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Answer (Unmark)
1/18/17 2:07 PM
Hello to all,

in chapter 9.5 of the manual syntax of voxels are descripted. But, IDF is an binary file (right?) and is done by iMOD himself, if the user loads an asc-file into the imod manager.
How a (asc-)file with voxels has to be, so that iMOD is able to know, this are voxels?

My voxel-file has the data
x y z value for the middle of the volume.

RE: Voxel
Answer (Unmark)
1/20/17 4:57 PMas a reply to Angela P.
(issue is moved to Category: iMOD-GUI / User Questions)

Dear Angela,

There are actually two ways to make a grid into a voxel.

1. One by one in the GUI.
Load your IDF file into the iMOD manger.
Select the Map Info ('i') button.
Halfway the window you find the option Adjust Top/Bot.
There you can ad (different) values for the Top and Bot of the IDF.
This is described in paragraph "6.3 Map info".

2. Automatically starting from ASC files.
At this moment, voxels are often created directly from ASC files.
In that conversion process it is possible to add voxel information (vertical position).
For an explanation of this conversion, have a look at chapter 8.10, the CREATEIDF-Function.
Part of that function are some extra keyword allowing you to add z-values.
In case you start with IDF files, add a preprocessing step in the iMOD batch file creating temporally ASC files.

Kind regards,

RE: Voxel
Answer (Unmark)
1/30/17 9:40 AMas a reply to Frans Roelofsen.
Dear Frans,
thank you for answer.
I guess my question was not accurate enough. I don’t want to create voxels. I have them already. They are my database, my starting point for the geology.

I have for each point (center point of voxel) the coordinate x, y, z and a value for the parameter.
The way to go is vice versa: create the needed files for iMOD from a voxel data base.
(In difference to the attached pic, the hights of the voxels are not equistant.)

Kind regards
Attachments: voxel.docx (581.2k)
RE: Voxel
Answer (Unmark)
2/3/17 1:30 PMas a reply to Angela P.
Hello Angela,

Now I get the confusion.
In iMOD we define voxels as an IDF (grid) file with values AND a fixed horizontal position.
See for an example the voxel definition in chapter "3D Plot Settings".
So your question was: "How a (asc-)file with voxels has to be, so that iMOD is able to know, this are voxels?"
Only if your asc file is an ESRI ASCII Raster format you can load it into iMOD, give it a vertical z position to make it a voxel.

From your second e-mail I read that your starting pont is a database with x/y/z/ values which you want to use for geology.
So to start with, you perhaps like to show them in the iMOD 3D viewer.
My suggestion is to convert your database into an IPF file. Your database is probably an excel file with 4 columns (x/y/z/value)?
See chapter "9.7 IPF-files" to see how to create an IPF file from your own data.
After loading the IPF into the iMOD Manager, you can configure the IPF settings and set the Z-Coordinate to your z-value and color the points with your value.
Now it is ready to show in the 3D viewer.

As a next step you probably like to use the X/Y/Z/value information to create/interpolate into a spatial grid.
For that purpose, see if chapter "8.21 XYZTOIDF-Function" offers you the functionality you need.


RE: Voxel
Answer (Unmark)
2/3/17 2:26 PMas a reply to Frans Roelofsen.
Hi Frans,
Thank you for answer. My goal is to use the information comes from the voxels for the groundwater flow simulation.
I don't unterstand, how Your proposal with the chapter XYZTOIDF-Function should work.
There is written:
"Use this function to create an IDF from a plain data file(s) or IPF file(s) that contain x,y,z data at least.
The column (“z”) can contain any type of (real) data.

Please remember my attached figures, I have a 3D voxel stack, an ascii-file like that:
X Y Z kf
3490462.500610 5538137.502930 132.933655 3.909435
3490487.500244 5538137.501953 132.864136 3.945728
3490512.500000 5538137.501953 132.762909 4.009053
3490537.499939 5538137.501953 132.571320 4.090920
3490562.500000 5538137.501953 132.445007 4.188450

The value for each voxels in grid centred, so it is valid for the centre of the grid cell, moreover, the value is representative for the whole area of each voxel.
What I need to know, how to bring it into the model. According my information this is possible, but unfortunately I don't see the way.

Liebe Grüße
RE: Voxel
Answer (Unmark)
2/7/17 4:46 PMas a reply to Angela P.
Hi Angela,

You have three options:

a) try to modify your file such that you can arrange is like x,y,k for each z-interval and use the XYZTOIDF function to generate an interface per layer and then create a voxel out of it;
b) try to write a script (python)/program(fortran) to generate asc files per z-interval with k-values, or even better try to write the IDF file format directly, it is not very difficult;
c) ask me to extent the XYZTOIDF function with the ability to generate a voxel model directly out of your x,y,z,k file. In that case, we need to arrange something to cover this financially.

Kind regards,

Peter Vermeulen,