14,391 research outputs found
Data visualization within urban models
Models of urban environments have many uses for town planning, pre-visualization of new building work and utility service planning. Many of these models are three-dimensional, and increasingly there is a move towards real-time presentation of such large models. In this paper we present an algorithm for generating consistent 3D models from a combination of data sources, including Ordnance Survey ground plans, aerial photography and laser height data. Although there have been several demonstrations of automatic generation of building models from 2D vector map data, in this paper we present a very robust solution that generates models that are suitable for real-time presentation. We then demonstrate a novel pollution visualization that uses these models
The Infrared Cloud Monitor for the MAGNUM Robotic Telescope at Haleakala
We present the most successful infrared cloud monitor for a robotic
telescope. This system was originally developed for the MAGNUM 2-m telescope,
which has been achieving unmanned and automated monitoring observation of
active galactic nuclei at Haleakala on the Hawaiian island of Maui since 2001.
Using a thermal imager and two aspherical mirrors, it at once sees almost the
whole sky at a wavelength of . Its outdoor part is
weather-proof and is totally maintenance-free. The images obtained every one or
two minutes are analysed immediately into several ranks of weather condition,
from which our automated observing system not only decides to open or close the
dome, but also selects what types of observations should be done. The whole-sky
data accumulated over four years show that 5060 % of all nights are
photometric, and about 75 % are observable with respect to cloud condition at
Haleakala. Many copies of this system are now used all over the world such as
Mauna Kea in Hawaii, Atacama in Chile, and Okayama and Kiso in Japan.Comment: 18 pages, 15 figures, 7 tables, accepted for publication in PAS
Shadow mapping algorithms: Applications and limitations
This study provides an overview of popular and famous algorithms and techniques in shadow maps generation.Well- known techniques in shadow maps generation is described detail, along with a discussion of the advantages and drawbacks of each. Basic ideas, improvements and future works of the techniques are also comprehensively summarized and analyzed in depth. Often, programmers have difficulty selecting an appropriate shadow generation algorithm that is specific to their purpose. We have classified and systemized these techniques. The main goal of this paper is to provide researchers with background on a variety of shadow mapping techniques so as make it easier for them to choose the method best suited to their aims. It is al-so hoped that our analysis will help researchers find solutions to the shortcomings of each technique. © 2015 NSP Natural Sciences Publishing Co
A Real-time Method for Inserting Virtual Objects into Neural Radiance Fields
We present the first real-time method for inserting a rigid virtual object
into a neural radiance field, which produces realistic lighting and shadowing
effects, as well as allows interactive manipulation of the object. By
exploiting the rich information about lighting and geometry in a NeRF, our
method overcomes several challenges of object insertion in augmented reality.
For lighting estimation, we produce accurate, robust and 3D spatially-varying
incident lighting that combines the near-field lighting from NeRF and an
environment lighting to account for sources not covered by the NeRF. For
occlusion, we blend the rendered virtual object with the background scene using
an opacity map integrated from the NeRF. For shadows, with a precomputed field
of spherical signed distance field, we query the visibility term for any point
around the virtual object, and cast soft, detailed shadows onto 3D surfaces.
Compared with state-of-the-art techniques, our approach can insert virtual
object into scenes with superior fidelity, and has a great potential to be
further applied to augmented reality systems
The Value of Scarce Water: Measuring the Inefficiency of Municipal Regulations
Rather than allowing water prices to reflect scarcity rents during periods of drought-induced excess demand, policy makers have mandated command-and-control approaches, like the curtailment of certain uses, primarily outdoor watering. Using unique panel data on residential end-uses of water, we examine the welfare implications of typical drought policies. Using price variation across and within markets, we identify end-use specific price elasticities. Our results suggest that current policies target water uses that households, themselves, are most willing to forgo. Nevertheless, we find that use restrictions have costly welfare implications, primarily due to household heterogeneity in willingness-to-pay for scarce water.
The Value of Scarce Water: Measuring the Inefficiency of Municipal Regulations
Rather than allowing water prices to reflect scarcity rents during periods of drought-induced excess demand, policy makers have mandated command-and-control approaches, like the curtailment of certain uses, primarily outdoor watering. Using unique panel data on residential end-uses of water, we examine the welfare implications of typical drought policies. Using price variation across and within markets, we identify end-use specific price elasticities. Our results suggest that current policies target water uses that households, themselves, are most willing to forgo. Nevertheless, we find that use restrictions have costly welfare implications, primarily due to household heterogeneity in willingness-to-pay for scarce water.
Multispectral RTI Analysis of Heterogeneous Artworks
We propose a novel multi-spectral reflectance transformation imaging (MS-RTI) framework for the acquisition and direct analysis of the reflectance behavior of heterogeneous artworks. Starting from free-form acquisitions, we compute per-pixel calibrated multi-spectral appearance profiles, which associate a reflectance value to each sampled light direction and frequency. Visualization, relighting, and feature extraction is performed directly on appearance profile data, applying scattered data interpolation based on Radial Basis Functions to estimate per-pixel reflectance from novel lighting directions. We demonstrate how the proposed solution can convey more insights on the object materials and geometric details compared to classical multi-light methods that rely on low-frequency analytical model fitting eventually mixed with a separate handling of high-frequency components, hence requiring constraining priors on material behavior. The flexibility of our approach is illustrated on two heterogeneous case studies, a painting and a dark shiny metallic sculpture, that showcase feature extraction, visualization, and analysis of high-frequency properties of artworks using multi-light, multi-spectral (Visible, UV and IR) acquisitions.Terms: "European Union (EU)" & "Horizon 2020" / Action: H2020-EU.3.6.3. - Reflective societies - cultural heritage and European identity / Acronym: Scan4Reco / Grant number: 665091the DSURF (PRIN 2015) project funded by the Italian Ministry of University and ResearchSardinian Regional Authorities under projects VIGEC and Vis&VideoLa
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