How do Kling motion control (reference video) and the brush-based motion paths work: inputs, orientation modes, durations, limits and failure modes?

Problem. Directing a character's body and face movement with a reference clip instead of text. Conditions. Kling 2.6/3.0 motion control as exposed by fal, Replicate and Kling's own guide (hosted, proprietary). Method. (1) Reference-video motion control (fal 2.6 endpoint): image_url (character image: clear body proportions, avoid occlusion, occupy over 5% of the image), video_url (realistic character with visible upper body or full body including head), character_orientation = 'image' (keeps the image's pose and facing; max 10 s; good for camera-movement goals) or 'video' (transfers motion and orientation literally; max 30 s; for dance and choreography), optional prompt, keep_original_sound. (2) The prompt is scene-setting, not motion: describe identity, environment and style; over-describing motion is the most frequent error. (3) Kling's guide: motion can come from an uploaded video or a motion library; VIDEO 3.0 adds element binding to improve facial consistency across angles and occlusion. (4) Brush mode (Replicate readme): paint paths on up to six elements, with a static brush for areas that must stay still; start the path inside the element; one element at a time; reference videos of 3 to 30 s for dance or martial arts. Failure modes. Poor reference video quality or occlusion cannot be fixed in the prompt; character/reference mismatch (e.g. formal outfit with athletic motion) causes inconsistency; wrong orientation mode (image mode on complex dance, video mode on simple portraits adding rotation); hands and fine details can be blurry; very fast or complex motion is hard. Limitations. Vendor/third-party guides; no measurements; pricing not recorded; foot sliding and limb swaps are not discussed in these pages. Version/date. fal guide (no date), Kling guide Mar 5, 2026; fetched 2026-10-23. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Third-party hosting pages plus the vendor's guide; model behaviour not tested. Details differ between 2.6 and 3.0. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://fal.ai/learn/devs/kling-video-2-6-motion-control-prompt-guide",
      "note": "API Parameters; API Parameters; Character Orientation Modes; Character Orientation Modes; Structuring Effective Prompts; Common Failure Modes; Common Failure Modes; Motion Control; About; How it works; Tips; Limitations"
    },
    {
      "url": "https://kling.ai/quickstart/motion-control-user-guide",
      "note": "API Parameters; API Parameters; Character Orientation Modes; Character Orientation Modes; Structuring Effective Prompts; Common Failure Modes; Common Failure Modes; Motion Control; About; How it works; Tips; Limitations"
    },
    {
      "url": "https://replicate.com/kwaivgi/kling-v2.6-motion-control",
      "note": "API Parameters; API Parameters; Character Orientation Modes; Character Orientation Modes; Structuring Effective Prompts; Common Failure Modes; Common Failure Modes; Motion Control; About; How it works; Tips; Limitations"
    }
  ]
}