Planar to spatial geodesic grids

At the Center for Geometry and Computational Design (GCD) (Institute for Discrete Mathematics and Geometry) at TU Wien, Musialski and his team developed a method that can be used to calculate what the flat, two-dimensional grid must look like in order to produce exactly the desired three-dimensional shape when it is unfolded. “Our method is based on findings in differential geometry, it is relatively simple and does not require computationally intensive simulations,” says Stefan Pillwein, first author of the current publication.

Suppose you screw ordinary straight bars together at right angles to form a grid, so that a completely regular pattern of small squares is created. Such a grid can be distorted: all angles of the grid change simultaneously, parallel bars remain parallel, and the squares become parallelograms. But this does not change the fact that all bars are in the same plane. The structure is still flat.

The crucial question now is: What happens if the bars are not parallel at the beginning, but are joined together at different angles? “Such a grid can no longer be distorted within the plane,” explains Przemyslaw Musialski. “When you open it up, the bars have to bend. They move out of the plane into the third dimension and form a curved shape.”

At the Center for Geometry and Computational Design (GCD) (Institute for Discrete Mathematics and Geometry) at TU Wien, Musialski and his team developed a method that can be used to calculate what the flat, two-dimensional grid must look like in order to produce exactly the desired three-dimensional shape when it is unfolded. “Our method is based on findings in differential geometry, it is relatively simple and does not require computationally intensive simulations,” says Stefan Pillwein, first author of the current publication.

You can read more in the original paper (this version is adapted and abridged from Source).

Pillwein, S., Leimer, K., Birsak, M. and Musialski, P., 2020. On elastic geodesic grids and their planar to spatial deployment. arXiv preprint arXiv:2007.00201.

OpenVisSim, a sight-loss simulator

Modern digital simulators are able to replicate and objectively quantify some of the key everyday difficulties associated with visual impairments.

First row: virtual rooms from the simulator. Bottom row: smartphone highlighted in the first pannel, while the last 2 showcase superior and inferior visual field loss. Source

Over 100 million people worldwide live with a chronic visual impairment (VI). The most common causes are glaucoma, agerelated macular degeneration (AMD), and cataracts. Simulations are often used to help communicate the day-to-day challenges that visually impaired individuals may experience. The authors used a Head Mounted Display (HMD) with integrated eyetracking to perform gaze-contingent digital manipulations in virtual or augmented reality (VR/AR). Their software is freely available online (OpenVisSim), and provides a description of multiple different symptoms that can be simulated simultaneously and in real-time.

The current work is focused on glaucoma, because it is often misunderstood. Individuals with this condition often report particular difficulty locating objects in cluttered visual scenes, and also exhibit reduced mobility and increased risk of falls. Additionally, these difficulties tend to be most pronounced when the loss occurs in the inferior visual field, compared to when the loss of vision occurs above the midline. The experimental setup implies 28 individuals that had to perform two tasks in the simulator: object search (locate a smartphone in a house) and visual mobility (navigation). The results show that participants were slower to perform everyday visual-search (VR) and mobility (AR) tasks when experiencing simulated Visual Field Loss (VFL), and as with real patients these difficulties were exacerbated when the VFL was inferior.

Many participants reported feeling anxious when the impairment was active. This was particularly the case when participants were ascending/descending the stairs that led to the AR mobility platform. Interestingly, “climbing stairs” is also a regular source of anxiety for many people with severe vision loss.

You can read more in the original paper (this version is adapted and abridged).

Jones, P.R., Somoskeöy, T., Chow-Wing-Bom, H. and Crabb, D.P., 2020. Seeing other perspectives: evaluating the use of virtual and augmented reality to simulate visual impairments (OpenVisSim). NPJ digital medicine3(1), pp.1-9.

Preparing for the sandworms

Since the trailers for the 2020 movie adaptation of the book “Dune” (written by Frank Herbert, and published in 1965) were released, it is a good moment to refresh our memories and read the original work. Below is a creative animated summary of the plot, to get you started reading the series if you haven’t already. On the same note, if you haven’t watched the first movie which appeared in 1984, a great comparison between the old and new teasers will incite your curiosity to better understand what has changed (or not) in cinematography and storytelling.