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The Extract Transform Object gets its transform by looking at the points of two SOP geometries. The difference of these point clouds is projected into a rigid transform consisting of a rotation and translation, and this then becomes the transform of this object.
This extraction is very useful when you have baked geometry files which represent rigid motion and want to recover that rigid motion at object level.
The resulting transform may contain reflections that will invert normals if the object is close to planar. To resolve this, you can add extra marker points to the two objects, such as an Attribute Wrangle set to
addpoint(geoself(), @P + 0.1*@N); to prevent extraction of an inverted transform.
Path to the SOP geometry to use as the rest reference geometry.
Path to the SOP geometry to use as the goal geometry. The transform will transform the source geometry into the destination geometry.
Whether to use the motion of the point cloud.
Whether to use the rotation of the point cloud. This is always measured about the average of the points in the point cloud.
Set Wireframe Color
Use the specified wireframe color
The display color of the object
Viewport Selecting Enabled
Object is capable of being picked in the viewport.
Script to run when the object is picked in the viewport. See select scripts .
Cache Object Transform
Caches object transforms once Houdini calculates them. This is especially useful for objects whose world space position is expensive to calculate (such as Sticky objects), and objects at the end of long parenting chains (such as Bones). This option is turned on by default for Sticky and Bone objects.
See the OBJ Caching section of the Houdini Preferences window for how to control the size of the object transform cache.
Enable Constraints Network on the object.
Path to a CHOP Constraints Network. See also creating constraints.
You can you use the Constraints drop down button to activate one of the Constraints Shelf Tool. If you do so, the first pick session is filled automatically by nodes selected in the parameter panel.
This example shows how to parent geometry to a moving piece of geometry that is defined by a prebaked .bgeo sequence.
The following examples include this node.