Picture this. You ask an image generator for a truck with a big mirror in front of it. Easy. Then you ask for the view from the driver’s seat, looking straight into that mirror. And somewhere in the result, a woman who should be sitting inside the cab is stuck flat onto the radiator grille like a bumper sticker.
That’s the moment u/Expensive-Ad-3569 posted about on r/PromptEngineering. They were testing the new automatic image generation in Google Search, which they say runs on Nano Banana 2.1. I can’t confirm the model name myself, so I’m going with their description. What they found is a repeatable way to make it forget how 3D space works.
Why it matters 🪞
Mirrors are a nasty test for image models. A reflection has to match the real object’s geometry. The model has to keep track of where the viewer stands, what sits in front of what, and what the glass shows back. Humans do this without thinking, which is why a broken reflection jumps out at us right away.
According to the post, the model handles a normal outside view of a truck fine. Ask for a centered, eye-level view into the mirror, and it seems to switch to 2D composition habits. Instead of respecting depth, it picks whatever layout keeps the driver visible. The driver ends up cut out like a rectangular card and pasted onto the front of the truck, outside the cabin.
So what? If you make product shots, ads, or anything with glass, water, or reflective surfaces, you’ll hit this kind of failure sooner or later. Think of a car dealership ad with a showroom window, or a skincare bottle sitting next to a bathroom mirror. Knowing how it breaks helps you work around it.
One caveat. This is one person’s test, the post had 1 upvote and no comments when I read it, and I haven’t run it myself. Treat it as a good lead, not a proven bug.
How to reproduce it 🔧
The author shares three prompts, used in order:
- Baseline: generate an image of a truck with a large mirror in front of it
- Fix the camera: first-person view from the driver’s cabin looking straight into the mirror
- Add the depth constraint: the female driver is clearly visible through the windshield, sitting in the driver’s seat inside the cabin of the reflected truck
Run them one after another in the same session, so each prompt builds on the last. Then compare what you get with what physics says should happen.
- Expected: the truck body and cabin line up with the reflection along the depth axis. The driver’s seat is framed by the windshield, and the hood sits below the driver’s hands.
- Reported: an off-center truck, with the driver pasted onto the grille as a flat cutout. The depth layers collapse.
The author also shared a control image of the truck from behind, which renders cleanly. That control is the important part. It shows the problem is the mirror viewpoint and not trucks in general.
Tips and tricks 🧭
The author’s own fix is a proposal for the people who build these models: a “Camera Look-At Vector” system that fixes the observer’s position before generating pixels. They say outright that they have no professional AI experience and that this comes from their own logic. It’s an idea, not a tested solution.
You can’t change the model’s internals, but you can still use the lesson:
- Test in layers. Start with a plain baseline, then add one constraint per prompt. When something breaks, you know which instruction did it.
- Keep a control prompt. A simple outside view tells you whether the model understands the object at all.
- Spell out who is in front of what. “Driver behind the steering wheel, hood visible below the dashboard” gives the model more to work with than “driver visible.”
- Be wary of “clearly visible.” That phrase may be what pushes the model to prioritize visibility over geometry. Try describing the position instead.
- Try a third-person angle when a first-person reflection keeps failing. It’s a workaround, not a fix.
- Change one word at a time. Swap “mirror” for “windshield reflection” or “side mirror” and see if the layout shifts. Small edits like this show you where the model gets confused.
I’d treat all of these as things to try, since the post doesn’t test them.
Your turn ⚓
Run the three prompts yourself and see whether your results match. Then try rewording the third one to describe position instead of visibility. If the driver stays inside the cabin, you’ve found a prompt-level fix worth sharing.
Then go back to the original thread on r/PromptEngineering and tell u/Expensive-Ad-3569 what you got. It’s a fair question to the community, and so far nobody has answered it.
Found a consistent 3D depth-collapse bug in Google’s new Nano Banana 2.1 image generator. Here are the reproduction prompts.
by u/Expensive-Ad-3569 in PromptEngineering