Procedural modeling applied to the 3D city model of Bogota:A case study

Background Computer Generated Animations(CGA),when applied to three-dimensional(3D)city models(3DCM),can be used as powerful tools to support urban decision-making.This leads to a new paradigm,based on procedural modeling,that allows the integration of known urban structures.Methods This paper introduces a new workflow for the development of high-quality approximations of urban models in a short time and enables facilities to be imported from other cities into a given city model,following specific generation rules.Results Thus,this workflow provides a very simple approach to observe,study,and simulate the implementation of models already developed in other cities,in a city where they are not yet adopted.Examples of these models include all types of mobility systems and urban infrastructure.Conclusions This allows us to perceive the environmental impact of certain decisions in the real world,as well as to carry out simple simulations to determine the changes that can occur in the flows of people,traffic,and other city activities.

Unified Data Model of Urban Air Pollution Dispersion and 3D Spatial City Model:Groundwork Assessment towards Sustainable Urban Development for Malaysia

Understanding the behavior of urban air pollution is important en route for sustainable urban development (SUD). Malaysia is on its mission to be a developed country by year 2020 comprehends dealing with air pollution is one of the indicators headed towards it. At present monitoring and managing air pollution in urban areas encompasses sophisticated air quality modeling and data acquisition. However, rapid developments in major cities cause difficulties in acquiring the city geometries. The existing method in acquiring city geometries data via ground or space measurement inspection such as field survey, photogrammetry, laser scanning, remote sensing or using architectural plans appears not to be practical because of its cost and efforts. Moreover, air monitoring stations deployed are intended for regional to global scale model whereby it is not accurate for urban areas with typical resolution of less than 2 km. Furthermore in urban areas, the pollutant dispersion movements are trapped between buildings initiating it to move vertically causing visualization complications which imply the limitations of existing visualization scheme that is based on two-dimensional (2D) framework. Therefore this paper aims is to perform groundwork assessment and discuss on the current scenario in Malaysia in the aspect of current policies towards SUD, air quality monitoring stations, scale model and detail discussion on air pollution dispersion model used called the Operational Street Pollution Model (OSPM). This research proposed the implementation of three-dimensional (3D) spatial city model as a new physical data input for OSPM. The five Level of Details (LOD) of 3D spatial city model shows the scale applicability for the dispersion model implementtation. Subsequently 3D spatial city model data commonly available on the web, by having a unified data model shows the advantages in easy data acquisition, 3D visualization of air pollution dispersion and improves visual analysis of air quality monitoring in urban areas.

Design of Wuzhou Arcade Naturalist City Display Based on 3D Panoramic Technology

This paper taking Wuzhou arcade naturalist city as design sight spot, made a on location shoot on the streetscape of arcade naturalist city. then synthesized them by software in panoramic way. to create a multimedia virtual exhibition platform. This paper has explored the used digital software and forms of artistic expression in this system, summed up the experience in the production of shooting, image stitching, and image post-processing as well ss art design, and finally combined with the Lingnan culture features to design the arcade naturalist city show platform.

An Automated Process of Creating 3D City Model for Monitoring Urban Infrastructures

This paper describes the process of designing models and tools for an automated way of creating 3D city model based on a raw point cloud.Also,making and forming 3D models of buildings.Models and tools for creating tools made in the model builder application within the ArcGIS Pro software.An unclassified point cloud obtained by the LiDAR system was used for the model input data.The point cloud,collected by the airborne laser scanning system(ALS),is classified into several classes:ground,high and low noise,and buildings.Based on the created DEMs,points classified as buildings and formed prints of buildings,realistic 3D city models were created.Created 3D models of cities can be used as a basis for monitoring the infrastructure of settlements and other analyzes that are important for further development and architecture of cities.

A Preliminary Review on Three-Dimensional City Model

In this paper a review on current research on 3DCM is presented, and an alternative approach by integrating the concepts and techniques of object\|oriented method and Computer Aided Design (CAD) is suggested. Through the approach urban spatial entities as objects are extracted, which are represented with primary 3D elements (node, edge, face and body) and their combinations. In the light of the concept of object, the method supports the multiple representation of Level of Details (LOD). More importantly, topological relationships between objects are described so that 3D topological operations can be implemented.

Real-time visualization of 3D city models at street-level based on visual saliency

Street-level visualization is an important application of 3D city models.Challenges to street-level visualization include the cluttering of buildings due to fine detail and visualization performance.In this paper,a novel method is proposed for streetlevel visualization based on visual saliency evaluation.The basic idea of the method is to preserve these salient buildings in a scene while removing those that are non-salient.The method can be divided into pre-processing procedures and real-time visualization.The first step in pre-processing is to convert 3D building models at higher Levels of Detail(Lo Ds) into LoD 1 models with simplified ground plans.Then,a number of index viewpoints are created along the streets; these indices refer to both the position and the direction of each street site.A visual saliency value is computed for each building,with respect to the index site,based on a visual difference between the original model and the generalized model.We calculate and evaluate three methods for visual saliency:local difference,global difference and minimum projection area.The real-time visualization process begins by mapping the observer to its closest indices.The street view is then generated based on the building information stored in those indexes.A user study shows that the local visual saliency method performs better than do the global visual saliency,area and image-based methods and that the framework proposed in this paper may improve the performance of 3D visualization.

A virtual globe-based time-critical adaptive visualization method for 3D city models

3D city models,which are important items of content on the virtual globe,are characterized by complicated structures and large amounts of data.These factors make the visualization of 3D city models highly dependent upon the performance of computer hardware.Thus,achieving the efficient rendering of 3D city models using different hardware performance levels represents one of the key problems currently facing researchers.This paper proposes a time-critical adaptive visualization method that first estimates the possible rendering time for each model according to the data structure of the model in addition to the CPU/GPU performance of the computer.It then dynamically adjusts the rendering level for each model based on the results of an estimation of the rendering time to ensure that the final scene can be completed within a given time.To verify the effectiveness and flexibility of this method,it is applied using different computers.The results show that the adaptive visualization method presented in this paper not only can adapt to computers with different levels of performances but also demonstrates an obvious improvement in the time estimation precision,visual effects,and optimization speed relative to existing adaptive visualization methods.

Research and Practice in Three-Dimensional City Modeling

The way we interact with spatial data has been changed from 2D map to 3D Virtual Geographic Environment （VGE）. Three-dimensional representations of geographic information on a computer are known as VGE, and in particular 3D city models provide an efficient way to integrate massive, heterogenous geospatial information and georeferenced information in urban areas. 3D city modeling （3DCM） is an active research and practice topic in distinct application areas. This paper intro- duces different modeling paradigms employed in 3D GIS, virtual environment, and AEC/FM. Up-to-date 3DCM technologies are evolving into a data integration and collaborative approach to represent the full spatial coverage of a city, to model both aboveground and underground, outdoor and indoor environments including man-made objects and natural features with 3D geometry, appearance, topology and semantics.

GeoScope:Full 3D Geospatial Information System Case Study

Aiming at the integrative management and comprehensive applications of large-scale 3D geospatial information covering the full 3D space of a city, this paper briefly introduces the design and implementation of a full 3D GIS platform： GeoScope, which provides a professional solution for the massive full three-dimensional geospatial data integration, management, analysis, visualization, and applications. GeoScope is characterized by： （1） extendible software architecture based on the hierarchical message bus, facilitates multimodal integrative applications of 2D GIS and 3D GIS; （2） unified 3D city models, support multiscale se- mantic representation of outdoor ＆ indoor and aboveground ＆ underground 3D objects; （3） high-efficient 3D geospatial database engine, supports integrated management of massive 3D geospatial data for real-time applications; and （4） high-performance visualization engine exploiting the massively parallel computation architecture of modem GPUs, supports real-time realistic rendering of large-scale complicated 3D geospatial environments. The successful pilot application of GeoScope is also illustrated with the 3D city models of 8494 knl2 of the whole Wuhan City, the largest city in middle China.

Improving accuracy of automated 3-D building models for smart cities

Photorealistic three-dimensional(3-D)models are important tools for urban and disaster management planning because they contain useful visual and spatial information for assessing the situation and responding accordingly.Thus,it is crucial for 3-D city models to maintain a high level of accuracy in portraying 3-D geometric objects.Despite that,significant research with respect to 3-D city models has been conducted;however,it is still difficult to create accurate 3-D representations,particularly across a wide area.Thus,this research is aimed at developing an automated 3-D city modeling application that utilizes a combination of aerial photographs,terrestrial light detection and ranging,and total station techniques for particularly dense urban areas.To enable the development of an automated 3-D city model,this research developed application software programmed in C++.This application enables users to generate 3-D images of buildings.Specifically,the 3-D city models are generated using the aerial photographs.The positional accuracy of the model is highly improved by comparing building models produced using a photogrammetric plotting instrument.Once created using a combination of aerial photos and terrestrial instruments,the 3-D city model is quantitatively assessed for completeness and suitability for commercial or public use.

Three-dimensional CityGML building models in mobile augmented reality: a smartphone-based pose tracking system

Many augmented reality(AR)systems are developed for entertainment,but AR and particularly mobile AR potentially have more application possibilities in other fields.For example,in civil engineering or city planning,AR could be used in combination with CityGML building models to enhance some typical workflows in planning,execution and operation processes.A concrete example is the geo-referenced on-site visualization of planned buildings or building parts,to simplify planning processes and optimize the communication between the participating decision-makers.One of the main challenges for the visualization lies in the pose tracking,i.e.the real-time estimation of the translation and rotation of the mobile device to align the virtual objects with reality.In this paper,we introduce a proof-of-concept fine-grained mobile AR CityGML-based pose tracking system aimed at the mentioned applications.The system estimates poses by combining 3D CityGML data with information derived from 2D camera images and an inertial measurement unit and is fully self-sufficient and operates without external infrastructure.The results of our evaluation show that CityGML and low-cost off-the-shelf mobile devices,such as smartphones,already provide performant and accurate mobile pose tracking for AR in civil engineering and city planning.

Skyline-Based Registration of 3D Laser Scans

Acquisition and registration of terrestrial 3D laser scans is a fundamental task in mapping and modeling of cities in three dimensions. To automate this task marker-flee registration methods are required. Based on the existence of skyline features, this paper proposes a novel method. The skyline features are extracted from panoramic 3D scans and encoded as strings enabling the use of string matching for merging the scans. Initial results of the proposed method in the old city center of Bremen are presented.

Reality-based generation of virtual environments for digital earth

Digital Earth essentially consists of 3D and moreD models and attached semantic information(attributes).Techniques for generating such models efficiently are required very urgently.Reality-based 3D modelling using images as prime data source plays an important role in this context.Images contain a wealth of information that can be advantageously used for model generation.Images are increasingly available from satellite,aerial and terrestrial platforms.This contribution briefly describes some of the problems which we encounter if the process of model generation is to be automatised.With the help of some examples from Digital Terrain Model generation,Cultural Heritage and 3D city modelling we show briefly what can be achieved.Special attention is directed towards the use of model helicopters for image data acquisition.Some problems with interactive visualisation are discussed.Also,issues surrounding R&D,professional practice and education are also addressed.