Hang Liu

• Liu, Hang; Laeng, Bruno & Czajkowski, Nikolai Olavi (2025). Visual short-term memory is modulated by 3D depth in stereopsis. Attention, Perception & Psychophysics. ISSN 1943-3921. 87(8), p. 2265–2274. doi: 10.3758/s13414-025-03052-3. Full text in Research Archive Show summary

  Visual short-term memory (VSTM) is a memory mechanism temporarily holding visual information for later use. In the real world, objects are located in spatial depth and such depth information may be processed when objects are remembered. The present study investigated how VSTM is modulated by three-dimensional (3D) depth. Previous work used the color of objects to measure memory and provided mixed results, and the impact of separability in depth on memory is unclear. In Experiment 1a, we employed color feature and examined the effect of 3D depth across Stereo (stereoscopic vs. monoscopic) and Plane (one plane vs. multiple planes). VSTM was not found to be influenced by depth information. In Experiments 1b and 1c, the color was respectively replaced with two distinct spatial features, orientation and direction-of-rotation. We found similar results that the performance on VSTM was superior in the stereoscopic multi-plane condition compared to the monoscopic multi-plane condition or stereoscopic single-plane condition. These findings confirm, also via Bayesian statistical analyses, that the VSTM can benefit from 3D depth information in stereopsis, while the benefit is severely limited when the task is non-spatial.

• Uggla, Maria; Olsson, Perola; Abdi, Barzan; Axelsson, Björn; Calvert, Matthew & Christensen, Ulrika [Show all 26 contributors for this article] (2023). Future Swedish 3D City Models—Specifications, Test Data, and Evaluation. ISPRS International Journal of Geo-Information. ISSN 2220-9964. 12(2), p. 1–35. doi: 10.3390/ijgi12020047. Full text in Research Archive Show summary

  Three-dimensional city models are increasingly being used for analyses and simulations. To enable such applications, it is necessary to standardise semantically richer city models and, in some cases, to connect the models with external data sources. In this study, we describe the development of a new Swedish specification for 3D city models, denoted as 3CIM, which is a joint effort between the three largest cities in Sweden—Stockholm, Gothenburg, and Malmö. Technically, 3CIM is an extension of the OGC standard CityGML 2.0, implemented as an application domain extension (ADE). The ADE is semantically thin, mainly extending CityGML 2.0 to harmonise with national standards; in contrast, 3CIM is mainly based on linkages to external databases, registers, and operational systems for the semantic part. The current version, 3CIM 1.0, includes various themes, including Bridge, Building, Utility, City Furniture, Transportation, Tunnel, Vegetation, and Water. Three test areas were created with 3CIM data, one in each city. These data were evaluated in several use-cases, including visualisation as well as daylight, noise, and flooding simulations. The conclusion from these use-cases is that the 3CIM data, together with the linked external data sources, allow for the inclusion of the necessary information for the visualisation and simulations, but extract, transform, and load (ETL) processes are required to tailor the input data. The next step is to implement 3CIM within the three cities, which will entail several challenges, as discussed at the end of the paper.

• Liu, Hang; Laeng, Bruno & Czajkowski, Nikolai Olavi (2020). Does stereopsis improve face identification? A study using a virtual reality display with integrated eye-tracking and pupillometry. Acta Psychologica. ISSN 0001-6918. 210. doi: 10.1016/j.actpsy.2020.103142. Full text in Research Archive Show summary

  Stereopsis is a powerful depth cue for humans, which may also contribute to object recognition. In particular, we surmise that face identification would benefit from the availability of stereoscopic depth cues, since facial perception may be based on three-dimensional (3D) representations. In this study, a virtual reality (VR) headset with integrated eye-tracking was used to present stereoscopic images of faces. As a monoscopic contrast condition, identical images of faces were displayed to the two eyes. We monitored the participants' gaze behavior and pupil diameters while they performed a sample-to-match face identification task. We found that accuracy was superior in the stereoscopic condition compared to the monoscopic condition for frontal and intermediate views, but not profiles. Moreover, pupillary diameters were smaller when identifying stereoscopically seen faces than when viewing them without stereometric cues, which we interpret as lower processing load for the former than the latter conditions. The analysis of gaze showed that participants tended to focus on regions of the face rich in volumetric information, more so in the stereoscopic condition than the monoscopic condition. Together, these findings suggest that a 3D representation of faces may be the natural format used by the visual system when assessing face identity. Stereoscopic information, by providing depth information, assists the construction of robust facial representations in memory.

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