RelativeTransform

The brief BMD table describes a second image input participating in warp/distort and a pivot determined relative to pixel data. The old single-Image-Input description was incomplete. The table does not specify the second-input equation, native name, color or disconnected behavior.

In the diagrams Input means the main image and Control Image the second image path; ControlImage and the compact Control caption are semantic reference labels. White distinguishes the auxiliary branch in this article and is not claimed to be a verified Resolve socket color.

The first three exercises feed one known RGBA source into both image branches. This preserves the documented two-input setup and allows study of Center Type, channel and transform without guessing a separate control-map encoding. A different second map requires a separate native test.

Bounding Box uses the bounds of selected content, while Weighted Pixels accounts for channel-value distribution. A bounds center and weighted center can differ on an asymmetric pattern. Inspect alpha separately from luminance: opaque and empty backgrounds provide different data.

Range Low/High restrict participating values. A 0.1–1 range excludes zero background on the alpha-silhouette test. Exact boundary inclusion and empty-selection behavior are not established by the PNGs; do not promise automatic recovery from an unsuitable channel.

Pivot X/Y specify an additional anchor relative to the detected center, while Center X/Y control placement. Changing them equally is not equivalent: rotation and scale reveal the difference. Begin with Pivot 0/0 and Center 0.5/0.5, then change one level at a time.

Size X and Size Y controls directions independently; Size and Aspect separates overall size from proportions. Render provides Warp, Under-Sample Resolution, Filtering and Edges. Undersampling does not repair an unstable center; quality changes do not replace clean analysis input.

The tool analyzes current content and is not a tracker maintaining object identity across frames. Another bright region, alpha changes or range changes can move the anchor. For stable animation, inspect all frames with neutral rotation and scale first.