A Study of Opacity Ranges for Transparent Overlays in 3D Landscapes

TL;DR

This study investigates how different visual factors affect the acceptable opacity levels of overlays in 3D landscapes, providing guidelines for designing effective and unobtrusive data visualizations.

Contribution

It systematically examines the impact of pattern type, density, outlines, background, and opacity on overlay visibility in 3D environments, establishing preliminary design guidelines.

Findings

Acceptable opacity ranges are approximately 20-70%.

Adding an outline can extend acceptable opacity by about 5%.

Pattern and density influence the opacity ranges.

Abstract

{When visualizing data in a realistically rendered 3D virtual environment, it is often important to represent not only the 3D scene but also overlaid information about additional, abstract data. These overlays must be usefully visible, i.e. be readable enough to convey the information they represent, but remain unobtrusive to avoid cluttering the view. We take a step toward establishing guidelines for designing such overlays by studying the relationship between three different patterns (filled, striped and dotted patterns), two pattern densities, the presence or not of a solid outline, two types of background (blank and with trees), and the opacity of the overlay. For each combination of factors, participants set the faintest and the strongest acceptable opacity values. Results from this first study suggest that i) ranges of acceptable opacities are around 20-70%, that ii) ranges can be extended by 5% by using an outline, and that iii) ranges shift based on features like pattern and density.