Implementation of a 3D WebGIS for Dynamic Geo-Referencing of 3D Tiles on the Virtual Globe

Needs for real-time interactive visualization of 3D Tiles for massive 3D content on the web-based virtual globe is rapidly increasing, and to achieve this goal, 3D Tiles needs to be correctly geo-referenced to other geospatial data on a web-based virtual globe. It is possible to generate 3D Tiles from different kinds of spatial data through various software tools. However, due to various factors the 3D Tile datasets are often poorly or not at all geo-referenced. To tackle this issue, we propose a new 3D WebGIS framework that facilitates dynamic geo-referencing 3D Tiles on the CesiumJS virtual globe.

A New Independent GPS-Free System for Geo-Referencing from Space

A new system’s geo-referencing from space is entirely free from any GNSS (GPS or equivalent) systems. The system addresses to various strategic and economic applications such as in remote clock synchronism, aircraft and balloon navigation, missile and smart bombs tracking, satellite orbital determination and remote target geo-positioning. The new geometry concept corresponds to an “inverted GPS” configuration, utilizing four ground-based reference stations, synchronized in time, installed at well known geodesic coordinates and a repeater in space, carried by an aircraft, balloon, satellite, etc. Signal transmitted by one of the reference bases is retransmitted by the transponder, received back by the four bases, producing four ranging measurements which are corrected for the time delays undergone in every retransmission. A minimization function was derived to compare the repeater’s positions referred to at least two groups of three reference bases, to correct for the signal transit time at the repeater and propagation delays, and consequently to provide the accurate repeater position for each time interaction. Once the repeater’s coordinates are known, the other determinations and applications become straightforward. The system solving algorithm and process performance has been demonstrated by simulations adopting a practical example with the transponder carried by an aircraft moving over bases and a target on the ground. Effects produced by reference clock synchronism uncertainties at the four bases on the measurements are reviewed.

GEO-REFERENCING WITHOUT GROUND CONTROL

A geo-reference is a global or regional geographical or geodetic coor-dinate system to which sensors or spatial object data are related.Hence,geo-ref-erencing is close to the well known photogrammetric concept of exterior or abso-lute orientation,the common execution of which is indirect,via the use of groundcontrol point.GPS and INS technologies have changed the situation,permittingdirect measurement of position and attitude parameters and making exterior orien-tation feasible without ground control at all,in principle.The analysis of accuracyand reliability performance discloses,however,that especially INS does not yetmeet the high demands of photogrammetry.Moreover,control of systematic er-rors,the problem of datum transformation,and reliability conditions make theuse of some ground control points still mandatory,at least for any high perfor-mance geo-referencing.

Methods of 3D map storage based on geo-referenced image database

In order to store and manage a large amount of ground and indoor image data with high resolution, an integrated data management system needs to be developed. Possible strategies for this purpose were discussed together with initial test on the newly defined 3D maps. The features of such 3D maps, data organization, key techniques used for the map storage, such as image compression based on wavelet transformation, quadtree index, update and retrieval, were analyzed, with the goals of bringing some profits to the storage and management of the digital data in the visual construction of digital mine, digital city and digital community.

Environmental and Geo-Referenced Information Modeling for Sustainable Development in Iran

By providing Geo-referenced information, which serves as an important tool for decision-making in land use planning, national mapping agencies can help provide effective monitoring of environmental resources while in many parts of the world lack adequate information in clear. Their role in sustainability and development planning is thus unique and es- sential. National cartographic centers and national mapping agencies offers example of such national mapping agencies. Accurate information on land and environmental resources is essential to effective land use planning. Key sources of in- formation include topographic maps, aerial photos, satellite images, and data derived from geographic information sys- tems (GIS). At the national level, this information can be used to identify environmental resources, reveal the develop- ment potential of the country, and help promote effective ecological studies and sound land use planning with a land use planning approach. This article begins with some general comments on the importance of land use planning, and outli- nes some current environmental issues and also highlights the connection between roles of Geo-referenced information in land use planning with a sustainable development approach. The discussion describes several key methods of resour- ce identification, with particular emphasis on aerial photography and the existing potentials of Iran in this field. The ar- ticle also discusses the role that the Geo-referenced information and environmental planning play in developing and promoting geographic information system use to sustainable development and finally present proper models to use en- vironmental information and geo-referenced data for sustainable development.

Grayscale Mapping of Historically Irrigated LandsUsing GIS

This document describes the use of grayscale mapping and GIS for identification of historical irrigated lands. Historical irrigated lands form the basis for water rights—a private property right in New Mexico that is bought and sold on the open market. Identification of irrigated land on historical photography is both a science and an art. Grayscale mapping of historic black and white photographs can aid in the identification of irrigated lands. GIS allows historical images to be geo-referenced and area computations to be performed on polygons that define the irrigated lands.

Crowd Monitoring System Using Unmanned Aerial Vehicle （UAV）

Understanding and dealing with safety aspects of crowd dynamics in mass gatherings of people related to sports, religiousand cultural activities is very important, specifically with respect to crowd risk analysis and crowd safety. Historical trends from theKingdom of Saudi Arabia hosting millions of pilgrims each year during the Hajj and Omrah seasons suggest that stampedes in massgatherings occur frequently and highlight the importance of studying and dealing with the crowd dynamics more scientifically. In thisregard, efficient monitoring and other safe crowd management techniques have been used to minimize the risks associated with suchmass gathering. An example of these techniques is real-time monitoring of crowd using a UAV （Unmanned Aerial Vehicle）; thistechnique is becoming increasingly popular with the objective to save human lives, preserve environment, protect property, keep thepeace, and uphold governmental authority. In this paper, a crowd monitoring system for pedestrians has been proposed and tested. Thesystem has deployed crowd monitoring technique using real-time images taken by UAVs; the collected data was investigated, andcrowd density was estimated using image segmentation procedures. A color-based segmentation method has been employed to detect,identify and map crowd density under different camera positions and orientations. Furthermore, the associated anomalies/outlierswhich may lead to non-classification of features have been eliminated using image enhancement tools. The paper presents a crowdmonitoring system for pedestrians that can contribute to an area of research still in its infancy. The proposed system is a valuable tool interms of facilitating timely decisions, based on highly accurate information. The results show that the used image segmentationtechnique has the capability of mapping the crowd density with an accuracy level up to 80%.

Mapping Vehicular Noise Pollution in Port Harcourt Metropolis, Rivers State, Nigeria: Implication for a Sustainable Urbanization

This study aims to investigate geo-referenced vehicular noise pollution in the Port Harcourt metropolis of Rivers State,Nigeria.Three types of data were gathered for this study.Data from vehicular traffic noise were measured in decibels(dB)using Noise Dosimeter(ND);data from vehicular traffic counts were carried out by observing and counting traffic flow at junctions and roundabouts as well as vehicular traffic noise location map was established by using Global Positioning System(GPS)instrument processed in the Geographic Information System(GIS)environment.The findings indicated that in the northern segment,Igwurita(99.5 dB)and New road roundabout(96 dB),generated the highest vehicular noise in the spatial distribution.In the eastern road segments,Eleme Flyover(98.1 dB)and Artillery Junction(95.5 dB)contributed the highest vehicular noise levels.In the northern segment,New Road(2311 vehicles)and Igwuruta(1566 vehicles)at the roundabouts,generated the highest vehicular traffic counts in the spatial distribution.Thus,among the eastern roads,Eleme Flyover(6735 vehicles)and Artillery Junction(5539 vehicles)contributed the highest vehicular counts in the area.The results showed that the northern and eastern segments of the Port Harcourt metropolis had the highest level of vehicular traffic noise and traffic flow.Thus,the vehicular noise level values have exceeded the recommended 75 dB national and international health standards.The study recommended the construction of more road networks in the southern and western parts of the Port Harcourt metropolis to decongest traffic flow and noise pollution in the northern and eastern segments of the city.