lance-format/eurosat-lance

EuroSAT (Lance Format)

A Lance-formatted version of EuroSAT, the canonical Sentinel-2 RGB land-cover benchmark, sourced from blanchon/EuroSAT_RGB. Each row is a single 64×64 RGB tile with its integer class id, the human-readable class name, and a cosine-normalized OpenCLIP image embedding — all stored inline and available directly from the Hub at hf://datasets/lance-format/eurosat-lance/data.

Key features

• Inline JPEG bytes in the image column — no sidecar TIF folders, no per-class subdirectories.
• Pre-computed OpenCLIP image embeddings (image_emb, ViT-B/32, 512-dim, cosine-normalized) with a bundled IVF_PQ index for similarity search.
• Both label representations — integer label (0-9) and string label_name — with scalar indices on both for fast class filters.
• One columnar dataset — scan labels and embeddings cheaply, fetch tile bytes only for the rows you actually need.

Splits

Split	Rows	Notes
train.lance	16,200	Training split
validation.lance	5,400	Validation split
test.lance	5,400	Held-out test split

Schema

Column	Type	Notes
id	int64	Row index within the split (natural join key)
image	large_binary	Inline JPEG bytes (64×64 RGB Sentinel-2 tile)
label	int32	Class id (0-9)
label_name	string	One of Annual_Crop, Forest, Herbaceous_Vegetation, Highway, Industrial_Buildings, Pasture, Permanent_Crop, Residential_Buildings, River, SeaLake
image_emb	fixed_size_list<float32, 512>	OpenCLIP ViT-B-32 image embedding (cosine-normalized)

Pre-built indices

• IVF_PQ on image_emb — vector similarity search (cosine)
• BTREE on label — fast equality / range filters by class id
• BITMAP on label_name — fast set-membership filters by class name

Why Lance?

1. Blazing Fast Random Access: Optimized for fetching scattered rows, making it ideal for random sampling, real-time ML serving, and interactive applications without performance degradation.
2. Native Multimodal Support: Store text, embeddings, and other data types together in a single file. Large binary objects are loaded lazily, and vectors are optimized for fast similarity search.
3. Native Index Support: Lance comes with fast, on-disk, scalable vector and FTS indexes that sit right alongside the dataset on the Hub, so you can share not only your data but also your embeddings and indexes without your users needing to recompute them.
4. Efficient Data Evolution: Add new columns and backfill data without rewriting the entire dataset. This is perfect for evolving ML features, adding new embeddings, or introducing moderation tags over time.
5. Versatile Querying: Supports combining vector similarity search, full-text search, and SQL-style filtering in a single query, accelerated by on-disk indexes.
6. Data Versioning: Every mutation commits a new version; previous versions remain intact on disk. Tags pin a snapshot by name, so retrieval systems and training runs can reproduce against an exact slice of history.

Load with datasets.load_dataset

You can load Lance datasets via the standard HuggingFace datasets interface, suitable when your pipeline already speaks Dataset / IterableDataset or you want a quick streaming sample without installing anything Lance-specific.

import datasets

hf_ds = datasets.load_dataset("lance-format/eurosat-lance", split="train", streaming=True)
for row in hf_ds.take(3):
    print(row["label_name"])

Load with LanceDB

LanceDB is the embedded retrieval library built on top of the Lance format (docs), and is the interface most users interact with. It wraps the dataset as a queryable table with search and filter builders, and is the entry point used by the Search, Curate, Evolve, Train, Versioning, and Materialize-a-subset sections below.

import lancedb

db = lancedb.connect("hf://datasets/lance-format/eurosat-lance/data")
tbl = db.open_table("train")
print(len(tbl))

Load with Lance

pylance is the Python binding for the Lance format and works directly with the format's lower-level APIs. Reach for it when you want to inspect or operate on dataset internals — schema, scanner, fragments, and the list of pre-built indices.

import lance

ds = lance.dataset("hf://datasets/lance-format/eurosat-lance/data/train.lance")
print(ds.count_rows(), ds.schema.names)
print(ds.list_indices())

Tip — for production use, download locally first. Streaming from the Hub works for exploration, but heavy random access and ANN search are far faster against a local copy:

hf download lance-format/eurosat-lance --repo-type dataset --local-dir ./eurosat-lance

Then point Lance or LanceDB at ./eurosat-lance/data.

Search

The bundled IVF_PQ index on image_emb makes visually-similar-tile retrieval a single call. In production you would encode a query tile through the same OpenCLIP ViT-B-32 model used at ingest (cosine-normalized) and pass the resulting 512-d vector to tbl.search(...). The example below uses the embedding already stored in row 42 as a runnable stand-in, so the snippet works without any model loaded.

import lancedb

db = lancedb.connect("hf://datasets/lance-format/eurosat-lance/data")
tbl = db.open_table("train")

seed = (
    tbl.search()
    .select(["image_emb", "label_name"])
    .limit(1)
    .offset(42)
    .to_list()[0]
)

hits = (
    tbl.search(seed["image_emb"])
    .metric("cosine")
    .select(["id", "label_name"])
    .limit(10)
    .to_list()
)
print(f"reference tile class: {seed['label_name']}")
for r in hits:
    print(f"  id={r['id']:>6}  {r['label_name']}")

Because the embeddings are cosine-normalized at ingest, metric="cosine") is the right choice and the first hit will typically be the seed tile itself — a useful sanity check. Tune nprobes and refine_factor to trade recall against latency for your workload.

Curate

A typical curation pass for a land-cover classification or retrieval study narrows the dataset to a single class and then retrieves the visually closest tiles to a seed. Lance evaluates the vector search and the metadata filter inside a single query, so the candidate set comes back already filtered. The example below pulls the 500 forest tiles most similar to a chosen seed; the bounded .limit(500) keeps the output small enough to inspect or hand off.

import lancedb

db = lancedb.connect("hf://datasets/lance-format/eurosat-lance/data")
tbl = db.open_table("train")

seed = (
    tbl.search()
    .select(["image_emb"])
    .limit(1)
    .offset(0)
    .to_list()[0]
)

candidates = (
    tbl.search(seed["image_emb"])
    .where("label_name = 'Forest'", prefilter=True)
    .select(["id", "label", "label_name"])
    .limit(500)
    .to_list()
)
print(f"{len(candidates)} Forest candidates")

The result is a plain list of dictionaries, ready to inspect, persist as a manifest of row ids, or feed into the Evolve and Train workflows below. The image column is never read, so the network traffic for a 500-row candidate scan is dominated by the small metadata payload rather than JPEG bytes.

Evolve

Lance stores each column independently, so a new column can be appended without rewriting the existing data. The lightest form is a SQL expression: derive the new column from columns that already exist, and Lance computes it once and persists it. The example below adds a coarse is_urban flag that captures whether a tile belongs to one of the built-environment classes, useful as a direct predicate in later where clauses without re-evaluating the class set on every query.

Note: Mutations require a local copy of the dataset, since the Hub mount is read-only. See the Materialize-a-subset section at the end of this card for a streaming pattern that downloads only the rows and columns you need, or use hf download to pull the full corpus first.

import lancedb

db = lancedb.connect("./eurosat-lance/data")  # local copy required for writes
tbl = db.open_table("train")

tbl.add_columns({
    "is_urban": "label_name IN ('Highway', 'Industrial_Buildings', 'Residential_Buildings')",
})

If the values you want to attach already live in another table (a coarse climate label per class, an external aesthetic score, model predictions from a separate eval), merge them in by joining on label_name:

import pyarrow as pa

climate = pa.table({
    "label_name": pa.array(["Forest", "Pasture", "SeaLake", "River"]),
    "climate_zone": pa.array(["temperate", "temperate", "marine", "freshwater"]),
})
tbl.merge(climate, on="label_name")

The original columns and indices are untouched, so existing code that does not reference the new columns continues to work unchanged. New columns become visible to every reader as soon as the operation commits. For column values that require a Python computation (e.g., running an alternative remote-sensing model over the tile bytes), Lance provides a batch-UDF API in the underlying library — see the Lance data evolution docs for that pattern.

Train

Projection lets a training loop read only the columns each step actually needs. LanceDB tables expose this through Permutation.identity(tbl).select_columns([...]), which plugs straight into the standard torch.utils.data.DataLoader so prefetching, shuffling, and batching behave as in any PyTorch pipeline. Columns added in the Evolve section above cost nothing per batch until they are explicitly projected.

import lancedb
from lancedb.permutation import Permutation
from torch.utils.data import DataLoader

db = lancedb.connect("hf://datasets/lance-format/eurosat-lance/data")
tbl = db.open_table("train")

train_ds = Permutation.identity(tbl).select_columns(["image", "label"])
loader = DataLoader(train_ds, batch_size=128, shuffle=True, num_workers=4)

for batch in loader:
    # batch carries only the projected columns; image_emb stays on disk.
    # decode the JPEG bytes, forward through a CNN or ViT, cross-entropy loss...
    ...

Switching feature sets is a configuration change: passing ["image_emb", "label"] to select_columns(...) on the next run skips JPEG decoding entirely and reads only the cached 512-d vectors, which is the right shape for training a linear probe or a lightweight classifier head on top of frozen CLIP features.

Versioning

Every mutation to a Lance dataset, whether it adds a column, merges labels, or builds an index, commits a new version. Previous versions remain intact on disk. You can list versions and inspect the history directly from the Hub copy; creating new tags requires a local copy since tags are writes.

import lancedb

db = lancedb.connect("hf://datasets/lance-format/eurosat-lance/data")
tbl = db.open_table("train")

print("Current version:", tbl.version)
print("History:", tbl.list_versions())
print("Tags:", tbl.tags.list())

Once you have a local copy, tag a version for reproducibility:

local_db = lancedb.connect("./eurosat-lance/data")
local_tbl = local_db.open_table("train")
local_tbl.tags.create("clip-vitb32-v1", local_tbl.version)

A tagged version can be opened by name, or any version reopened by its number, against either the Hub copy or a local one:

tbl_v1 = db.open_table("train", version="clip-vitb32-v1")
tbl_v5 = db.open_table("train", version=5)

Pinning supports two workflows. A retrieval system locked to clip-vitb32-v1 keeps returning stable results while the dataset evolves in parallel; newly added columns or labels do not change what the tag resolves to. A training experiment pinned to the same tag can be rerun later against the exact same tiles, so changes in metrics reflect model changes rather than data drift. Neither workflow needs shadow copies or external manifest tracking.

Materialize a subset

Reads from the Hub are lazy, so exploratory queries only transfer the columns and row groups they touch. Mutating operations (Evolve, tag creation) need a writable backing store, and a training loop benefits from a local copy with fast random access. Both can be served by a subset of the dataset rather than the full split. The pattern is to stream a filtered query through .to_batches() into a new local table; only the projected columns and matching row groups cross the wire, and the bytes never fully materialize in Python memory.

import lancedb

remote_db = lancedb.connect("hf://datasets/lance-format/eurosat-lance/data")
remote_tbl = remote_db.open_table("train")

batches = (
    remote_tbl.search()
    .where("label_name IN ('Forest', 'River', 'SeaLake')")
    .select(["id", "image", "label", "label_name", "image_emb"])
    .to_batches()
)

local_db = lancedb.connect("./eurosat-natural-subset")
local_db.create_table("train", batches)

The resulting ./eurosat-natural-subset is a first-class LanceDB database. Every snippet in the Evolve, Train, and Versioning sections above works against it by swapping hf://datasets/lance-format/eurosat-lance/data for ./eurosat-natural-subset.

Source & license

Converted from blanchon/EuroSAT_RGB. EuroSAT is released under the MIT license by Helber et al. The underlying Sentinel-2 imagery is © European Space Agency, made available under the Copernicus open data policy.

Citation

@inproceedings{helber2019eurosat,
  title={EuroSAT: A novel dataset and deep learning benchmark for land use and land cover classification},
  author={Helber, Patrick and Bischke, Benjamin and Dengel, Andreas and Borth, Damian},
  journal={IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing},
  year={2019}
}