Mastering Contact Shadows for Glass Bottles in Nano Banana 2

When generating product photography with AI, one of the most frequent visual errors is the "floating" effect. This occurs when a transparent object, such as a glass bottle, lacks a connection to the surface it rests upon. Without a proper contact shadow, the brain perceives the object as hovering in mid-air rather than sitting on a table or shelf. Nano Banana 2 offers powerful text-to-image and image-to-image workflows that allow users to correct this specific issue by applying precise prompt instructions. By focusing on the interaction between light, transparency, and the surface plane, you can create convincing, grounded imagery.

The core challenge with glass is its dual nature: it reflects light while also allowing it to pass through. A standard shadow often looks too dark or solid, which contradicts the physics of clear material. Instead, the goal is to generate a subtle, localized darkening at the base where the bottle meets the surface. This technique, known as a contact shadow, anchors the object without obscuring the transparency of the glass itself. Nano Banana 2, identified by Google as Gemini 3.1 Flash Image, is capable of interpreting these nuanced lighting requests when guided correctly.

Why Contact Shadows Matter for Product Visualization

In professional product visualization, realism is paramount. A glass bottle that appears to float breaks the viewer's immersion immediately. This is particularly critical for e-commerce and marketing materials where trust in the product presentation influences purchasing decisions. The absence of a contact shadow suggests the object has no weight or physical presence, making the image look like a digital composite rather than a photograph.

Nano Banana 2 allows users to bypass this common AI limitation by explicitly instructing the model to render the shadow only at the point of contact. Unlike general shading, which might darken the entire bottom half of an object, a contact shadow is a thin, sharp line of darkness that follows the contour of the bottle's base. This distinction is vital for maintaining the illusion of transparency. When the prompt focuses on this specific area, the AI understands that the rest of the bottle should remain clear and reflective, preserving the material properties of the glass.

It is important to note that prompt instructions describe desired outcomes but do not guarantee identity, label, object, or typography preservation. If your image contains specific branding, the AI may alter text or logos while attempting to fix the lighting. Therefore, these techniques are best used for generic unbranded products or when the focus is strictly on the form and lighting rather than specific commercial details. For users prioritizing speed and cost over complex multi-turn editing, Nano Banana 2 Lite (Gemini 3.1 Flash Lite Image) is an option, though it is not optimized for multiple reference inputs or sequential editing workflows.

Five Materially Different Prompt Strategies

To achieve the best results, you must tailor your prompts to the specific context of your image. Below are five distinct examples of how to phrase your request to Nano Banana 2. These are examples of prompt structures; they illustrate how to guide the model toward the desired lighting outcome.

Example 1: The Direct Instruction Approach

Prompt: "A clear glass water bottle on a wooden table. Add a sharp, subtle contact shadow directly under the base of the bottle to ground it. Do not add a full drop shadow." When it helps: Use this when you have a generated image where the bottle is clearly floating and you need a quick fix. It works well for simple scenes with minimal background clutter. Adjustment: If the shadow is too dark, add "very faint" before "contact shadow."

Example 2: The Lighting Physics Approach

Prompt: "Photorealistic studio shot of a transparent glass perfume bottle. Render a realistic contact shadow at the interface between the glass base and the white marble surface. Ensure the shadow is soft but defined, mimicking natural occlusion." When it helps: Ideal for high-end product shots where the surface texture (like marble) needs to interact naturally with the shadow. This approach emphasizes the material interaction. Adjustment: Specify the light source direction if the shadow falls incorrectly, e.g., "light coming from top left."

Example 3: The Negative Constraint Approach

Prompt: "Glass soda bottle on a dark countertop. Include a grounding contact shadow at the bottom edge. Avoid any floating appearance, avoid large diffuse shadows, and keep the glass body fully transparent." When it helps: Useful when the AI tends to over-shadow the object or make the glass look opaque. Explicitly stating what not to do can refine the output significantly. Adjustment: Increase the emphasis on transparency by adding "high clarity" or "crystal clear."

Example 4: The Contextual Environment Approach

Prompt: "A sleek glass olive oil bottle resting on a rustic wooden cutting board. Generate a realistic contact shadow that conforms to the uneven texture of the wood at the base of the bottle." When it helps: Best for lifestyle photography where the surface is textured. This forces the AI to calculate how the shadow interacts with irregular surfaces rather than a flat plane. Adjustment: If the shadow looks too uniform, specify "shadow follows the grain of the wood."

Example 5: The Minimalist Abstract Approach

Prompt: "Isolated clear glass jar on a neutral grey background. Create a minimal, tight contact shadow ring around the base to anchor the object visually. No ambient occlusion elsewhere." When it helps: Perfect for catalog-style images where the background is plain and the focus is solely on the object's geometry. It prevents the AI from adding unnecessary environmental reflections. Adjustment: If the shadow is missing entirely, try "stronger grounding shadow."

Optimizing Your Workflow in Nano Banana 2

While Nano Banana 2 provides the tools to generate these realistic effects, understanding the model's capabilities is essential for success. The platform supports both text-to-image and image-to-image workflows, giving you flexibility in how you apply these prompts. You can start with a blank canvas or upload a reference image of a bottle that needs shadow correction.

Remember that Nano Banana 2 is powered by Gemini 3.1 Flash Image, which balances quality and performance. If you are working with complex scenes requiring multiple reference inputs or sequential edits, you might consider Nano Banana Pro (Gemini 3 Pro Image), as Nano Banana 2 Lite is not optimized for those specific advanced workflows. Always verify the available features on the official product pages, as model names and capabilities must not be presented as proof of identical features across all tiers.

For more information on the capabilities of this tool, visit Try Nano Banana. By mastering these prompt strategies, you can consistently produce high-quality images where transparent glass objects feel real, heavy, and perfectly grounded in their environment.

These prompt examples are illustrative. Results may vary based on the specific input image and current model behavior. There are no guarantees of specific outcomes, as AI generation involves probabilistic processes. However, by focusing on the specific mechanics of contact shadows, you significantly increase the likelihood of achieving a photorealistic result.