# Affine transformation

Applies an affine transformation to the dataset. This can be used to translate, scale, rotate, or shear the particles, the simulation cell, and/or surface meshes. The transformation can either be specified directly as a 3 x 3 matrix plus a translation vector, or by prescribing a target simulation cell to which the old cell and its content are mapped.

Given the 3 x 3 linear transformation matrix M and the translation vector t, the new position x' of a particle at the old position x is computed as x' = M⋅x + t. Vectors are column vectors in this notation.

The Enter rotation button opens a dialog box that lets you enter an axis and a rotation angle. OVITO computes the corresponding transformation matrix for you.

## Parameters

Transform simulation cell

  Controls whether the simulation cell is transformed.

Transform particle positions

  Controls whether the transformation is applied to the particle coordinates. You can select which particles should be affected by the modifier: All particles or only the currently selected ones.

Transform vector properties

  Controls whether certain vectorial properties of particles are transformed too. If selected, the values of the following vector properties will be transformed by the linear part of the transformation: Velocity, Force, Displacement.

Transform surface mesh

  Controls whether the transformation is applied to the surface mesh (if one exists). Surface meshes are typically created by the Construct surface mesh modifier.

Transformation matrix - Rotate/Scale/Shear

  The 3x3 matrix specifying the linear part of the affine transformation.

Transformation matrix - Translation

  The translation that is added after multiplying positions with the linear transformation matrix.

Transform to target box

  Three vectors defining the target simulation cell. The modifier will dynamically calculate the transformation based on this target cell shape and the current input simulation cell.