29 research outputs found
Generalized, Inaccurate, Incomplete: How to Comprehensively Analyze Sketch Maps Beyond Their Metric Correctness
No full textSketch mapping is a method to investigate a person’s spatial perception and knowledge about the surrounding environment. While cartographic maps can be easily evaluated with respect to the represented features, map scale, and spatial accuracy, there still does not exist a comprehensive method to evaluate sketch maps. This paper aims to overcome this gap and proposes a sketch map analysis method that allows for analyzing the completeness, generalization and (qualitative) spatial accuracy of the sketched information in a three-step process. After describing the method, we illustrate how our computer-supported method performs in a use case with three sketch maps. Our approach may assist researchers in geography, psychology, and education to evaluate spatial knowledge in a systematic way independent of specific research questions and experimental scenarios
Framework development for providing accessibility to qualitative spatial calculi
No full textDissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Qualitative spatial reasoning deals with knowledge about an infinite spatial domain using a finite set of qualitative relations without using numerical computation. Qualitative knowledge is relative knowledge where we obtain the knowledge on the basis of comparison of features with in the object domain rather then using some external scales. Reasoning is an intellectual facility by which, conclusions are drawn from premises and is present in our everyday interaction with the geographical world. The kind of reasoning that human being relies on is based on commonsense knowledge in everyday situations. During the last decades a multitude of formal calculi over spatial relations have been proposed by focusing on different aspects of space like topology, orientation and distance.
Qualitative spatial reasoning engines like SparQ and GQR represents space and reasoning about the space based on qualitative spatial relations and bring qualitative reasoning closer to the geographic applications. Their relations and certain operations defined in qualitative calculi use to infer new knowledge on different aspects of space.
Today GIS does not support common-sense reasoning due to limitation for how to formalize spatial inferences. It is important to focus on common sense geographic reasoning, reasoning as it is performed by human. Human perceive and represents geographic information qualitatively, the integration of reasoner with spatial application enables GIS users to represent and extract geographic information qualitatively using human understandable query language.
In this thesis, I designed and developed common API framework using platform independent software like XML and JAVA that used to integrate qualitative spatial reasoning engines (SparQ) with GIS application. SparQ is set of modules that structured to provides different reasoning services. SparQ supports command line instructions and it has a specific syntax as set of commands. The developed API provides interface between GIS application and reasoning engine. It establishes connection with reasoner over TCP/IP, takes XML format queries as input from GIS application and converts into SparQ module specific syntax. Similarly it extracts given result, converts it into defined XML format and passes it to GIS application over the same TCP/IP connection.
The most challenging part of thesis was SparQ syntax analysis for inputs and their outputs. Each module in Sparq takes module specific query syntax and generates results in multiple syntaxes like; error, simple result and result with comments. Reasoner supports both binary and ternary calculi. The input query syntax for binary-calculi is different for ternary-calculi in the terms of constraint-networks. Based on analysis I, identified commonalities between input query syntaxes for both binary and ternary calculi and designed XML structures for them. Similarly I generalized SparQ results into five major categories and designed XML structures. For ternary-calculi, I considered constraint-reasoning module and their specific operations and designed XML structure for both of their inputs and outputs
Matching Qualitative Constraint Networks with Online Reinforcement Learning
No full textLocal Compatibility Matrices (LCMs) are mechanisms for computing heuristics for graph matching that are particularly suited for matching qualitative constraint networks enabling the transfer of qualitative spatial knowledge between qualitative reasoning systems or agents. A system of LCMs can be used during matching to compute a pre-move evaluation, which acts as a prior optimistic estimate of the value of matching a pair of nodes, and a post-move evaluation which adjusts the prior estimate in the direction of the true value upon completing the move. We present a metaheuristic method that uses reinforcement learning to improve the prior estimates based on the posterior evaluation. The learned values implicitly identify unprofitable regions of the search space. We also present data structures that allow a more compact implementation, limiting the space and time complexity of our algorithm.</jats:p
Combining DRA and CYC into a Network Friendly Calculus
No full textAbstract. Qualitative spatial reasoning is usually performed using spatial calculi specially designed to represent certain aspects of spatial knowledge. However most calculi must be adapted for use in applications where additional constraints are at play. This paper combines the DRA and CYC algebras into a new calculus for reasoning within network structures. In the process we prove some interesting results about some properties of the standard operations, converse and composition, for versions of CYC and DRA
A qualitive reasoning approach for improving query results for sketch based queries by topological analysis of spatial aggregation
No full textDissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Sketch-based spatial query systems provide an intuitive method of user interaction for
spatial databases. These systems must be capable of interpreting user sketches in a way
that matches the information that the user intended to provide. One challenge that must be
overcome is that humans always simplify the environments they have experienced and this
is reflected in the sketches they draw. One such simplification is manifested as aggregation
or combination of spatial objects into conceptually or spatially related groups.
In this thesis I develop a system that uses reasoning tools of the RCC-8 to evaluate sketchbased
queries and provide a method for minimizing the effects of aggregation by
determining whether a solution to a query can be expanded if some groups of regions are
assumed to be parts of a larger aggregate region. If such a group of regions is found, then
this group must be included in the solution. The solution is approximate because the
approach taken only verifies that assumed parts of an aggregate are not inconsistent with
the configuration of the whole solution. Only cases where the size of the solution equals the
size of the query minus one are analysed.
It is observed that correctly identifying aggregated regions leads to solutions that are more
similar to the original query sketch when the size of every other solution is smaller than the
size of the query or when a lower limit is placed on the acceptable size of a solution because
the new, expanded or refined solution becomes more complete with respect to the sketch
of the query
Modeling customary land tenure in relation to the national land administration model : case study of the northwest region of Cameroon
No full textDissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial TechnologiesLand administration systems all over the world are always preoccupied with the registration of land as it is one of the only ways to have legal ownership of property and do not ever address customary right to land on a full scale. The conventional land tenure systems in Cameroon have is not fully integrated and written in the official land administration system of the country. Cameroon comprises about 250 ethics different having different customary land tenure systems most of which have similar concepts and features. This thesis seeks to provide an overview of these standard systems and comparing it with the official land tenure system to understand where the systems counteract. The Northwest region of the country was chosen as a case study as it has a customary system that is like other ethnic groups in the country. The idea was to develop domain models for the two systems and propose ways by which the government can assimilate the customary system into the legal system.
This thesis describes the development as an ontology, and it represents the comparison between the two systems. The ontology approach was chosen as it efficiently models concepts related to land tenure that can be easily integrated into other systems for assimilations. The building of the customary land tenure system models based on ideas gotten from the concept of the Social Tenure Domain Model (STDM) as it gives the standards for modeling concepts based on epistemology and reality. The model was validated demonstrations of some instances related to data gotten from content analysis and was found to be valid
Dynamic programming for aligning sketch maps
No full textDissertation submitted in partial fulfilment of the requirements for the degree of Master of Science in Geospatial TechnologiesSketch maps play an important role in communicating spatial knowledge, particularly in applications interested in identifying correspondences to metric maps for land tenure in rural communities. The interpretation of a sketch map is linked to the users’ spatial reasoning and the number of features included. Additionally, in order to make use of the information provided by sketch maps, the integration with information systems is needed but is convoluted. The process of identifying which element in the base map is being represented in the sketch map involves the use of correct descriptors and structures to manage them. In the past years, different methods to give a solution to the sketch matching problem employs iterative methods using static scores to create a subset of correspondences. In this thesis, we propose an implementation for the automatic aligning of the sketch to metric maps, based on dynamic programming techniques from reinforcement learning. Our solution is distinctive from other approaches as it searches for pair equivalences by exploring the environment of the search space and learning from positive rewards derived from a custom scoring system. Scores are used to evaluate the likeliness of a candidate pair to belong to the final solution, and the results are back up in a state-value function to recover the best subset states and recovering the highest scored combinations. Reinforcement learning algorithms are dynamic and robust solutions for finding the best solution in an ample search space. The proposed workflow improves the outcoming spatial configuration for the aligned features compared to previous approaches, specifically the Tabu Search
Cognitively plausible representations for the alignment of sketch and geo-referenced maps
No full textIn many geo-spatial applications, freehand sketch maps are considered as an intuitive way to collect user-generated spatial information. The task of automatically mapping information from such hand-drawn sketch maps to geo-referenced maps is known as the alignment task. Researchers have proposed various qualitative representations to capture distorted and generalized spatial information in sketch maps, however thus far the effectiveness of these representations has not been evaluated in the context of an alignment task. This paper empirically evaluates a set of cognitively plausible representations for alignment using real sketch maps collected from two different study areas with the corresponding geo-referenced maps. Firstly, the representations are evaluated in a single-aspect alignment approach by demonstrating the alignment of maps for each individual sketch aspect. Secondly, representations are evaluated across multiple sketch aspects using more than one representation in the alignment task. The evaluations demonstrated the suitability of the chosen representation for aligning user-generated content with geo-referenced maps in a real-world scenario
