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splits:
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- config_name: Joint
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download_size: 988185534
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- config_name: Spatial_Reasoning
features:
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splits:
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num_examples: 400
download_size: 3518112486
dataset_size: 3529099222
configs:
- config_name: Application
data_files:
- split: train
path: Application/train-*
- split: test
path: Application/test-*
- config_name: ENC_Perception
data_files:
- split: train
path: ENC_Perception/train-*
- split: test
path: ENC_Perception/test-*
default: true
- config_name: Joint
data_files:
- split: train
path: Joint/train-*
- split: test
path: Joint/test-*
- config_name: Spatial_Reasoning
data_files:
- split: train
path: Spatial_Reasoning/train-*
- split: test
path: Spatial_Reasoning/test-*
- split: test-balanced
path: Spatial_Reasoning/test-balanced-*
language:
- en
ENC-QA
ENC-QA evaluates vision-language model (VLM) understanding of Electronic Navigational Charts (ENCs). The benchmark measures whether models can interpret standardized nautical-chart symbols and text, reason about spatial relationships among chart features, combine ENC perception with spatial reasoning, and make navigation-relevant judgments from rendered ENC imagery.
ENC-QA is created from National Oceanic and Atmospheric Administration (NOAA) ENCs encoded using the IHO S-57 standard and rendered using OpenCPN. The benchmark contains approximately 56,000 questions derived from 6,835 NOAA ENCs.
The benchmark consists of four tasks in increasing complexity:
- ENC Perception: recognize and interpret symbols, objects, text, and symbol-text associations visible in an ENC render.
- Spatial Reasoning: reason about topology, distance, and direction between chart features.
- Joint Perception and Spatial Reasoning: identify relevant chart features and use them jointly to answer spatial questions.
- Application: synthesize perceptual and spatial information into navigation-relevant judgments.
Data organization
Each benchmark example is represented by a row in a questions.csv file. The row contains the question, answer, image path, chart-cell identifier, task labels, and structured metadata used to generate or verify the example.
A task directory follows the general pattern:
ENC-QA/
├── data/
│ ├── ENC_Perception/
│ │ ├── isolated_symbol_recognition/
│ │ │ ├── questions.csv
│ │ │ └── images/
│ │ ├── incontext_symbol_recognition/
│ │ │ ├── questions.csv
│ │ │ └── images/
│ │ ├── symbol_text_association/
│ │ │ ├── questions.csv
│ │ │ └── images/
│ │ └── ...
│ ├── Spatial_Reasoning/
│ │ └── ...
│ ├── Joint/
│ │ └── ...
│ └── Application/
│ └── ...
└── README.md
Within each task directory, image paths in questions.csv are stored relative to the directory containing the CSV. For example:
images/US1EEZ1M_encperception_756619221_lat15.060136_lon145.793954_labeled.png
The CSV files are the authoritative definition of the examples included in each benchmark task.
Task hierarchy
ENC-QA uses three fields to identify where an example belongs in the benchmark:
task— broad benchmark level.subtask— specific task within that level.q_type— fine-grained question or portrayal type.
For example, an in-context symbol-recognition example can use:
task = enc_perception
subtask = incontext_symbol_recognition
q_type = ADMARE/ADMARE
A spatial-reasoning example can use:
task = spatial_reasoning
subtask = topological
q_type = within
q_type should be treated as the fine-grained category produced by the question-generation pipeline. Its format depends on the task. For some ENC-perception questions it can contain an object class and portrayal separated by /, while for spatial-reasoning questions it can directly identify the tested relation.
Task definitions
ENC Perception
ENC Perception evaluates whether a model can correctly identify and interpret individual chart elements.
The task includes:
- Isolated Symbol Recognition: identify an ENC object or symbol from an isolated or localized visual example.
- In-Context Symbol Recognition: identify an ENC object within a rendered chart scene.
- Symbol-Text Association: associate a chart symbol or feature with the corresponding visible text or label.
For example:
task = enc_perception
subtask = incontext_symbol_recognition
In-context symbol-recognition questions ask the model to identify the object or feature represented by a highlighted point symbol, line, or area.
Spatial Reasoning
Spatial Reasoning evaluates whether a model can reason about relationships between multiple chart features while minimizing dependence on ENC-specific semantic knowledge.
The task includes:
- Topology
- within
- touch
- overlap
- cross
- equal
- Distance
- quantitative distance
- qualitative distance
- Direction
- cardinal / 8-direction reasoning
- exact bearing reasoning
To isolate spatial reasoning capability, the relevant objects or features are referred to using neutral visual identifiers such as red and blue, rather than by their ENC object classes. Questions can require true/false answers, counts, numeric distances, directional labels, or bearings grounded in the rendered chart.
Joint Perception and Spatial Reasoning
Joint tasks require both visual grounding and spatial reasoning. A model must identify the relevant ENC features and then reason over their spatial relationship.
These tasks are designed to test whether a model can successfully combine the ENC-perception and spatial-reasoning capabilities that are evaluated separately in the lower-level tasks.
Application
Application tasks evaluate whether a model can synthesize multiple ENC cues into a navigation-relevant judgment. These questions can require combining navigational aids, restricted areas, depth information, hazards, traffic routes, shoreline features, object attributes, and spatial relationships.
Current Application subdivisions include:
- Travel Direction: determine the intended or appropriate direction of travel from information visible on the chart.
- Travel Permission: determine whether travel or entry is permitted in the relevant chart area. This includes questions about whether travel is permitted and whether entry into a particular area is restricted.
- Change Criticality: identify changes between two versions of a chart and determine whether those changes are critical to navigational safety.
Application examples may rely on both visible chart evidence and ENC feature attributes. The visible metadata field indicates whether the information needed to recover the answer is visually available in the rendered image.
CSV schema
The current schema uses the following 15 columns when both natural-language and S-57-coded answers are included:
| Column | Description |
|---|---|
id |
Unique string identifier for the example. In ENC-perception data, the identifier can include the ENC cell, task, a generated numeric token, and image-center latitude/longitude. |
task |
Broad benchmark task, e.g. enc_perception. |
subtask |
Specific benchmark subtask, e.g. incontext_symbol_recognition. |
q_type |
Fine-grained question or portrayal category, e.g. ADMARE/ADMARE, POSGEN/POSGEN04, MAGVAR/MAGVAR51, or within. |
question |
Natural-language prompt given to the model. |
answer |
Natural-language ground-truth answer. |
answer_alt |
Alternate ground-truth answer using the S-57 object code, portrayal code, abbreviation, or other task-specific coded representation when applicable. |
referrable |
Boolean metadata flag produced by the question-generation pipeline indicating whether the target is marked as referrable. |
visible |
Boolean indicating whether the information required for the answer is considered visible in the rendered image. |
image |
Relative path to the primary image used for the question. |
image_alt |
Relative path to a paired alternate rendering when available. For in-context recognition, this is the corresponding scene without the target highlight/annotation. |
cell |
NOAA ENC cell identifier, e.g. US1EEZ1M. |
target_layer |
S-57/ENC layer containing the target source feature, e.g. ADMARE, COALNE, or LNDELV. This is not necessarily identical to the final portrayal label or answer. |
img_center |
Image-center coordinate stored as [longitude, latitude]. |
feature |
JSON-encoded list containing structured metadata for the source feature or features used to generate the question. |
Not every task necessarily requires every optional field. Fields such as answer_alt, image_alt, target_layer, img_center, or feature may be empty when they are not applicable to a particular task.
Example row
A simplified in-context symbol-recognition example is:
id:
US1EEZ1M_encperception_756619221_lat15.060136_lon145.793954
task:
enc_perception
subtask:
incontext_symbol_recognition
q_type:
ADMARE/ADMARE
question:
The image displays a symbol used to represent ENC data on an ECDIS.
What type of object or feature does the highlighted area portray?
Give the final answer in <answer> </answer> tags.
answer:
Administration Area (Named)
answer_alt:
ADMARE
visible:
True
image:
images/US1EEZ1M_encperception_756619221_lat15.060136_lon145.793954_labeled.png
image_alt:
images/US1EEZ1M_encperception_756619221_lat15.060136_lon145.793954.png
cell:
US1EEZ1M
target_layer:
ADMARE
img_center:
[145.79395375541344, 15.06013575]
The prompt's <answer> </answer> instruction specifies the expected model-output format. The CSV ground-truth fields themselves store the answer text without requiring the tags.
For example, either of the following can be formatted for model evaluation:
<answer>Administration Area (Named)</answer>
or, when evaluating against the coded alternative:
<answer>ADMARE</answer>
Feature metadata
The feature column stores a JSON-encoded list containing metadata for the source feature or features associated with an example.
Common fields include:
| Field | Description |
|---|---|
layer |
ENC layer associated with the feature. |
geometry_type |
Geometry class, such as point, line, or polygon. |
geometry |
Serialized geometry representation for the source feature. |
fid |
Feature identifier used by the source data-processing pipeline. |
rcid |
S-57 record identifier. |
object_name |
Human-readable object-class name when available. |
target_label |
Target label produced for the task. |
target_label_source |
Generator metadata describing how target_label was selected. |
portrayal_name |
Portrayal or symbol identifier associated with the target. |
attributes |
Serialized dictionary containing source S-57 attributes. |
For example:
[
{
"layer": "ADMARE",
"geometry_type": "polygon",
"fid": 141,
"rcid": 142,
"object_name": "Administration Area (Named)",
"target_label": "ADMARE",
"target_label_source": "object_class_for_polygon_task",
"portrayal_name": "ADMARE",
"geometry": "...",
"attributes": "..."
}
]
geometry and attributes may themselves be stored as serialized strings rather than recursively expanded JSON objects.
Primary and alternate images
Some ENC-QA tasks contain two image fields:
image— the primary image associated with the question.image_alt— a paired alternate rendering of the same scene.
For in-context symbol recognition, filenames follow the convention:
image:
images/{id}_labeled.png
image_alt:
images/{id}.png
The primary image contains the target highlight or annotation used by the question. The alternate image preserves the corresponding chart scene without that target annotation. It may still contain normal chart labels and other OpenCPN-rendered content.
Identifier and coordinate convention
For ENC-perception examples, identifiers can follow the pattern:
{cell}_encperception_{generated_id}_lat{latitude}_lon{longitude}
For example:
US1EEZ1M_encperception_756619221_lat15.060136_lon145.793954
The corresponding img_center is stored in GIS coordinate order:
[longitude, latitude]
For the example above:
[145.79395375541344, 15.06013575]
Do not interpret img_center as [latitude, longitude].
Dataset statistics
Final counts should be filled in after dataset generation, filtering, deduplication, and split assignment are complete.
| Configuration | Total |
|---|---|
| ENC Perception | TODO |
| Isolated Symbol Recognition | TODO |
| In-Context Symbol Recognition | TODO |
| Symbol-Text Association | TODO |
| Spatial Reasoning | TODO |
| Topological | TODO |
| Distance | TODO |
| Direction | TODO |
| Joint Perception and Spatial Reasoning | TODO |
| Application | TODO |
| Travel Direction | TODO |
| Travel Permission | TODO |
| Change Criticality | TODO |
| Total | ~56k |
Data sources
NOAA Electronic Navigational Charts
ENC-QA is derived from NOAA Electronic Navigational Charts. ENCs are vector nautical charts encoded using the IHO S-57 data model and contain navigational objects, attributes, geometry, and chart metadata.
Data checkpoint: June 1, 2026.
Chart rendering
ENC source data are converted into rendered chart imagery for the visual benchmark using OpenCPN. Structured ENC information is used to identify source features, attributes, and geometric relationships, while the rendered chart is provided as the visual model input.
Example usage
Reading the CSV
from pathlib import Path
import pandas as pd
task_root = Path(
"/path/to/ENC-QA/data/ENC_Perception/incontext_symbol_recognition"
)
questions = pd.read_csv(task_root / "questions.csv")
row = questions.iloc[0]
image_path = task_root / row["image"]
image_alt_path = (
task_root / row["image_alt"]
if pd.notna(row.get("image_alt"))
else None
)
print(row["id"])
print(row["task"])
print(row["subtask"])
print(row["q_type"])
print(row["question"])
print(row["answer"])
print(row.get("answer_alt"))
print(image_path)
print(image_alt_path)