Vtu2Grid

Introduction

This utility rasterizes an existing 3D mesh at a given resolution. The result is a (quasi-)structured grid (consisting of hexahedral elements) with the same extent as the input mesh. Cell properties are mapped onto the grid (sampled at centre-points of each cube), while node properties are ignored. For large raster sizes, an undersampling of the original mesh is possible.

Usage

   Vtu2Grid  -i <input.vtu> -o <output.vtu> -x <floating point number>
             [-y <floating point number>] [-z <floating point number>]

Where:

   -i <input.vtu>,  --input <input.vtu>
     (required)  the 3D input mesh (*.vtu, *.msh)

   -o <output.vtu>,  --output <output.vtu>
     (required)  the output grid (*.vtu)

   -x <floating point number>,  --cellsize-x <floating point number>
     (required)  edge length of cubes in x-direction (longitude) or all
     directions, if y and z are not set

   -y <floating point number>,  --cellsize-y <floating point number>
     edge length of cubes in y-direction (latitude)

   -z <floating point number>,  --cellsize-z <floating point number>
     edge length of cubes in z-direction (depth)

The x/y/z-parameters determine the raster size. If only x is given, all raster cells will be (equilateral) cubes. If all three parameters are specified, the programme will create rectangular cuboid cells.

Simple example

Command:

Vtu2Grid -i input.vtu -o output.vtu -x 200

Command:

Vtu2Grid -i input.vtu -o output.vtu -x 100

Command:

Vtu2Grid -i input.vtu -o output.vtu -x 50

Command:

Vtu2Grid -i input.vtu -o output.vtu -x 50 -y 50 -z 10

Application

This utility can be used to convert complex unstructured 3D meshes with a numerically challenging geometry into simple, rasterized meshes. This will (significantly) increase the number of elements but prevents numerical issues during a subsequent simulation, thus exchanging a challenging model setup with a longer runtime. As such, the output mesh allows to quickly set-up a working model of region of interest to get first results that allow for informed decisions for a more realistic model using the unstructured input mesh.