Some questions about shark matching/various algorithms

What Wildbook are you working in? Sharkbookl

As all the sharks have transitioned to sharkbook, I’ve got a few questions about spot mapping and matching.

I remember hearing that Hotspotter has been outperforming Groth, so I want to try using that more, but I have a question with regard to cropping the images. I assume when we do the spot mapping, the crop we select while doing that will also be the crop used for Hotspotter, but it wouldn’t utilize the spots we’ve chosen. With the old algorithm on Manta Matcher I know that consistency in how we cropped images could improve matching results. Is this still true of Hotspotter?

The main reason I ask is that the leopard shark spot mapping previously used the pelvic fin as the rear reference point, but now it’s the posterior pectoral, the same as for whale sharks. This has changed how we’re cropping the images as we spot map. So now I’m wondering if it would be useful to go back and recrop older uploads, or if this would be unnecessary.

Thanks!

Hi @AFlam

I assume when we do the spot mapping, the crop we select while doing that will also be the crop used for Hotspotter, but it wouldn’t utilize the spots we’ve chosen.

That is correct.

With the old algorithm on Manta Matcher I know that consistency in how we cropped images could improve matching results. Is this still true of Hotspotter?

Consistency will help, but we don’t have any benchmark of how much. My instinct is that minor and natural variation in cropping will have little impact. The algorithm is pretty tolerant.

The main reason I ask is that the leopard shark spot mapping previously used the pelvic fin as the rear reference point, but now it’s the posterior pectoral, the same as for whale sharks. This has changed how we’re cropping the images as we spot map. So now I’m wondering if it would be useful to go back and recrop older uploads, or if this would be unnecessary.

Great question. I do not recommend going back and reprocessing old imagery as I don’t think it will significantly improve matching due to HotSpotter’s good ability to match varying patterning area.

I am actually hoping that we have time in the future to go to full body matching, which is what we do for most new species with HotSpotter. I would love your feedback, David Robinson’s, and others’ in the community on whether we should switch to full body crops sooner rather than later.

Thanks,
Jason

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Great, thanks.

To switch to full body crops, what would you need from us? Just the majority of our IDs as full-body photos? The majority of our IDs are full-body these days. It’s mostly older shots that wouldn’t have the full-body. We’ve been aiming to get that in our IDs for a while, and more people are using wider angle cameras these days.