The Malta cistern mapping project: Underwater robot mapping and localization within ancient tunnel systems

White, Cory; Hiranandani, Daniel; Olstad, Christopher S.; Buhagiar, Keith; Gambin, Timmy; Clark, Christopher M.

doi:10.1002/rob.20339

Cited by 39 publications

(33 citation statements)

References 17 publications

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“…Specifically, the space being mapped is discretized into a two dimensional grid of cells with given a likelihood p i, j ∈ [0, 1] of being occupied (Thrun et al, 2005) and (White et al, 2010). The evidence grid is extrapolated into three dimensions to the appropriate height of the water system, and can then be treated as volume data, and geometric models of the scanned data can be constructed via marching cubes, similar to the work presented in (Forney et al, 2011).…”

Section: Algorithms and Practicementioning

confidence: 99%

“…Due to the importance of acquiring accurate data, stationary sonar scans were taken using a SeaSprite scanning sonar mounted on top of the ROV. These sonar measurements were used to generate evidence grids that in turn, were used to generate geometric models of the cisterns (McVicker et al, 2012) and (White et al, 2010), (Forney et al, 2011). For real world acquired data, a number of subtle challenges arise when applying hole filling to construct a complete water tight model.…”

Section: Hole Filling In Practicementioning

confidence: 99%

See 1 more Smart Citation

Uncertainty Visualization and Hole Filling for Geometric Models of Ancient Water Systems

Forrester¹,

McVicker²,

Gambin³

et al. 2013

Proceedings of the International Conference on Computer Graphics Theory and Applications and International Conference on Inform

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Abstract:Geometric data acquired via a scanning process can suffer from holes due to errors in the acquisition process, noise, or challenges in merging multiple inputs together into a unified map. We present a straight forward algorithm to fill holes in incomplete evidence grids representing acquired geometric data. We also present our methods to apply learning in order to statistically evaluate the proposed hole filling algorithm. This analysis validates our proposed method for hole filling and additionally enables the construction of a probability distribution function to represent the accuracy of the filled data per model. During surface reconstruction, this function can be used to visualize the certainty of the filled geometry via transparency and coloring giving the user an understanding of the data's accuracy. This work is motivated by a multi-year project to construct educational visualizations of ancient water storage systems, i.e. cisterns and wells within churches, fortresses and homes on the islands of Malta, Gozo and Sicily.

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Section: Algorithms and Practicementioning

confidence: 99%

Section: Hole Filling In Practicementioning

confidence: 99%

Uncertainty Visualization and Hole Filling for Geometric Models of Ancient Water Systems

Forrester¹,

McVicker²,

Gambin³

et al. 2013

Proceedings of the International Conference on Computer Graphics Theory and Applications and International Conference on Inform

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“…The goal of this project was to gather data about the underwater cisterns, and enable the creation of geometric models of the cisterns that could later be explored and visualized in a computer graphics application. This work builds from two previous expeditions [2], after which only two-dimensional maps were created.…”

Section: Introductionmentioning

confidence: 99%

Surface Reconstruction of Maltese Cisterns Using ROV Sonar Data for Archeological Study

Forney

Forrester

Bagley

et al. 2011

Advances in Visual Computing

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Abstract. We present a methodology and algorithm for the reconstruction of three dimensional geometric models of ancient Maltese water storage systems, i.e. cisterns, from sonar data. This project was conducted as a part of a four week expedition on the islands of Malta and Gozo. During this expedition, investigators used underwater robot systems capable of mapping ancient underwater cisterns and tunnels. The mapping included probabilistic algorithms for constructing the maps of the sonar data and computer graphics for surface reconstruction and visualization. This paper presents the general methodology for the data acquisition and the novel application of algorithms from computer graphics for surface reconstruction to this new data setting. In addition to reconstructing the geometry of the cisterns, the visualization system includes methods to enhance the understanding of the data by visualizing water level and texture detail either through the application of real image data via projective textures or by more standard texture mapping techniques. The resulting surface reconstructions and visualizations can be used by archaeologists for educational purposes and to help understand the shape and history of such water receptacles.

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“…In the previous expeditions dedicated to mapping Maltese cisterns [14], [15], [16] the mapping techniques included sonar mosaicking, and underwater robot SLAM with both a stationary and moving robot. Sonar mosaics are images generated by piecing together different parts (scans) of the image to create a single image.…”

Section: Introductionmentioning

confidence: 99%

“…For underwater robot SLAM, inadequate motion modeling led to reduced accuracy in robot localization and hence mapping [15]. To ensure highly accurate maps, the subsequent expeditions focussed on obtaining a series of stationary sonar scans from several positions in the tunnel [14].…”

Section: Introductionmentioning

confidence: 99%

Mapping and Visualizing Ancient Water Storage Systems with an ROV -- An Approach Based on Fusing Stationary Scans within a Particle Filter

McVicker

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Abstract-This paper presents a new method for constructing 2D maps of enclosed underwater structures using an underwater robot equipped with only a 2D scanning sonar, compass and depth sensor. In particular, no motion model or odometry is used. To accomplish this, a two step offline SLAM method is applied to a set of stationary sonar scans. In the first step, the change in position of the robot between each consecutive pair of stationary sonar scans is estimated using a particle filter. This set of pair wise relative scan positions is used to create an estimate of each scan's position within a global coordinate frame using a weighted least squares fit that optimizes consistency between the relative positions of the entire set of scans. In the second step of the method, scans and their estimated positions act as inputs to a mapping algorithm that constructs 2D octree-based evidence grid maps of the site. This work is motivated by a multi-year archeological project that aims to construct maps of ancient water storage systems, i.e. cisterns, on the islands of Malta and Gozo. Cisterns, wells, and water galleries within fortresses, churches and homes operated as water storage systems as far back as 2000 B.C. Using a Remotely Operated Vehicle (ROV) these water storage systems located around the islands were explored while collecting video, still images, sonar, depth, and compass measurements. Data gathered from 3 different expeditions has produced maps of over 60 sites. Presented are results from applying the new mapping method to both a swimming pool of known size and to several of the previously unexplored water storage systems.

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The Malta cistern mapping project: Underwater robot mapping and localization within ancient tunnel systems

Cited by 39 publications

References 17 publications

Uncertainty Visualization and Hole Filling for Geometric Models of Ancient Water Systems

Uncertainty Visualization and Hole Filling for Geometric Models of Ancient Water Systems

Surface Reconstruction of Maltese Cisterns Using ROV Sonar Data for Archeological Study

Mapping and Visualizing Ancient Water Storage Systems with an ROV -- An Approach Based on Fusing Stationary Scans within a Particle Filter

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