Helmert Transformation

Transforms the building element placements using four parameters (x,y,z, and rotation), Helmert Transformation. You need to understand how the Helmert transformation works to use this tool. Usually, the Helmert transformation is used for transforming the model into the project site coordinates.

The transformation is calculated based on the difference between the First Model Point and the First Reference Point.

The First Model Point and Second Model Point define a line. The First Reference Point and Second Reference Point define another line. The rotation is calculated from the difference between these two lines. 

The first Model Point also defines the pivot point for the possible rotation.

Note that Simplebim’s Helmert Transformation never scales the model. This also means that your second points don't necessarily have to be the exact matching points, as long as they correctly define the matching lines from both coordinate systems.

Settings

Objects to Move

Select Object Class, Group, Group Category, Top Most, or Part-level objects. If you input site objects, the site object's coordinate system is changed. If you input building elements, their coordinate system is changed. Usually, you want to move the whole model. If so, input either the site or project objects.

First Model Point

Type in, copy from the clipboard, or pick from 3D the first point.

Second Model Point

Type in, copy from the clipboard, or pick from 3D the second point.

First Reference Point

Type in, copy from the clipboard, or pick from 3D the first reference point. Usually, these are the coordinates for the matching point for the First Model Point from your project's site coordinate system.

Second Reference Point

Type in, copy from the clipboard, or pick from 3D the first reference point. Usually, these are the coordinates for the matching point for the Second Model Point from your project's site coordinate system.

Move Objects with Their Containers

IFC has a hierarchical placement system. Site's coordinate system is relative to the project's coordinate system, building's system is relative to the site's system and so on...

With the Helmert Transformation tool, you can either change the so-called local coordinate system's coordinates or move everything related to that coordinate system at once. 

On

Usually, you want to keep Move Objects with Their Containers on. This will move everything related to the objects you are moving with it. For example, if you move the site object 10 meters along the x-axis, everything assigned to that site in the model tree will also move 10 meters along the x-axis.

Off

This is a theoretical option for Helmert Transformation. However, in special situations you want to only change the local placement coordinates of an object. For example, there are applications, which don't handle well that the site object's coordinates are far from the building elements coordinates. In this case you could turn Move Objects with Their Containers off, can edit only the site's coordinates. Everything assigned to it in the model tree, will stay in the same coordinates in the world coordinate system. This is a ‘hidden’ operation that only affects the internal placement structures of your model, not the placements of any objects in 3D.