feat(alerts): display detection crop overlay on main image

[MateoLostanlen]

Why

Make faster decisions on small fires from afar. The crop gives reviewers a tight, zoomed-in view of the smoke so they can confirm or dismiss without waiting on the full frame.

Companion PRs:

• pyro-engine: send 224x224 detection crop alongside full frame pyro-engine#359
• pyro-api: feat(detections): accept optional crop image for faster smoke checks pyro-api#575

Demo: https://www.loom.com/share/0f5a3c5310044779abf3bb9dcdbc02ec

Note on the demo: the source images are already compressed HD frames, so the actual resolution benefit of the crop isn't really visible in the video. On real raw frames the close-up will be noticeably sharper.

What changes

• Surface the new optional crop_url returned by GET /sequences/{id}/detections (with with_crop=true) in the detection schema.
• Render the crop as a small (~150px) thumbnail pinned to a top corner of the detection viewer, flipping between top-left and top-right based on the bbox center so it never sits on the smoke.
• Add a toggle button next to the existing bbox toggle so reviewers can hide the close-up. The overlay is automatically skipped for older detections without a crop.
• Add buttonDisplayCrop / buttonHideCrop labels in en/fr/es/de (close-up / gros plan / primer plano / Nahaufnahme).

How to test

Run against the dev env with the engine and api PR branches. Heads-up: the current engine PR loops the same image, which makes the demo less convincing. For testing prefer the send_detection_crop_changing_images branch on pyro-engine, which is the same PR plus image rotation. A separate PR will fold that change into engine soon.

Note

This is a first proposal, fully open to discussion on both design and implementation. Feel free to commit directly on this branch if needed.

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Project	Deployment	Actions	Updated (UTC)
new-pyro-platform	Ready	Preview, Comment	May 1, 2026 5:20am

[MateoLostanlen]

I have a few questions to discuss together.
The crop moves from right to left depending on the detection position, which is good, but it hides the little window that shows us where we're zooming. How do we handle this, do we shift the crop, or maybe the crop disappears as soon as we zoom in?
What window size should we use? 150 here, the base image is 224x224.
The name, we say "crop" in English normally, I'm not really sure how to translate it

[fe51]

Hi Mateo, thanks for making a first proposition to #203 !

At this stage of the discussion, provided the crop dimensions remain 224×224, I will try to include the full crop !

Now, as discussed and pointed out in your comment, the crop image must not alter the "map zoom" (At least we need to avoid it)

What about a display that’s always at the bottom right if the light is mainly in the left-hand area (the centre of the bounding boxes of the sequences? Or just the first one?), and vice versa?

So, when might this approach cause problems?
If a bounding box is so wide that, even though it is mainly on one side, it overlaps onto the other side, and the bounding box and the crop area overlap?
On the one hand, this is a situation where we would need to count the number of occurrences; on the other hand, let us remember that the crop area is not displayed by default at this stage (and if it were, one would simply need to click to hide it).