Visualisation of urban airborne laser scanning data with occlusion images

Hinks, Tommy; Carr, Hamish; Gharibi, Hamid; Laefer, Debra F.

doi:10.1016/j.isprsjprs.2015.01.014

Cited by 14 publications

(8 citation statements)

References 24 publications

(25 reference statements)

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“…The parts that are more occluded appear darker than the parts that are more exposed. Ambient occlusion was successfully applied not only in 3-D computer graphics for visualizing molecular surface (Tarini et al, 2006), objects of cultural heritage (Callieri et al, 2011), but also DEMs derived from airborne laser scanning data (Hinks et al, 2015). DEM_CH, int = 0.5 DEM_CH_CONTOURS_05 r.geomorphon dem = "DEM_CH", forms = "DEM_CH_CLASS", search = 20, skip = 4 DEM_CH_CLASS r.mapcalc DEM_CH_CLASS = 3||DEM_CH_CLASS = 2 DEM_CLASS_23 r.clump input = "DEM_CLASS_2_3" DEM_CH_CLASS_23_CLUMP r.stats.zonal cover = "DEM_CH", base ="DEM_CH_CLASS", method = mean DEM_CH_CLASS_23_CLUMP_ELV…”

Section: Analysing the Cave Surface Using 3-d Geomorphometrymentioning

confidence: 99%

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

Gallay

Hochmuth

Kaňuk

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. The change of hydrological conditions during the evolution of caves in carbonate rocks often results in a complex subterranean geomorphology, which comprises specific landforms such as ceiling channels, anastomosing half tubes, or speleothems organized vertically in different levels. Studying such complex environments traditionally requires tedious mapping; however, this is being replaced with terrestrial laser scanning technology. Laser scanning overcomes the problem of reaching high ceilings, providing new options to map underground landscapes with unprecedented level of detail and accuracy. The acquired point cloud can be handled conveniently with dedicated software, but applying traditional geomorphometry to analyse the cave surface is limited. This is because geomorphometry has been focused on parameterization and analysis of surficial terrain. The theoretical and methodological concept has been based on twodimensional (2-D) scalar fields, which are sufficient for most cases of the surficial terrain. The terrain surface is modelled with a bivariate function of altitude (elevation) and represented by a raster digital elevation model. However, the cave is a 3-D entity; therefore, a different approach is required for geomorphometric analysis. In this paper, we demonstrate the benefits of high-resolution cave mapping and 3-D modelling to better understand the palaeohydrography of the Domica cave in Slovakia. This methodological approach adopted traditional geomorphometric methods in a unique manner and also new methods used in 3-D computer graphics, which can be applied to study other 3-D geomorphological forms.

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Section: Analysing the Cave Surface Using 3-d Geomorphometrymentioning

confidence: 99%

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

Gallay

Hochmuth

Kaňuk

et al. 2016

Hydrol. Earth Syst. Sci.

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“…While shadow analysis is a well-studied subject supported by a large body of literature, computing shadows for large scenes, such as urban environments particularly when the computation is needed over a large temporal extent, has remained a challenge (Hinks et al, 2015;Miranda et al, 2019). In a recently published study on large-scale urban shadow analysis, to reduce the computational burden, Miranda et al (2019) proposed using a 3D vector model of New York City (NYC), in which the majority of structures are represented by CityGML's Level of Detail 1 (LoD 1) with several segments represented at LoD 2 (NYC Department of City Planning, 2018).…”

Section: Related Workmentioning

confidence: 99%

A Big Data Approach for Comprehensive Urban Shadow Analysis From Airborne Laser Scanning Point Clouds

Laefer

2019

ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci.

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<p><strong>Abstract.</strong> Because of the importance of access to sunlight, shadow analysis is a common consideration in urban design, especially for dense urban developments. As shadow computation is computationally expensive, most urban shadow analysis tools have to date circumvented the high computational costs by representing urban complexity only through simplified geometric models. The simplification process removes details and adversely affects the level of realism of the ultimate results. In this paper, an alternative approach is presented by utilizing the highest level of detail and resolution captured in the geometric input data source, which is an extremely high-resolution airborne laser scanning point cloud (300 points/m2). To cope with the high computational demand caused by the use of this dense and detailed input data set, the Comprehensive Urban Shadow algorithm is introduced to distribute the computation for parallel processing on a Hadoop cluster. The proposed comprehensive urban shadow analysis solution is scalable, reasonably fast, and capable of preserving the original resolution and geometric detail of the original point cloud data.</p>

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“…The flight campaign was planned using approaches described in Hinks et al (2009) to adapt ALS to the complexity of urban areas by improving the visualization of small details of the environment and maximizing data coverage of building façades, which involved a 67% overlap in straight tracks oriented with a 45º offset with respect to the predominant street axes, to minimize self-shadowing effects. Captured from a rotary platform at approximately 300 with a 30º scanning angle, most location are captured six times from unique sky locations (Hinks et al 2015). All flightlines are shown in Fig.…”

Section: Study Datamentioning

confidence: 99%

Automatic extraction of road features in urban environments using dense ALS data

Soilán

Truong-Hong

Riveiro

et al. 2018

International Journal of Applied Earth Observation and Geoinfor

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This paper describes a methodology that automatically extracts semantic information from urban ALS data for urban parameterization and road network definition. First, building façades are segmented from the ground surface by combining knowledge-based information with both voxel and raster data. Next, heuristic rules and unsupervised learning are applied to the ground surface data to distinguish sidewalk and pavement points as a means for curb detection. Then radiometric information was employed for road marking extraction. Using high-density ALS data from Dublin, Ireland, this fully automatic workflow was able to generate a F-score close to 95% for pavement and sidewalk identification with a resolution of 20cm and better than 80% for road marking detection.

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Visualisation of urban airborne laser scanning data with occlusion images

Cited by 14 publications

References 24 publications

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

Geomorphometric analysis of cave ceiling channels mapped with 3-D terrestrial laser scanning

A Big Data Approach for Comprehensive Urban Shadow Analysis From Airborne Laser Scanning Point Clouds

Automatic extraction of road features in urban environments using dense ALS data

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