Fixing Missing Shadows on Transparent Products in Nano Banana 2

When working with transparent materials like glass bottles, plastic containers, or clear packaging, users often encounter a common visual artifact where the product appears to float above the background. This issue manifests as a complete absence of contact shadows or ambient occlusion at the base of the object. While Nano Banana 2 is capable of high-fidelity image generation, the physics of light passing through clear surfaces can sometimes confuse the model's rendering engine, leading to unrealistic compositions. This guide addresses the specific symptom of missing shadows on transparent product overlays and provides actionable steps to correct the effect.

Understanding the Symptom and Known Facts

The primary symptom involves a product that looks visually detached from its environment. Instead of resting naturally on a surface, the item hovers, lacking the darkening gradient or soft shadow that typically anchors an object to a ground plane. This is particularly noticeable with glass or plastic because these materials do not cast hard, opaque shadows like wood or metal; they rely on subtle refractions and contact points for realism.

It is important to distinguish between a software limitation and a prompt ambiguity. Google documents Nano Banana 2 as Gemini 3.1 Flash Image, which is a distinct model from Nano Banana Pro (Gemini 3 Pro Image) and Nano Banana 2 Lite (Gemini 3.1 Flash Lite Image). Each model has different optimization goals. For instance, Nano Banana 2 Lite is focused on speed and cost efficiency. It is explicitly noted that this version is not optimized for multiple reference inputs or multi-turn sequential editing. If you are experiencing persistent issues with complex lighting scenarios, switching to the standard Nano Banana 2 workflow may be necessary, as the Lite version might lack the nuanced reasoning required for complex material interactions.

Furthermore, prompt instructions describe desired outcomes but do not guarantee identity, label, object, or typography preservation. When troubleshooting missing shadows, it is crucial to remember that the AI interprets text literally. If the prompt does not explicitly define the relationship between the object and the surface, the model may default to a clean cutout style rather than a photorealistic integration.

Separating Plausible Causes from Model Limitations

Before attempting a fix, we must separate plausible user errors from inherent model behaviors. A frequent cause of floating products is the omission of environmental context in the prompt. If the input describes only the object without mentioning the surface it sits on, the AI has no geometric reference to calculate a shadow. Another plausible cause is the use of overly abstract descriptors like "floating" or "isolated," which directly contradict the goal of grounding the object.

However, some causes are related to the specific capabilities of the underlying models. As established by Google documentation, Nano Banana 2 Lite is not designed for complex multi-step edits. If a user attempts to add shadows in a second pass after generating a base image, the Lite version may fail to maintain consistency or interpret the new instruction correctly due to its focus on single-shot speed. Additionally, while the tool supports text-to-image and image-to-image workflows, the preservation of specific physical properties like transparency can vary based on the complexity of the scene. The model does not inherently know the physics of your specific product unless guided by detailed descriptive language regarding lighting and surface interaction.

Diagnosing the Issue Through Prompt Engineering

Diagnosing the problem usually requires analyzing the prompt structure. The AI needs explicit cues about the lighting environment and the surface texture. To diagnose if the issue is prompt-related, try removing any ambiguous terms and replacing them with concrete physical descriptions. Ask yourself: Does the prompt mention the table, floor, or counter? Does it specify the type of lighting, such as "softbox" or "natural sunlight," which creates softer, more realistic shadows?

If the diagnosis points to a lack of grounding information, the solution lies in enhancing the prompt's spatial awareness. You must instruct the model to render the contact point specifically. Do not assume the AI will infer the shadow automatically. Explicitly state that the object should have a "contact shadow" or "ambient occlusion" at the base. This directs the model to simulate the light blockage that occurs where two objects touch.

For users seeking to refine their approach, the prompt library offers example prompts that can serve as a starting point. These examples illustrate how to structure requests for specific outcomes. Remember that these are examples and may require adjustment based on your specific product. By studying these structures, you can learn how to articulate the need for depth and grounding without relying on generic terms.

Fixing the Effect with Targeted Instructions

To fix the missing shadow issue, update your prompt to include specific directives regarding the surface and lighting. Use phrases such as "resting on a wooden table," "casting a soft contact shadow," or "grounded by realistic lighting." Avoid vague terms like "nice background" and instead describe the material of the surface, as different textures reflect light differently. For example, a glossy marble surface will create a different shadow profile than a matte concrete floor.

If you are using an image-to-image workflow, ensure that the input image clearly shows the object in relation to a surface. If the source image is a pure cutout with a transparent background, the AI may struggle to invent a shadow without strong textual guidance. In such cases, adding a description of the intended surface in the prompt is critical.

You can also experiment with negative prompting if the interface allows, explicitly excluding terms like "floating," "ghostly," or "disconnected." However, positive reinforcement of the desired outcome is generally more effective. Be sure to verify that you are using the correct model version for the task. If you are using Nano Banana 2 Lite for a complex scene requiring precise shadow placement, consider switching to the standard Nano Banana 2 to leverage its better handling of multi-element scenes.

Verifying the Results and Next Steps

After applying these changes, regenerate the image and inspect the base of the product closely. Look for a gradual darkening where the object meets the surface. The shadow should not be a hard black line but a soft gradient that fades into the background. If the shadow is still missing, try increasing the specificity of the lighting description, such as "overhead studio lighting casting a defined shadow."

If the issue persists across multiple generations with varied prompts, it may indicate a limitation in the current model's ability to handle that specific combination of transparency and surface texture. In such cases, reviewing the official documentation for the specific model you are using can provide further insights into its strengths and weaknesses. For those looking to explore advanced features or different model capabilities, Try Nano Banana to access the full range of tools available for refining your images.

By systematically adjusting your prompts to emphasize physical grounding and surface interaction, you can effectively eliminate the floating effect and achieve professional-grade results with transparent products.