How We Made an AI Portal Video with Nano Banana 2 and Seedance 2.5
A real Lemniscata AI project: our portal-themed YouTube Short. This case study will pair the finished video with the actual reference, generation prompt and production settings.
Step 1: Creating the source image
The opening image was generated with Nano Banana 2 on September 24, 2026. Confirmed settings: vertical 9:16, 768 × 1376 pixels, 1K output.
Original Nano Banana 2 prompt
Create one ultra-photorealistic vertical 9:16 cinematic opening frame for a premium future-technology commercial. Inside an expensive modern apartment, a solid raw-concrete wall contains a real full-height rectangular portal to a tropical beach. The portal is a genuine physical opening through the wall with realistic depth, perspective, wall thickness and shadows. It is not a screen, mirror, projection, painting or hologram. No door and no glowing portal frame. Capture the peak of an impossible action. One realistic 25-year-old woman is already halfway bursting backward from the tropical beach through the wall into the apartment. Her upper body and one leg are inside the room, while her other leg is still passing through the portal. She naturally struggles to regain balance after being pushed through by an ocean wave. Her pose clearly shows fast backward momentum. A dramatic but physically realistic splash of clear seawater follows her through the portal. Sharp suspended water droplets sparkle in the tropical sunlight. Water spreads across the lower foreground and wet oak floor without covering her face, the portal or the device. The image must instantly communicate that a woman has just emerged through a solid wall from a real beach. The woman has one distinctive consistent face, expressive brown eyes, realistic skin texture, minimal natural makeup and dark brown hair tied in a neat low ponytail. She wears an elegant beige trench coat over a plain white top, fitted black pants and clean white sneakers. Her coat and ponytail move naturally from the water and momentum. Her expression shows genuine surprise and excitement. She looks into the apartment, not at the camera. She must resemble a real actress caught during action, not a posing model. A palm-sized circular matte-black Portal Button is physically attached to the concrete wall directly to the right of the opening at chest height. It has one thin cyan-blue illuminated ring and a subtle central button. Premium minimalist industrial design, realistic materials, no screen, text, logo, floating controls or holograms. Clearly visible but secondary to the woman. The apartment has warm natural oak flooring, a raw-concrete feature wall, subtle premium furniture in neutral beige and charcoal colors and realistic architectural proportions. No futuristic decoration. The floor beneath the portal is wet with natural reflections and small pools of seawater. Inside the portal is a photorealistic tropical beach with turquoise ocean water, pale sand, warm sky, distant palm trees and realistic horizon depth. The beach continues naturally beyond the wall with correct spatial perspective and feels physically connected to the apartment. Vertical 9:16 composition for YouTube Shorts and TikTok. Camera at waist height, approximately 2.5 meters from the wall, cinematic medium-wide framing. The woman occupies the central-left area, her face clearly visible. The portal is fully understandable behind her and the Portal Button is visible on the right. Leave clean negative space near the top for text to be added later, but generate no text. Create strong depth: water droplets and floor reflections in the foreground, the woman in the middle ground and the beach through the wall in the background. Freeze the action at its most dramatic moment. Keep the woman’s face sharp. Use only subtle realistic motion blur on the fastest droplets and coat edges. Shot as if on an ARRI ALEXA 35 with a Cooke S8/i 32mm lens at T2.8. Cinematic HDR, natural depth of field, authentic skin tones, soft highlights, detailed shadows and premium commercial color grading. No fisheye distortion or excessive blur. Soft warm late-afternoon window light enters from camera-left. Bright tropical sunlight pours through the portal and creates physically accurate highlights and reflections on her face, coat, hair, water, wall and wet floor. Bright and immediately readable on a phone screen. Ultra-photorealistic live-action footage, expensive international technology commercial, high-budget invisible visual effects, realistic anatomy, skin, materials, water physics and motion. The portal must look fully integrated into a real apartment, not like AI art, illustration, fantasy, cyberpunk, glossy CGI or a video game. Only one woman. No duplicate people, extra limbs, malformed hands, incorrect fingers, distorted face, unnatural pose or floating feet. No glowing portal border, fantasy ring, sparks, lightning, smoke, debris, energy beams, machinery or holographic interface. No excessive neon. No text, captions, letters, logos, brands, watermarks or black borders. The final image must look like an unforgettable first frame of a real expensive commercial: a woman physically bursting through a solid apartment wall from a tropical beach, followed by real ocean water.
Step 2: Animating the image in Runway
The Nano Banana 2 image was uploaded to Runway and used as the exact first video frame. The selected generation model was Seedance 2.5.
Confirmed video settings: vertical 9:16, 720p resolution, 10-second duration, Keyframe mode, audio enabled and MP4 output.
Original Seedance 2.5 prompt
Create a 10.0-second ultra-photorealistic vertical cinematic video using the uploaded image as the exact first frame at 0.00 seconds. Continue the existing action immediately with no pause, freeze, fade-in, establishing shot, or reset. The video must be one seamless uninterrupted shot with no cuts, montage, time jumps, speed ramps, or camera teleportation. CORE CONTINUITY LOCK: Preserve the exact woman from the uploaded first frame: identical face, age, brown eyes, dark-brown ponytail, body proportions, beige trench coat, white top, black pants, and white sneakers. Preserve the exact apartment, concrete wall, oak floor, furniture, rectangular portal opening, beach, and circular matte-black Portal Button with its thin cyan ring. Do not redesign, move, resize, duplicate, or morph any of these elements. Only the destination visible through the fixed portal and its physically motivated light, wind, snow, water, and sound may change. The portal is a genuine opening through a solid wall with real depth and correct perspective, never a screen, mirror, projection, hologram, glowing fantasy ring, or flat image. The Portal Button stays attached to the exact same spot on the right side of the concrete wall. VISUAL STYLE AND CAMERA: High-budget live-action international technology commercial, invisible premium visual effects, not AI art and not glossy CGI. Shot as if on an ARRI ALEXA 35 cinema camera with a Cooke S8/i 32mm lens at T2.8, 24 fps, 180-degree shutter, cinematic HDR, natural motion blur, authentic skin texture, soft highlight roll-off, physically accurate shadows and reflections, realistic depth of field, and restrained premium color grading. The woman remains sharp and readable; only fast water droplets, coat edges, hair, snow, and feet receive natural motion blur. Use a controlled handheld-gimbal feel: subtle human weight, never shaky or floating. Begin with a short reactive dolly backward, then a smooth small arc toward camera-right, followed by a gentle forward push. Keep the woman, portal, and button readable. Maintain the original 9:16 composition and realistic lens perspective. BASE LIGHTING: The apartment retains the exact warm late-afternoon light from the uploaded image, with warm sunlight entering from camera-left. Every portal destination contributes physically accurate secondary light that falls across the woman's face, hair, coat, concrete wall, water, and wet floor. Lighting transitions smoothly without changing the apartment itself. SECOND-BY-SECOND ACTION: 0.00-1.25 — IMMEDIATE SCROLL-STOPPING HOOK: Start on the exact uploaded frame. The woman is already being thrown backward out of the tropical beach portal by a real ocean wave. Continue her existing momentum instantly. The raised leg comes naturally into the apartment, her planted sneaker slides slightly on the wet oak floor, and she regains balance without falling. Her coat, ponytail, arms, and body respond with realistic weight and inertia. The existing water splash continues forward and downward with physically accurate gravity, droplets, wet reflections, and small ripples across the floor. The camera reacts with a fast but controlled 25-centimeter dolly backward and a tiny natural tilt, as if the operator is surprised, while keeping her face, portal, and button visible. No frozen opening and no delay. Lighting: warm tropical sunlight through the portal creates moving highlights in the droplets and on the wet floor. Sound only: one sharp synchronized seawater splash, water hitting wood, wet sneaker friction, coat movement, natural ocean surf through the portal, and subtle apartment room reflections. No voice or music. 1.25-2.15 — CLEAR DEVICE ACTIVATION: The woman stabilizes, turns her attention to the black Portal Button, takes one quick believable step toward it, and clearly presses the center once with her right index finger. Her hand and fingers remain anatomically correct. The camera transitions into a smooth stabilized arc approximately 10 degrees toward camera-right so the physical button press is easy to understand, without losing the woman or portal. The cyan ring makes one restrained inward light pulse. No floating interface or hologram. Sound: precise premium mechanical click, a very short low electronic activation pulse, soft water dripping, and quiet room ambience. The activation pulse is a sound effect, not music. 2.15-3.75 — SNOWY ALPINE DESTINATION: Only the view inside the unchanged rectangular portal rapidly transforms from the tropical beach into a vast photorealistic snowy alpine landscape. The wall and portal geometry remain perfectly stable. Cold blue-white mountain light spills naturally into the warm apartment. A short realistic blast of cold air and fine snow enters through the opening. The woman's ponytail and coat move in the wind; she raises one forearm briefly to shield her face while reacting with genuine surprise. Snowflakes hit her coat and the wet floor, and a few begin melting. Her identity, clothes, and proportions never change. Camera: continue the same smooth small arc and begin a subtle forward push with believable parallax. Sound only: cold mountain wind, fine snow tapping the coat and floor, subtle fabric flutter, distant alpine atmosphere. No human vocalization. 3.75-4.30 — SECOND BUTTON PRESS: Without a cut, the woman makes one clear second press on the same fixed button. Keep her hand natural and the press visible. Sound: one synchronized mechanical click and the same restrained electronic pulse. 4.30-5.75 — NIGHTTIME MANHATTAN: Only the portal destination changes into a photorealistic nighttime Manhattan street with moving yellow taxis, wet asphalt, distant pedestrians, and realistic urban depth. No readable shop names, advertisements, logos, or license plates. Restrained amber, red, and cool city reflections travel naturally across the concrete wall, her face, coat, and wet floor. A warm city air current moves the bottom of her trench coat. She looks into the city with delighted disbelief. Camera: maintain the continuous gentle push; do not change lens, angle, or room geometry. Sound only: distant traffic, tires on wet asphalt, one soft faraway horn, subdued city ambience, and apartment room tone. No intelligible voices. 5.75-6.25 — THIRD BUTTON PRESS: She quickly presses the Portal Button a third time. The cyan ring produces the same subtle inward pulse. Sound: precise click and short low activation pulse. 6.25-7.45 — RETURN TO THE ORIGINAL BEACH: The portal returns to the exact same tropical beach shown in the uploaded first frame: identical turquoise water, sand, palm trees, horizon, sunlight direction, color, and perspective. Warm beach light immediately returns to the room and reflects across the wet floor. The woman smiles with excited determination, turns toward the portal, and takes two quick realistic steps. Her shoes contact the wet floor with proper traction and body weight. She jumps forward into the portal toward the beach. Her anatomy, face, ponytail, and clothing remain stable. Camera: a smooth energetic forward push follows her movement but remains inside the apartment and never passes fully through the wall. Sound only: ocean surf returns, two fast wet footsteps, fabric movement, and a sharp sneaker push-off. 7.45-10.00 — STORY-DRIVEN PERFECT LOOP: As she enters the beach, a powerful realistic ocean wave strikes her from the front and throws her backward through the portal into the apartment again. Her movement is forceful but safe and believable, not violent. Water follows her through the wall in the same direction as the opening splash. The camera reacts by smoothly dollying backward into the exact original framing. By 10.00 seconds, the woman's pose, facial direction, raised leg, coat movement, portal view, button position, tropical lighting, water shape and overall composition converge as closely as possible to the uploaded first frame at 0.00 seconds. End during continuing motion, with no pause, freeze, fade, or black frame, so the cut from 10.00 back to 0.00 is visually and audibly invisible. The final ocean impact and splash sound must connect naturally into the opening splash sound, creating a continuous audio loop. AUDIO RULES: Generate only synchronized diegetic sound effects caused by visible actions and environments: ocean splash, surf, water hitting wood, wet footsteps, coat and hair movement, button clicks, short restrained electronic activation pulses, mountain wind, snow particles, distant city traffic, and room ambience. Absolutely no music, soundtrack, beat, melody, singing, dialogue, narration, whispering, gasps, screams, laughter, human vocalizations, cinematic boom, or trailer sound. CRITICAL AVOIDANCE: No cuts, scene changes outside the portal, duplicate woman, extra people entering the apartment, face morphing, outfit changes, body distortion, extra limbs, malformed hands, sliding feet, floating objects, flicker, disappearing button, changing furniture, changing wall geometry, portal resizing, magical glowing border, sparks, lightning, smoke, debris, cyberpunk styling, oversaturated neon, excessive lens flare, cartoon physics, plastic skin, video-game appearance, text, subtitles, captions, logos, brands, watermarks, or black bars. The finished result must look like one real expensive commercial shot practically with a real actress in a real apartment, enhanced by seamless invisible visual effects.
The result
Approximately 37,000 YouTube views, reported by the creator on October 5, 2026. This is a dated snapshot, not a live counter or a promise of results for another video.
Production breakdown — editorial draft
Before publication, add the original reference image, exact model and generation settings, original prompt, revisions and editing steps. Check the YouTube player in the article preview and confirm the view count against the video or channel analytics. No reconstructed prompt is presented as the original production prompt.
Comments