[GRASS-user] r3.in.xyz

[Moritz Lennert]

On 27/06/18 03:59, Francois Chartier wrote:
> Hi,
> 
> I am working with a data set that consists of borehole logs with a Top 
> of a layer (layer 1) and the top of the underlying layer (layer 2) 
> (which is also the bottom of the overlying layer 1).  Everything in 
> between the elevation of top of layer 1 and top of layer 2 correspond to 
> a Layer 1 property.
> 
> The thickness of Layer 1 varies and this layer may not exist everywhere 
> (pinches out).  Above the Layer the property is different; in other 
> words the property only starts below the Top of layer 1 until the 
> underlying Top of the next layer.
> Not sure of the capabilities of the interpolation in Grass and working 
> with a very large data set (i cannot link every top of layers together), 
> my first approach was to create a each Layer property for every 
> elevation slice along each Borehole axis, interpolating soil properties 
> at every elevation between Boreholes.
> 
> I read on another forum that r3.in.xyz <http://r3.in.xyz> can 
> interpolate in 3D without a Property at every elevation slice,
> 
>   * while respecting the condition that above the Top of the layer 2,
>     the property corresponds to the Overlying top layer 1, and
>   * that the property is continuous until the next underlying layer 3 -
>     can someone confirm this?
> 
> To provide a bit of background, borehole data bases, identify the top of 
> layer as encountered when drilling downwards, and provide the elevation 
> of the next layer (pick); in between the soil property is the same, 
> however there is no data points.  When interpolating, while there is no 
> data point in between the two geological picks, the property should 
> still have weight in the interpolation process.
> 

I don't think r3.in.xyz is what you need. This module aggregates 3D 
point data into voxels.

You probably want to use something like r.to.rast3. This would mean 
interpolating each layer separately into 2D elevation maps and then 
assemble them into 3D using r.to.rast3.

Moritz