
DOUBLE PRECISION/DOC
My main focus is the volume cube of loch lomond. The DOC would be a bonus.
Ian
Date: Thu, 21 Aug 2008 09:55:07 +0100
From: benjamin.ducke@oxfordarch.co.uk
CC: grass-user@lists.osgeo.org
Subject: Re: [GRASS-user] displaying volumes from xyz vector in nvizTo generate a volumetric model of your point data, you need to use
an algorithm that can interpolate an attribute in 3D space.To start with, you need to make sure that your input points map is
actually a 3D geometry, not just 2D points with X,Y and Z attributes
attached (us v.info to find out).v.to.rast3 simply takes the 3D point positions and creates a single
voxel value at every point location in the input map. Most likely, this
is not what you want and you should look into v.vol.rst instead.The question then is WHAT to interpolate. In your attribute table list
below, I cannot see an attribute that could actually be used for
interpolation. The only thing you have are integer categories.If you want to show point density in 3D: there is currently no GRASS
module to calculate that. So the only thing you can do is calculate
density for 2D slices at different Z ranges separately (use v.select
to query out points for each Z range, then run v.kernel on them) and
stack the resulting 2D raster maps on top of each other to form a voxel
cube using r.to.rast3.Ben
ian summers wrote:
Dear all,
I have a vector point file and have tried to run the program v.to.rast3
though in the ‘column name’ section I am unsure what to enter? the
column attributes for the data are as follows.INTEGER/cat
INTEGER/Id
DOUBLE PRECISION/X
DOUBLE PRECISION/Y
DOUBLE PRECISION/ZI have tried entering cat, id and z in this box but in the output I
receive the message ‘position not in queue’.I have also tried to create the volume using r.to.rast3 and though it
appears as though a file is created when it comes to display in nviz
only a plain 2D white tile appears. The values in my Z column are
negative as I am modelling a lake. I am unsure whether this holds any
bearing on outcome.Hope someone can help.
Ian Summers
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