talk · Tuesday 22 September · 12:03–⁠12:15 · SAL A

Towards Scalable Trait Measurements from Digitized Specimens

Kenzo Milleville · AI for Biodiversity Data

Recording time 3:34:17–3:47:57Open on Vimeo ↗

Summaries and key moments are machine-produced. Check the recording for the speaker’s exact words.

The short versionMatching rulers to an annotated reference set lets specimen images be calibrated to real-world units with under 1% error in 96% of cases.

Overview

What this was about

Kenzo Milleville presented a method to convert pixel measurements on specimen images into metric units by reading the ruler on the sheet. Instead of predicting scale directly, the ruler is detected and normalised, similar rulers are retrieved from an annotated reference set with a CLIP-like similarity model, and a keypoint-matching model transforms the known tick marks onto the new image, requiring in principle only one labelled example per ruler type. The reference set grew to about 2,000 rulers (21,000 annotated points, ~350 institutions), and 96% of predictions now have under 1% error (mean ~0.3%, below the ~0.8% manual annotation error). A proof of concept with Segment Anything 3 measured leaf sizes across taxa and geography. He recommended including ArUco markers or QR codes of known size during digitisation, and noted a proposal to Audiovisual Core to standardise such metadata and the idea of sharing length annotations via DiSSCo.

Why it matters. Normalised measurements are a prerequisite for comparing traits across collections and at global scale from digitised specimens.

Key ideas

In the room

  • Rulers are highly diverse but frequently reused across institutions.
  • Pipeline: object detection, normalisation, similarity retrieval (top 3), keypoint matching, post-processing.
  • Main improvement over last year's Living Data version comes from a larger dataset and renewed models, especially keypoint matching.
  • Robust to lower resolution and partial occlusion; high-contrast popular rulers perform best; simple block rulers worst.
  • Annotation error is roughly constant in pixels regardless of image resolution.
  • No standard yet for storing calibration metadata; proposal submitted on GitHub for Audiovisual Core.
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Notable moments

In their words

Transcript

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Programme abstract

Towards Scalable Trait Measurements from Digitized Specimens

Kenzo Milleville

The increasing digitization of natural history collections creates opportunities for large-scale extraction of quantitative specimen traits. Morphological traits such as specimen shape and size are important for research in ecology and biodiversity. To obtain reliable and comparable traits from images, pixel measurements are converted into metric units using a scale conversion factor (CF), typically calculated by measuring pixel distances between ruler tick marks.

We build upon our previous work on automated ruler detection and scale estimation for herbarium specimens by improving its robustness and scalability. The original approach relied solely on image keypoint matching for CF estimation, which performed well for conventional rulers but was unreliable for simpler ruler types. We extend the original method with a hierarchical framework that first identifies the ruler type and then selects the most appropriate method for CF estimation. These simple rulers, such as lines, blocks, and grids, are processed differently, using a combination of computer vision methods and LLMs.

To evaluate this new approach, our dataset has been expanded beyond herbaria to a broader range of domains, including zoological, entomological, geological, and microscopy images. Furthermore, we show how the estimated CF values can be stored as standardized metadata to support interoperability and how markers can simplify scale estimation in future digitization workflows. Finally, we show how the scale estimation method can be combined with segmentation models to automatically extract specimen traits.

Submitted to the conference programme before the talk, so the talk itself may differ.