[Paper Review] Occlusion-Free Conformal Lensing for Spatiotemporal Visualization in 3D Urban Analytics

Roberta Mota, Julio Henrique Sales Lima Silva+4 more|arXiv (Cornell University)|Feb 3, 2026

3D Modeling in Geospatial Applications0 citations

TL;DR

The paper presents an immersive lens visualization that uses a view-dependent cutaway and conformal mapping to embed time-series data on building facades, reducing occlusion and clutter in 3D urban analytics; a controlled study shows improved task accuracy and faster completion with higher user confidence.

ABSTRACT

The visualization of temporal data on urban buildings, such as shadows, noise, and solar potential, plays a critical role in the analysis of dynamic urban phenomena. However, in dense and geographically constrained 3D urban environments, visual representations of time-varying building data often suffer from occlusion and visual clutter. To address these two challenges, we introduce an immersive lens visualization that integrates a view-dependent cutaway de-occlusion technique and a temporal display derived from a conformal mapping algorithm. The mapping process first partitions irregular building footprints into smaller, sufficiently regular subregions that serve as structural primitives. These subregions are then seamlessly recombined to form a conformal, layered layout for our temporal lens visualization. The view-responsive cutaway is inspired by traditional architectural illustrations, preserving the overall layout of the building and its surroundings to maintain users' sense of spatial orientation. This lens design enables the occlusion-free embedding of shape-adaptive temporal displays across building facades on demand, supporting rapid time-space association for the discovery, access and interpretation of spatiotemporal urban patterns. Guided by domain and design goals, we outline the rationale behind the lens visual and interaction design choices, such as the encoding of time progression and temporal values in the conforming lens image. A user study compares our approach against conventional juxtaposition and x-ray spatiotemporal designs. Results validate the usage and utility of our lens, showing that it improves task accuracy and completion time, reduces navigation effort, and increases user confidence. From these findings, we distill design recommendations and promising directions for future research on spatially-embedded lenses in 3D visualization and urban analytics.

Motivation & Objective

• Mitigate visual clutter and self-occlusion when visualizing time-varying building data in dense 3D urban scenes.
• Develop a conformal mapping-based layout that adapts irregular building footprints into structured, layered ribbons for temporal display.
• Integrate an immersive, lens-based visualization with view-dependent de-occlusion to preserve spatial orientation.
• Evaluate the visualization against conventional designs to determine gains in accuracy, speed, and perceived usability.
• Provide design recommendations and identify future research directions for spatially-embedded lenses in urban analytics.

Proposed method

• Partition irregular building footprints into regular subregions using topological skeletons and a directed partition graph.
• Compute conformal maps for each subregion with Schwarz–Christoffel mapping to create level-set ribbons and sector boundaries.
• Stitch level-set maps across neighboring subregions to form a unified conformal layout for the lens.
• Overlay temporal displays onto facades as layered, concentric ribbons encoding time progression in a polar-based axis.
• Implement a view-dependent cutaway to suppress self-occluding geometry and maintain visibility of the temporal data.
• Evaluate the approach with a controlled user study comparing against juxtaposition and x-ray spatiotemporal designs.

Experimental results

Research questions

• RQ1 How does occlusion-free conformal lens visualization compare to conventional juxtaposition and x-ray designs in terms of task accuracy and completion time?
• RQ2 Does embedding temporally varying data on building footprints via conformal mappings enhance rapid time-space association in 3D urban analytics?
• RQ3 To what extent does view-dependent cutaway de-occlusion improve spatial orientation and reduce navigation effort during spatiotemporal analysis?
• RQ4 What are the design trade-offs and user-perceived benefits of embedding temporal plots within irregular urban geometries using conformal ribbons?

Key findings

• The lens approach improves task accuracy and reduces completion time compared to conventional designs.
• The visualization reduces navigation effort and increases user confidence in interpreting spatiotemporal urban data.
• Conformal mapping and layered ribbons enable coherent embedding of time-series data on building facades while preserving spatial orientation.
• The view-dependent cutaway supports occlusion-free perception without excessively distorting surrounding spatial context.
• The study yields design recommendations and outlines promising directions for future research on spatially-embedded lenses in urban analytics.