Evaluating Sentence Transformers' Understanding of Quasi-Geospatial Concepts from General Text

Core Concepts

Sentence transformers fine-tuned on general question-answering datasets demonstrate some zero-shot ability to associate subjective queries about hiking experiences with synthetically generated route descriptions, but performance is mixed and model-dependent.

Abstract

The study investigates the extent to which sentence transformers, fine-tuned on general (non-geospatial) question-answering datasets, can understand vague, subjective, and complex quasi-geospatial concepts when performing asymmetric semantic search.
The authors:

Use 496,723 user-generated hiking routes across Great Britain and generate textual descriptions for them based on various geospatial attributes.
Employ five sentence transformer models (based on MiniLM, DistilBERT, and MPNet architectures) fine-tuned on MS MARCO and/or a compilation of question-answering datasets.
Test the models with 20 queries resembling questions about hiking experiences, and analyze the relevance of ranked route descriptions.
The results are mixed:

The models perform well on simple queries like "a walk by the seaside" or "an urban walk", associating them with routes having longer stretches along the coast or going through urban areas.
For more complex queries targeting easier or harder hiking experiences, the models show varying degrees of success in ranking routes based on length, elevation gain, and steepness.
Even models fine-tuned on the same dataset can disagree on which routes can be completed in under an hour.
The models struggle to associate "long" and "very long" walks with higher kilometer values, and often rank shorter and flatter walks as more suitable for "someone seeking greater challenges".
The authors suggest future work should explore a more systematic approach to evaluating sentence transformers and other language models for geospatial understanding, focusing on model architecture, fine-tuning datasets, geospatial description generation, and evaluation methods.

Stats

This is a 22 km walk that begins in Rampart Head, Cumberland and ends in Little Caldew, Cumberland. Total elevation gain is 222 metres, and elevation grade is 1.0.
About 6 percent of the walk is in a wooded area, about 9 percent of the walk goes through an urban area, about 7 percent of the walk is within green space, about 18 percent of the walk is along the coast, about twenty-seven percent of the walk is alongside a body of water.
This is a nineteen km walk that begins in Millbrook, Caerffili - Caerphilly and ends in Ynysfro Reservoirs, Casnewydd - Newport. Total elevation gain is seven hundred and twenty-four metres, and elevation grade is 3.7.
The walk is predominantly downhill. About seventeen percent of the walk is in a wooded area, about forty-five percent of the walk goes through an urban area, about eight percent of the walk is within green space, about 17 percent of the walk is alongside a body of water.

Quotes

"This is a circular, 12 km walk that begins and ends in Tarrant Gunville, Dorset. Total elevation gain is one hundred and ninety-one metres, and elevation grade is 1.6."
"This is a 6 km walk that begins in Pebbly Hill, Cotswold, Gloucestershire and ends in Stow-on-the-Wold, Cotswold, Gloucestershire. Total elevation gain is 215 metres, and elevation grade is 3.5. The walk is predominantly uphill."

Key Insights Distilled From

Do Sentence Transformers Learn Quasi-Geospatial Concepts from General Text?

by Ilya Ilyanko... at arxiv.org 04-08-2024

https://arxiv.org/pdf/2404.04169.pdf

Deeper Inquiries

How could the authors incorporate user feedback or crowdsourced labels to better evaluate the relevance of route descriptions to hiking queries?

To enhance the evaluation of route descriptions' relevance to hiking queries, the authors could implement a feedback loop mechanism where users provide feedback on the accuracy and usefulness of the recommendations. This feedback could include ratings, comments, or explicit labels indicating whether the suggested routes matched their expectations. By collecting this user-generated data, the authors can create a labeled dataset that can be used to train and fine-tune the sentence transformers further. Crowdsourcing platforms could also be utilized to gather a larger and more diverse set of labels, ensuring a comprehensive evaluation of the model's performance across different user preferences and hiking experiences. Additionally, incorporating user feedback can help in iteratively improving the model's understanding of quasi-geospatial concepts related to hiking, leading to more accurate and personalized route recommendations.

What biases might be present in the user-generated route data, and how could the authors account for them in their analysis?

User-generated route data may exhibit biases based on the demographics, preferences, and behaviors of the individuals creating the routes. Biases could arise from factors such as geographic location, accessibility to certain areas, popularity of specific trails, and personal interests of the users. To address these biases in their analysis, the authors could implement several strategies:

Diversity Sampling: Ensure that the dataset includes a diverse range of routes from various regions, terrains, and difficulty levels to mitigate geographic biases.
Anonymization: Remove any identifying information from the routes to prevent biases related to specific users or groups.
Balanced Representation: Strive to have an equal representation of different types of routes (e.g., coastal, woodland, urban) to avoid over-representation of certain categories.
Bias Detection: Use statistical methods to identify and quantify biases in the dataset, allowing for targeted corrections or adjustments during the analysis.
Validation: Validate the results against external sources or expert opinions to cross-check for any biases that might affect the model's performance. By acknowledging and addressing these biases, the authors can ensure a more robust and unbiased analysis of the user-generated route data.

Could the authors explore incorporating additional geospatial features, such as terrain type or points of interest, to improve the sentence transformers' understanding of hiking experiences?

Incorporating additional geospatial features, such as terrain type and points of interest, can significantly enhance the sentence transformers' understanding of hiking experiences and improve the relevance of route recommendations. By including information about terrain characteristics (e.g., mountainous, flat, rocky) and points of interest along the routes (e.g., waterfalls, viewpoints, historical sites), the model can better capture the unique aspects of each hiking experience. This enriched dataset can provide more context and specificity to the route descriptions, enabling the sentence transformers to make more informed associations between user queries and route attributes.
To implement this enhancement, the authors could:

Feature Engineering: Extract and encode geospatial features like terrain type, elevation changes, vegetation cover, and notable landmarks into the route descriptions.
Data Augmentation: Introduce synthetic data or augmented descriptions that include diverse geospatial elements to expand the model's training data.
Multi-Modal Learning: Explore multi-modal approaches that combine textual descriptions with geospatial data (e.g., maps, images) to create a richer representation of hiking routes.
Fine-Tuning: Fine-tune the sentence transformers on a dataset that includes these additional geospatial features to improve the model's understanding of hiking-related concepts and preferences.
By incorporating terrain type and points of interest into the analysis, the authors can offer more personalized and contextually relevant hiking recommendations, catering to a broader range of user preferences and interests.