AI短編アニメ制作ガイド：物語・ショット・動き・音・編集まで

AI短編アニメは、巨大なプロンプト一つから完成映像を出す作業ではありません。物語を小さくし、承認できる静止画へ分解し、ショットごとに動かし、編集と音で再び一つの作品へ組み立てる制作工程です。モデルが向上しても、因果関係、画面方向、人物の同一性、演技、音のタイミングは制作者が管理します。

本記事ではオリジナル短編『最後の灯』を例にします。灯台技師ハナが、壊れたランタンドローンのコアを嵐の中で運び、消えた都市の灯台を再点灯する物語です。代表画像は完成キービジュアルで、以下の4枚はビート、ビジュアルバイブル、アニマティック、音響・編集という実制作資料としてつながります。

2026年7月29日に、OpenAI画像生成ガイド、Runway画像→動画ガイド、Google Cloud Veo 3.1プロンプトガイド、Adobe Fireflyキーフレーム資料、ElevenLabs効果音資料を確認しました。機能・料金・商用条件は変わるため、制作前に最新ポリシーを確認してください。

1. 生成前に6ビートで物語を固定する

短編では設定説明より変化が重要です。「誰が何を望み、何が阻み、どんな選択をし、最後に何が変わるか」を一文にし、日常・事件・決断・試み・危機・結果の6枚へ変換します。字幕なしで順番を説明できなければ、動画生成の前に物語を直す方が安く済みます。

画像制作プロンプト — 6ビート・ストーリーボード

Use case: identity-preserve
Asset type: landscape blog illustration for the story-design section of an AI short-animation guide
Input images: Image 1 is the approved key art and exact visual reference for Hana, the brass lantern drone, the storm city, lighthouse, palette, and hand-painted 2D animation style.
Primary request: Create a six-panel visual beat board for the same original short film, communicating a complete beginning-middle-end without written labels. Panel 1: Hana repairs the dim lantern drone in a small rooftop workshop. Panel 2: the city's lighthouse goes dark as a storm arrives. Panel 3: Hana runs across wet roofs carrying the drone. Panel 4: a violent gust nearly blows the drone away and Hana catches it. Panel 5: inside the beacon room she inserts the glowing drone core into the lighthouse mechanism. Panel 6: the beacon shines across calm water at dawn as Hana and the restored drone watch together.
Subject continuity: preserve Hana's warm brown skin, silver-white single braided ponytail, deep teal eyes, mustard scarf, cobalt cropped coat with two brass clasps, charcoal trousers, brown lace-up boots, round brass belt compass; preserve the spherical brass lantern drone with three petal fins and amber core.
Style/medium: same cinematic hand-painted 2D animation visual development as Image 1, clean cel shapes, restrained gouache texture, production storyboard color keys.
Composition/framing: 16:9 landscape, clean 3-by-2 grid of six equally sized cinematic panels with narrow dark gutters, readable thumbnail silhouettes, consistent left-to-right screen direction and geographic continuity.
Lighting/mood: progresses from warm workshop dusk to cold storm blue, then amber climax and pale sunrise; lighting continuity within each beat.
Constraints: exact same adult Hana and drone throughout; coherent story order; no redesign, no additional people; no text, letters, numbers, captions, arrows, logos, UI, watermark; all panels uncropped within outer canvas.
Avoid: photorealism, 3D render, childlike proportions, costume drift, mirrored compass or clasps, extra limbs, duplicated Hana inside a panel, random props, inconsistent lighthouse.

まず無音で理解できる版を作り、本当に必要な情報だけを台詞に残すと、リップシンクと翻訳の負担も減ります。

2. キャラクター・小道具・空間を一枚のビジュアルバイブルへ

正面ポートレート一枚だけでは複数ショットを維持できません。正面・側面・背面、表情、非対称ディテール、主要小道具、環境カラーキーをまとめます。各ショットはこの資料を参照し、物語上の変更でない限り衣装色、形、地理、時間帯を固定します。

OpenAIの画像ガイドは画像入力を使う生成・編集を説明しています。重要なのは参照数ではなく、同一性・小道具・環境・スタイルという役割を明示し、一度に一要素だけ変えることです。

画像制作プロンプト — ビジュアルバイブル

Use case: identity-preserve
Asset type: landscape blog illustration for the visual-bible section of an AI short-animation production guide
Input images: Image 1 is the approved Hana key art; Image 2 is the approved six-beat board. Use both only as identity, prop, environment, palette, and style references.
Primary request: Create one polished production visual-bible board containing three equal-scale full-body views of the same adult Hana (front, strict side, back), four small consistent head-expression studies (calm, alarmed, determined, relieved), one clean enlarged view of the spherical brass lantern drone with its three petal fins, and one small environment color key of the cliff-city lighthouse in storm light. Do not add written labels.
Subject continuity: exact warm brown skin, silver-white single braided ponytail, deep teal eyes, mustard-yellow scarf, cobalt cropped weatherproof coat with two brass clasps, charcoal trousers, brown lace-up boots, round brass compass at belt; exact spherical brass drone with three symmetrical petal fins and warm amber core.
Style/medium: same cinematic hand-painted 2D animation visual-development style, clean cel shapes with restrained gouache texture, professional model sheet and prop sheet.
Composition/framing: 16:9 landscape, organized production-board layout on a warm neutral paper background, full uncropped turnaround figures aligned on one ground line, expression row clearly separated, drone and environment key balanced on the right; generous margins.
Lighting/mood: flat neutral lighting on character and drone; the environment key alone uses cold storm blue and amber beacon light.
Constraints: do not redesign; preserve adult proportions, facial geometry, braid, coat clasps, scarf, belt compass and boots; no text, letters, numbers, arrows, logos, UI, watermark; no additional people; no cropped feet.
Avoid: photorealism, 3D render, chibi or childlike proportions, mirrored details, costume drift, extra limbs, duplicated accessories, cluttered background.

3. ショットリストとアニマティックで安く失敗する

完成画像から始めず、各ショットの目的、サイズ、カメラ、行動、開始・終了状態、想定音を記録し、粗いフレームを編集ソフトに入れます。目的は美しさではなく、情報とリズムです。

画像制作プロンプト — 8ショット・アニマティック

Use case: identity-preserve
Asset type: landscape blog illustration for the shot-design and animatic section of an AI short-animation production guide
Input images: Approved references define Hana, the lantern drone, lighthouse city, palette, and exact 2D animation style.
Primary request: Create a polished eight-panel grayscale-plus-color-accent animatic contact sheet for the same rooftop-to-lighthouse sequence. Show eight distinct film shots in story order: extreme wide storm city and dark lighthouse; workshop close-up of the drone core dimming; medium shot Hana deciding to go; low tracking shot of boots running across wet tiles; side wide shot of Hana jumping a roof gap with the drone; close-up of Hana catching the slipping drone; interior over-shoulder shot inserting the amber core into the beacon machine; final extreme wide dawn lighthouse beam over the sea. Use only restrained cobalt and amber accents over readable charcoal storyboard values.
Subject continuity: same adult Hana with warm brown skin, silver-white braid, mustard scarf, cobalt cropped coat, charcoal trousers, boots and belt compass; same spherical brass three-fin amber-core drone.
Style/medium: professional animation animatic frames, expressive cinematic storyboard drawing, clean values, selective hand-painted color accents, original production art.
Composition/framing: 16:9 landscape outer canvas, eight equal panels in a clean 4-by-2 grid with thin neutral gutters, each shot has a clearly different shot size but preserves screen direction, horizon logic and lighthouse geography; readable at thumbnail size.
Constraints: preserve character and prop identity; one coherent sequence; no written shot numbers, no text, letters, captions, arrows, logos, UI, watermark; no extra people.
Avoid: photorealism, 3D render, childlike proportions, costume drift, duplicate Hana within a panel, random camera-axis reversal, extra limbs, cluttered panel borders.

尺はショット構造を決めた後、サービス設定で選びます。完成ランタイムを文章へ押し込むより、一回の生成に一つの主要動作を任せます。

4. 静止画は外見、動画プロンプトは時間を担当する

Runwayの現行ガイドでは、入力画像が構図・主体・照明・スタイルをすでに定めるため、画像→動画テキストは主体、環境、カメラ、方向、進行に集中します。重要動作から始め、結果を見て一要素ずつ追加します。入力のモーションブラーや風向きが指示と衝突すると動画で拡大されます。

動画制作プロンプト — 静かな感情演技

Locked medium close-up inside the rooftop workshop. The engineer steadies the dim lantern drone with both hands, watches its amber core flicker, takes one controlled breath, then lifts her eyes toward the lighthouse outside the rain-streaked window. Her worried expression settles into determination. Loose silver hair strands and the end of her mustard scarf respond softly to the draft; tiny brass fins tremble and stop. The camera remains still, with only a gentle focus shift from the failing core to her eyes. Continuous seamless shot, restrained acting, natural hand contact, no cut.

動画制作プロンプト — 屋根上アクション

A side-tracking camera moves with the engineer as she runs across wet roof tiles while cradling the lantern drone. Her boots make firm contact and spray small arcs of rainwater; her braid, scarf, coat hem, compass, and the drone fins trail with delayed secondary motion in the same wind direction. She compresses into one decisive jump over a narrow gap, lands with visible weight, regains balance, and continues toward the lighthouse. Stable horizon, coherent left-to-right screen direction, physically plausible momentum, continuous seamless shot.

動画制作プロンプト — 開始・終了フレームの灯台点灯

Animate one continuous transition between the supplied first and last frames. The engineer seats the glowing brass core into the beacon mechanism and twists it until the gears engage. The drone fins fold inward; warm amber light travels through concentric glass rings, grows into a powerful beam, and sweeps across the rain-dark sea. The storm rain softens as the room changes from cold blue to warm gold. The camera performs a slow restrained arc around her shoulder and settles on the same final composition. SFX: close metal latch, rising mechanical hum, deep gear engagement, rain against glass, distant ocean. No dialogue, no cut, preserve identity, geometry, light direction, and screen space.

GoogleのVeoガイドは撮影、主体、行動、文脈、スタイルと雰囲気を分け、参照画像と最初・最後のフレームを使うワークフローを説明します。Adobe Fireflyも静止画を開始・終了の固定点にできます。補間前にレンズ、カメラ高、照明、人物サイズが互換か確認してください。

5. 音を早く設計し、最終編集で映像とロックする

音は低コストでスケールを大きくします。台詞、フォーリー、環境音、効果音、音楽を別トラックにし、アニマティック段階で仮音を置きます。ElevenLabsの公式資料も、複雑な一括音より個別効果音を作って編集ソフトで組み合わせる方法を勧めます。雨、足音、金属ラッチ、歯車の共鳴が動きに重さを与えます。

画像制作プロンプト — 音響・編集・最終検査ボード

Use case: identity-preserve
Asset type: landscape blog illustration for the sound-design, edit, and final-QA section of an AI short-animation production guide
Input images: Approved references define Hana, the lantern drone, beat order, visual bible, lighthouse geography, palette, and exact hand-painted 2D animation style.
Primary request: Create a cinematic sound-and-edit production board without written labels. A large central finished frame shows Hana inside the lighthouse beacon room inserting the glowing lantern drone core into the mechanism while the first golden beam ignites. Around it are four smaller inset detail frames that visually represent separate audio and edit layers: rain striking a metal window and wind-blown scarf; boots landing heavily on wet roof tiles; close-up of the brass drone fins vibrating with a warm mechanical hum; giant beacon gears engaging with a resonant pulse. Along the bottom, include a purely visual filmstrip of five tiny continuity thumbnails progressing from storm darkness to sunrise, accompanied by abstract clean waveform shapes in matching colors, but no UI text or numbers.
Subject continuity: exact same adult Hana, warm brown skin, silver-white single braid, teal eyes, mustard scarf, cobalt coat with two brass clasps, charcoal trousers, boots, belt compass; exact spherical brass three-fin amber-core drone.
Style/medium: premium original 2D animation production art, clean cel shapes, restrained gouache texture, cinematic color finish, sophisticated editorial contact-sheet design.
Composition/framing: 16:9 landscape, dominant central frame, four balanced detail insets, narrow gutters, bottom filmstrip and abstract waveform motifs; clean hierarchy and safe margins for 1024x576.
Constraints: preserve character, costume, prop and environment identity; no written text, letters, numbers, captions, logos, interface labels, brand marks, watermark; no extra people; no copyrighted elements.
Avoid: photorealism, 3D render, childlike proportions, costume drift, random electronics, illegible clutter, extra limbs, inconsistent light direction.

生成クリップをすべて使う必要はありません。最もつながる候補だけを選び、共有フレームの重複を切り、必要な場所だけ安定化、速度、色を調整します。可能なら台詞なしマスターを先に完成させると、字幕と多言語音声を管理しやすくなります。

失敗したショットだけ戻す品質ゲート

結論：短編は生成ではなく承認の連鎖

品質を作るのは最長プロンプトではなく、小さな決定の順序です。ログラインとビートが物語、ビジュアルバイブルが同一性、アニマティックがリズムを固定します。その後一ショットずつ動かし、音と編集で接続すれば、失敗部分だけを交換できます。

最初は登場人物1人、場所1〜2か所、主要小道具1個、台詞0〜2行に限定してください。完成作品の制作資料と承認フレームは、無関係な生成画像の山より強い次回資産になります。

参考資料

• OpenAI — Image generation guide
• Runway — Image to Video Prompting Guide
• Google Cloud — The ultimate prompting guide for Veo 3.1
• Adobe Firefly — Create cinematic video from prompts and keyframes
• ElevenLabs — Sound effects guide

生成フレームには誤りがあり得ます。実在人物の顔・声、著作権キャラクター、音楽、参照画像の同意と利用権を確認し、公開前に人が全編を検査してください。