The present study evaluates a methodological workflow that could identify dinosaur tracks and trackways more comprehensively at outcrop scale. The approach described here is based both on 3D modelling by photogrammetry at different resolutions, and on suitably processed digital elevation models (DEMs). The ichnosite of Anza, Morocco, was chosen to demonstrate the efficiency of the proposed pipeline, because 323 dinosaur and pterosaur tracks discovered there have already been published. One subsector containing 89 tracks, identified in the two companion works that followed a traditional approach, was selected and divided into four subzones. By combining different DEM processes (hill-shade, slope, sky-view factor, and positive openness), almost twice as many tracks (175 vs 89) are now identified in these subzones. However, the improvement is not homogeneous. In the first subzone, the previous works reported 25 tracks vs. 22 with the 3D modelling techniques used here, whereas results for the second and third subzones show considerable improvement with 3D (21 vs 38 tracks and 42 vs 81 tracks, respectively). The enhancement is even more dramatic for the fourth subzone, where 34 new tracks are now identified, whereas with the traditional approach, only one track was previously reported. It is likely that such improvements depend on several factors, i.e. the surface conditions of the rocks (e.g. irregularities, cracking, etc.), and on the preservation state and depth of the tracks. Morphometric measurements of tracks and trackways obtained from 3D models are very similar to those derived from traditional fieldwork methods. The digital approach can be applied rapidly at different resolutions, but the models acquired with the pole-mounted camera provide a good compromise, with a resolution high enough (~2 mm/pix) to spot tracks, while respecting computational constraints. Once treated, DEMs greatly facilitate the reproduction of track outlines, drawn according to criteria defined by the operator.
Navigational systems guide users providing visual and acoustic indications, burdening user’s attention. On the one hand, following visual guidance is challenging because of the constant need to switch the gaze between the display and the surroundings. On the other hand, auditory indications can be obtrusive and inefficient. Tactile displays, i.e., systems that send stimuli via the tactile channel, can overcome such limitations. They are useful when the visual and auditory attention is limited and they can deliver precise spatial information in an unobtrusive manner all around the user. Navigational systems deploying tactile guidance have been experimented with different devices (e.g., hand-held devices, belts, armband and wristband). Here we compared a tactile vest and a tactile glove in guiding users through an itinerary in an urban setting. Twenty-four people (9 males) participated in the study (mean age 24.37, SD= 2.24). Our findings show that the both devices are efficient as navigation tool. Despite both devices were well-received by users, their appearance was relevant. The vest was in fact praised for the clearness of the indications, while the glove was preferred for being unbulky and light-weighted.
In the context of activity recognition, wearable devices are nowadays the preferable hardware thanks to their usability, user experience and performances; at the same time, these devices present limitations in terms of computational capability and memory, which force the algorithm design to be at the same time efficient and simple. In this work, we adopt Symbolic Aggregate Approximation (SAX), a symbolic approach for information retrieval in time series data that allows dimensionality and numerosity reduction; SAX is employed here, in combination with 1-Nearest Neighbor classifier, to identify activity phases in continuous repetitive activities from inertial time-series data. The proposed approach is validated on a cross-country skiing dataset and on a daily living activities dataset.
The availability of indexes linked to distinct mental functions suggests their use in the evaluation of the cerebral impact of human machine interface or devices by measuring the induced cerebral activity. This approach could reveal additional information concerning the efficacy evaluation of the proposed device or interface, beyond the participants' behavioral and verbal reports. The mental workload index (frontal EEG power spectra increase in the theta band and simultaneous parietal EEG power spectra decrease in the alpha band) is an example of these indexes and in this study it was employed to identify the most appropriate cochlear implant processor in one postlingually deaf 43 years old male unilateral CI user. Results were compared with those obtained in another study involving the selection of the most appropriate devices in a helicopter cockpit. Data showed a statistical significant difference between sound processors (Freedom, CP810 and CP910) (F(2,180) = 3,046 p=0.05. In addition, the trials in which the Noise filter reduction function was adopted reported statistically significantly lower IWL values in comparison to the trials with No noise filter reduction use (F(1,90) = 8,027 p = 0,006). The evidences support the capability of identifying the devices eliciting less workload level. Such devices would free up user's cognitive resources that will be available for other additional tasks.
It is well established that individuals tend to underestimate visually presented walking speeds when relying on treadmills for virtual walking. However, prior to the present studies this perceptual distortion had not been observed in relation to Walking-in-Place (WIP) locomotion, and a number of the factors contributing to the perceptual distortion have yet to be identified. In this paper we present a summary of seven of our studies investigating what factors that influence self-motion perception during virtual walking and two meta-analyses of the findings of the seven studies. The studies relate to how gait cycle characteristics, visual display properties, and methodological differences affect speed underestimation during treadmill and WIP locomotion. The studies suggested the following: A significant main effect was found for step frequency; both display and geometric field of view were inversely proportional to the degree of underestimation; varying degrees of peripheral occlusion and increased HMD weight did not yield significant main effects; and the choice of method (i.e., how the speeds were presented) had a significant effect on the upper and lower bounds of what speeds were perceived as natural. All seven studies compared treadmill and WIP locomotion and higher speeds were generally preferred during treadmill walking, but only some studies found a significant effect. Meta-analyses of the differences between the two movement types revealed a significant difference and provided pooled estimates of the magnitude of this difference.
