1. Introduction
Remote sensing (RS) image analysis plays a crucial role in various applications that include land cover mapping, urban planning, and environmental monitoring [
1]. Remote sensing image scene detection and classification involve identifying and categorizing different land cover types and urban features from satellite images [
2]. In urban landscapes, these tasks are crucial for land management, resource monitoring, and sustainable development. Recently, various methods have been used for object detection and scene classification from remotely sensed satellite images. However, traditional methods for scene detection and classification, which rely on manual feature extraction and handcrafted algorithms, are often unable to accurately capture the complex spatial and spectral patterns in remotely sensed data due to their lack of accuracy and scalability [
3]. Whereas state-of-the-art deep learning techniques have lately shown significant potential and improvements in automatically learning relevant features for efficient scene detection and classification, they are limited in accurate recognition, interpretability, and semantic analysis of the objects and scenes detected [
4,
5]. This is due to the composition of RS images, which include complex urban objects that vary in geometrical shapes, functional structures, environmental contexts, and semantic heterogeneity.
Deep learning models, such as convolutional neural networks (CNNs), have demonstrated exceptional performance in various computer vision tasks, including image classification and object detection [
6]. In remote sensing image analysis, deep learning models have been employed to learn complex spatial and spectral patterns from large-scale datasets [
7]. These models automatically extract hierarchical representations, allowing for more effective scene detection and classification. The methods have been used for automatic analysis of complex images to identify and classify disaster management, planning, and mitigation for their relevant object contents [
8]. For example, a CNN-LSTM model combination was proposed by Husni et al. [
9] for identifying littering behavior in smart environments. A tiny garden and a river location were used to evaluate the proposed method. A model was also used to evaluate the flood risk of some bounded metropolitan areas using geospatial data from publicly accessible databases [
10]. Vehicle detection in a variety of environments was assessed by Shokri et al. [
11] using object detection-based deep learning methods. Nadeem et al. [
12] developed FlameNet, a CNN-based system, for fire detection in a smart city setting. The network was built with the ability to detect fires and send an alarm to the relevant agency. An explainable AI was utilized by Thakker et al. [
13] as a hybrid classifier for object detection and categorization of images with the presence of flooding by fusing deep learning and semantic web technologies. The system offered flexibility in classifying images and detecting objects using their coverage connections and expert knowledge. Cong et al. [
14] performed a precision analysis of geotechnical investigations and urban planning by combining smart sensing technology with a predictive analytics method utilizing Kriging and ensemble learning. Lastly, Chen et al. [
15] designed a decoder network for the semantic segmentation of the Adverse Conditions Dataset collected with Correspondences (ACDC) using images obtained in various smart city environments at different times and locations.
The development of knowledge-driven approaches that incorporate remote sensing image analysis with expert knowledge from environmental scientists for effective interpretation of the images has been identified as an important direction in data-driven research [
16]. In recent years, the integration of ontology-based techniques with machine learning algorithms has shown promising results in semantic understanding of scene detection and object classification tasks [
17,
18]. Ontology provides a formal representation of knowledge in a domain, enabling semantic understanding and reasoning. Applying ontology in remote sensing image analysis is important in capturing essential knowledge such as spatial relationships and semantic hierarchies in land cover classes [
19]. This enhances automatic semantic analysis to aid in more interpretable scene detection and classification. Combining deep learning’s ability to learn complex patterns and ontologies’ contextual understanding will enhance the effectiveness of scene detection and classification tasks and ultimately achieve robust land cover mapping, urban planning, environmental monitoring, and contribute to sustainable development and resource management [
20,
21]. Hence, ontology-based deep learning offers a promising approach for remote sensing image scene detection and classification. Integrating ontology with deep learning models by effectively incorporating semantic knowledge into the image analysis process has led to improved accuracy and interpretability [
22].
Despite the potential benefits of ontology-based deep learning, several challenges exist. Constructing and maintaining ontology for remote sensing image analysis can be complex and time-consuming [
23]. Additionally, the semantic gap between the ontology and the deep learning models poses a challenge in their effective integration. Bridging this gap requires careful ontology design and alignment with the deep learning architecture [
23]. Nevertheless, the integration of ontology-based techniques with deep learning opens up exciting opportunities. This study aims to achieve fine-grained objects detection and scene classification, improved interpretability, and ultimately contribute to more accurate land cover mapping, urban planning, and environmental monitoring for disaster planning. This study presents an ontology-based deep learning framework that combines a deep learning algorithm and ontology for automatic detection and classification of objects in remotely sensed satellite images and performs knowledge extraction and modeling of the scene classification outcomes. By combining the semantic knowledge from ontology with the representation and prediction capabilities of deep learning models, more interpretable scene detection and classification can be achieved. The proposed model employs an efficient computer vision algorithm for object detection from remotely sensed satellite images captured from the Kwazulu-Natal province, South Africa. This is combined with an ontology model for semantic reasoning of detected objects in the scenes. The ontology provides a framework for capturing domain-specific knowledge, improving the understanding of remote sensing images, and enhancing the interpretability of deep learning models.
The main contributions of this study include:
Modeling a lightweight YOLOv8-based algorithm for object detection and scene classification in remotely sensed satellite images.
Proposing a mathematical and ontological model for establishing knowledge taxonomy, knowledge extraction, and inferences.
Creating SPARQL database for knowledge inferences and validation of the ontological reasoning. The SPARQL database is made publicly available by the authors, as shared in the Data Availability Statement, at:
https://data.mendeley.com/datasets/s5v4zz7yj5/1 (accessed on 1 June 2024).
The remaining part of this work is organized as follows:
Section 2 discusses a review of related works.
Section 3 describes the research methodology and ontology modeling.
Section 4 discusses the results, summary and future works. This paper is concluded in
Section 5.
2. Review of Related Works
This section highlights various approaches used in integrating ontology-based frameworks with image analysis for knowledge representation and inferences. This has gained attention in recent years, with machine learning models incorporating ontological modeling in the image analysis process. An image classification process was modeled using ontology to represent decision tree-based classifiers and rule-based expert systems to provide a data-sharing mechanism with applications working on oceanic images [
24]. Alirezaie et al. [
25] developed an ontology framework, SemCityMap, for satellite image classification. The framework incorporated semantic information about mapping locations and paths for the provision of a knowledge representation and reasoning methods to achieve high-level querying. Also, image classification based on ontology and a hierarchical max-pooling (HMAX) model that utilized merged classifiers was proposed by Filali et al. [
26]. Ontological relationships between image categories that were in line with training visual feature classifiers were derived by merging the outputs of hypernym–hyponym classifiers for better discrimination of the classes detected. Wang et al. [
27] also developed an ontology-based framework for integrating remotely sensed imagery, image products, and in situ observations. The system combined remote sensing imagery with semantic queries based on a description logics (DL) query and SPARQL.
A deep learning algorithm integrated with ontology models was employed by Fang et al. [
28] to develop a knowledge graph that can recognize falling from height (FFH) hazards. The ontological model employed knowledge extraction and knowledge inference based on image analysis and classification for hazard prediction. Miranda et al. [
29] also proposed an ontology-based deep learning framework for land cover classification. They used a semantic reasoning approach in a medium-resolution optical imagery document containing features such as the normalized difference vegetation index, brightness, gray level co-occurrence matrix homogeneity, and rectangular fit from Indonesia National standard RSNI-1 Land Cover satellite imagery. They demonstrated that incorporating the semantic information from the ontology improved the classification accuracy of Sentinel-2 satellite imagery. Xie et al. [
22] presented an ontology-based methodology framework for enabling object recognition using rules extracted from high-level semantics. The framework was able to semantically organize the descriptions and definitions of objects using RDF-triple semantic rules from the developed domain ontology. Low-level data features defined from optical satellite and LiDAR images were mapped to the decomposed parts of the RDF-triple rules, and a probabilistic belief network (PBN) was used to represent the relationships between low-level data features and high-level semantics.
Sambandam et al. [
30] also used a semantic web technology to establish the spatial ontology for risk knowledge in spatial datasets. The model was integrated with deep attention-based bidirectional search and rescue long short-term memory for efficient image analysis. The system was experimented on using the University of California Merced (UCM) dataset, with an overall accuracy (OA) of 92.3%. Also, an ontology-driven hierarchical sparse representation for hierarchical learning for large-scale image classification was developed [
31]. The system used WordNet to construct semantic ontology in the form of a visual ontology tree based on deep features extracted by Inception V3. An algorithm based on split Bregman iteration was developed to learn hierarchical sparse representation and was evaluated using three benchmark datasets: ILSVRC2010, SUN397, and Caltech256.
Benkirane et al. [
32] proposed an ontology model in a deep learning context for representing urban environments using a structured set of concepts connected by semantic relationships. The ontology model was used to extract monocular cue information from images, which was sent, together with the images, to a deep neural network model for knowledge inferential analysis. The system was experimented on using benchmark datasets: KITTI, CityScapes, and AppolloScape. A deep learning-based ontology model was used to generate a set of features trained using ontology for the image classification process [
33]. In the system, an ontological bagging algorithm was integrated with an ensemble technique of convolutional neural network (CNN) models to improve forest image classification accuracy. The ensemble technique, which was composed of ResNet50, VGG16, and Xception, achieved a 96% accuracy and 53.2% root mean square error when experimenting on the forest dataset. An ontology-guided deep learning approach for urban land use classification was proposed by Li et al. [
18] using a combination of a collaboratively boosting framework (CBF) with a data-driven deep learning module and a knowledge-guided ontology reasoning module. The ontology reasoning module was composed of both intra- and extra-taxonomy reasoning models for correcting misclassifications and generating inferred channels to improve the discriminative performance of DSSN in the original remote sensing (RS) image space. The system was experimented on using two publicly open RS datasets: UCM and ISPRS Potsdam. Gupta et al. [
34] developed an algorithm that combined CNN and ontology for inferring abstract patterns in Indian monument images. A transfer learning-based approach was used, in which domain knowledge was transferred to a CNN during training via top-down transfer and inference was made using CNN prediction and an ontology tree via bottom-up transfer. Kim et al. [
35] developed a scene graph generation method based on the RDF model to establish semantic relations in images. Deep learning models were used to generate scene graphs expressed in a controlled vocabulary, improving the understanding of relations between image objects.
A lightweight CNN model based on a deep neural network was employed in an object detection process for surface scratch detection [
36]. Fundamental semantic sensor network (SSN) ontologies for a fire prediction and management system were proposed by Chandra et al. [
37]. Information on several meteorological conditions, such as temperature, relative humidity, and wind speed, was gathered using the semantic sensor networks. In order to calculate fire weather indices, the system used ontology rules, which SPARQL then translated into a resource description framework (RDF). Li et al. [
38] proposed a framework that integrates computer vision, ontology, and natural language processing for enhancing systematic safety management for hazard avoidance and elimination. Patel et al. [
39] developed a system for locating concealed, abandoned bags in public areas. The system identified and predicted various interactions between the items in images using computer vision-based visual connection identification. Salient information in video footage was extracted and represented as a knowledge graph using the suggested ontology-based method. Using SPARQL queries, the unexpected events were found based on the knowledge retrieved. The ABODA Dataset, AVSS 2007, PETS 2006, and PETS 2007 were used for testing the propose system. A strategy to boost confidence in machine learning models used in safety-critical domains was proposed by Lynn et al. [
40]. The resilience and completeness of the model’s training dataset were guaranteed by the system’s design. The proposed approach used a combination of domain ontology and characteristic ontologies for image quality to validate the training dataset in terms of image quality and domain completeness. A scene graph engineering and reasoning method based on ontology was presented to explain the structural links derived from retrieved objects by Raj et al. [
41]. The ontological model in the proposed system produced associated entities and relationships from objects detected using YOLO. The system used the semantic web rule language (SWRL) to find the image sequence for the structural link.
Lastly, it can be concluded from this review that limited works have been performed regarding the integration of the ontology model with state-of-the-art deep learning methods for the analysis of complex urban objects with functional structures and environmental contexts. Traditional machine learning image analysis algorithms have shown some weaknesses in the detection and classification of objects in complex images [
42,
43] such as remotely sensed satellite images. In fact, the traditional feature extraction methods in complex images do not capture the semantic relationships between the objects contained in the images, making it difficult to represent semantic knowledge in images with ontology. The application of deep learning-based approaches integrated with ontology modeling has been limited to image classification tasks. To the best of our knowledge, ontology modeling has been rarely applied to semantic analysis of deep learning-based object detection model outputs from remote-sensing satellite images for the prevention of disaster. This study therefore explores the possibility of utilizing ontology for the semantic analysis of deep learning-based object detection outputs. Some ontology frameworks and their limitations are summarized in
Table 1.
4. Results and Discussion
In this section, an analysis of the results of the proposed model is carried out. The performance of the deep learning model is first evaluated using appropriate metrics, such as accuracy, precision, and recall. Sample results of the object detection deep learning model are presented in
Figure 5. The results are then analyzed by incorporating feedback into the ontology model for semantic analysis and insights. The ontological reasoning module is composed of a reasoning function that provides further interpretation and analysis of the classification results of the deep learning module based on the ontological reasoning rules. The reasoning function aims to generate inferred information from the taxonomy set and to improve the understanding and enhance the interpretability of the object detection deep learning model output.
4.1. Evaluation Metrics
The deep learning-based object detection techniques were assessed using the proposed dataset. Five metrics, detection accuracy (DA), recall (R), precision (P), average precision (AP), and mean average precision (mAP), were used to analyze the models. Here is a definition of these metrics:
Detection accuracy: The degree to which a model can accurately identify objects in an image is measured by its detection accuracy. Precision, recall, and F1-score are also measures used to assess a model’s detection performance.
Precision is the percentage of all objects detected by the model that are true positives. With a high precision, the model is less likely to produce false positives, which means that most of the objects it detects are real.
The average precision of the objects detected by the model is defined as the average precision (AP).
The overall mean value of the AP is defined as the mean average precision (mAP).
Recall estimates the percentage of actual objects in the image that the model correctly identified out of all the false positives. A high recall means that the model can successfully identify the majority of the image’s objects.
Ontology metrics:
We have also used some metrics to define both the complexity measures and the response time of the proposed ontology model. These metrics are used to quantify the overall design complexity of the ontology and directly infer the reasoning performance using the model’s internal structure, among other things. Three primary factors [
51] have been considered in the selection of the measures. These include the following:
Class count: This is the total number of classes in the ontology. It typically provides information on the intricacy and scope of the study’s domain covering.
Class depth: This indicates the degree and depth of hierarchy of the classes and subclasses used in the research.
Class breadth: This indicates how many subclasses there are on average within a class. It is sometimes referred to as the ontology’s branching factor.
The more resources needed to analyze, comprehend, and maintain the ontology, the more complicated the model is, as shown by the greater metric value. As a result, four measures [
52] have been chosen to assess the suggested ontology’s design complexity. These include the following:
Number of children (NOC): In the ontological inheritance hierarchy, the NOC represents the total number of its direct offspring. The number of subclasses that are directly derived from a particular class is known as its NOC.
Depth of inheritance (DIT): In an ontological inheritance hierarchy, DIT is the length of the longest path from a particular class to the root class.
Class in-degree (CID): In an ontology graph, CID counts the number of edges that point to a node for a given class.
Class out-degree (CID): Regarding the COD, COD measures the number of edges leaving a given class in the ontology graph.
Reasoning performance: The reasoning performance [
53] of the ontology geographical database used in this study in terms of reasoning time and reaction time has been taken into consideration in order to further assess the effectiveness of the suggested ontology:
Reasoning time: This is the amount of time needed for the reasoning engines used in this study to validate the ontology or infer knowledge.
Query response time: This gauges how long it typically takes to respond to a given query.
4.2. Class-Wise Detection Performance
The object detection model identified five objects: residences, roads, shorelines, swimming pools, and vegetation from the proposed remotely sensed satellite images dataset. The class-wise detection performance of each of these objects in
Table 2 shows that swimming pools were detected with the highest precision score of 62.7%, followed by the vegetation, with a precision score of 57.3%, and shorelines, with a precision score of 54.6%.
Both the residence and roads had comparable detection rates, with residence scoring 41.1 percent, 42.1 percent, 19.3 percent, and 12.8 percent for precision, recall, mAP50, and mAP (50–95), respectively. The roads scored 41.2 percent, 57.1 percent, 13.7 percent, and 4.75 percent for the same metrics. This similarity in detection rates of the objects shows that the objects are evenly distributed within the satellite images captured in the same areas. There are, however, instances of higher detection rates for shorelines, swimming pools, and vegetation in areas where they are densely distributed, as presented in
Figure 5a–c. More detection results are presented in
Appendix A.
In
Table 3, the performance of the model is compared with some object detection models using precision, recall, mAP50, MAP50-95, and speed.
Based on the results in
Table 3,
Table 4,
Table 5 and
Table 6, the proposed YOLOv8 model has been proven to outperform other object detector methods. This has been established through the following:
YOLO v8 achieved a very high speed in detecting objects, with the lowest latency rate, as presented in
Table 3.
The performance of YOLOv8 in terms of precision and recall, especially when considering speed, is better than the other objects detectors and more reliable, as presented in
Table 3.
In
Table 4, it performs better when compared with some state-of-the-art methods in mAP when experimented on using the publicly available datasets Visdrone and PascalVOC.
The F1 score and IOU in
Table 5 show that the model achieves more that 50% accuracy in detecting most of the objects.
The confusion matrix in
Table 6 also shows that the model is able to achieve a high detection rate for most of the objects correctly.
4.3. Ontology Model Analysis
In analyzing the proposed ontology model, we used the earlier defined ontology metrics. The NOC value for the scene class is 3 and for the area class is 4 for the ontology that is explained in
Section 3. As the NOC value increases, so does the complexity. A higher NOC number also suggests that more subclasses might be impacted by changes made to this class, necessitating more resources in the maintenance of the subclasses. Furthermore, the DIT value for the scene class is 3 and the DIT for the area class is 2, while the DITs for the vegetation area, water area, residential area and way area classes are 1 each for the ontology outlined in
Section 3. A higher DIT value indicates that the class reuses more information from its predecessors and is located further down the inheritance tree. A higher DIT value also suggests that the class is more likely to be impacted by modifications in any of its ancestors, making it more challenging to maintain. The class hierarchy is in a top-down, depth-first fashion, beginning at the root node in the DIT calculation.
Additionally, the CID values for the scene class and area class in the proposed ontology are 3 and 4, respectively. The value of class-in-degree indicates how other nodes are using a certain class. The greater the number of nodes that depend on a certain CID, the higher the value of CID will be. The CID value for the water area class is 5, vegetation area is 3, way area is 4, and residential area is 4. Lastly, the proposed ontology has a COD value of 1 for the vegetation area class and a COD value of 3 for the residential area. The number of nodes that a certain class refers to is indicated by the value of out-degree. In conclusion, this analysis presents a less complex ontology with the maximum DIT of 3 and NOC of 4 in the whole ontology proposed, making it scalable. This will directly affect the reasoning performance in terms of reasoning time and query response time. The output indicates quick reasoning and response time with low computational resources for processing.
4.4. Semantic Reasoning and Event Inferences
The semantic reasoning modules aim to generate inferred information from the taxonomy set based on the ontological reasoning rules. The reasoning rules are established following these logical semantics:
The symmetric rule stating that if a source instance is related to a target instance, then the target must also be related to the source.
The transitive rule states that if instance A is related to instance B, and instance B is related to instance C, then A is also related to C.
For instance, let RA be a selected area. The RA area contains all the regions located within the description represented in Equation (
24) at the given point. For example, according to the given query, these selected regions are assumed to be residential areas caught in between water areas and way areas during heavy raining events.
is a subclass of residential area in way area, and
represents a subclass of residential area in the water area, while
S represents the spatial relation (a subclass of the property isAdjacentTo) of the part of
represented by
and the part of
represented by
caught during the event. The query therefore returns the areas that can be influenced by the closeness of the detected objects in the scene captured.
4.4.1. Ontology Reasoning and Inferences
Three inferential instances drawn from the area class are represented diagrammatically in
Figure 6a–c. In
Figure 6a, the area class has two subclasses, water area and residential area, whose subclasses swimming pools and low-rise buildings are related through the property
hasSwimmingPools. The relations between the concepts are provided via two properties;
hasSubclass and
hasSwimmingPools. Also in
Figure 6b, the Area class has two subclasses VegetationArea and ResidentialArea whose subclasses Forest and LowRisingBuilding are related through the property
isAdjacentTo. The relations between the concepts are provided via two properties;
hasSubclass and
isAdjacentTo. For the
Figure 6c, the Area class has two subclasses WayArea and WaterArea whose subclasses Freeway and Shoreline are related through the property
isAdjacentTo. The relations between the concepts are provided via two properties;
hasSubclass and
isAdjacentTo.
Using SPARQL queries for drawing inferences around the objects in the neighborhood, the outcomes are presented in
Figure 7a–c. For example, it can be inferred from
Figure 7a that there are some low-rise buildings containing pools, which may be areas of concern. Also,
Figure 7b suggests that some low-rise buildings are adjacent to the forest vegetation type. The outcome from the SPARQL query presents shorelines and freeways, as shown in
Figure 7c.
4.4.2. Visualization Analysis of Detection Results Output
This section presents the visual analysis of the object detection outcomes using the knowledge representation model. In
Figure 8a, the objects detected include roads, residences, and vegetation. The detection accuracy of the vegetation is 59%, residences have a detection accuracy of 41%, and roads have a detection accuracy of 51%. This is visualized in
Figure 8b, with relations identified including residences adjacent to vegetation, vegetation with a subclass of forest, and way area with a subclass of roads.
In
Figure 9a, the objects detected include residence, roads, swimming pools, and vegetation. Swimming pools had the highest detection accuracy of 68%, with residences having 42% and vegetation having 44%. The knowledge representation of the scene is presented in
Figure 9b. The relations established include
isadjacentTo and
hasSwimmingPools. It can be inferred that most of the residences captured had swimming pools with some degree of adjacency to the forest, as shown in
Figure 10a. The advanced visualization in
Figure 10b shows the presence of a vegetation area, residential area, water area, and way area as the outcomes of the SPARQL query. This also establishes that the residential area was adjacent to the vegetation area and way area with the presence of swimming pools. The
Figure 8 output is also further expatiated in
Figure 10a using the SPARQL query showing the presence of the vegetation area, residential area, and way area. Relations such as
isAdacentTo between the subclasses of forests and residences as well as residences and roads are also presented. This outcome presents a more secured area with the presence of the forest.
In
Figure 11a, the objects detected include roads, swimming pools, residences, vegetation, and shorelines. The detection accuracy of vegetation is 59%, while shorelines have high detection accuracy of 60%, residences have a detection accuracy of 51%, and swimming pools have a detection accuracy of 59%. The ontology description presented in
Figure 11b shows the relations identified, including residences with swimming pools, roads adjacent to shorelines, and residences adjacent to vegetation. The presence of shorelines and some residences is conspicuous. Based on the SPARQL query, detailed ontology description of scene classification is produced in
Figure 12, showing the presence of vegetation areas, residential areas, water areas, and way areas. It also reveals the presence of shorelines and swimming pools in the water area. The outcome in
Figure 12 validates the presence of water areas adjacent to way areas and to residential areas. The result presents a more sensitive location.
4.5. Ontology Modeling—A Case Study of Flood Prevention
Adapting this model specifically to flood prevention, for instance, will lead to providing further queries that can be implemented in the case study. Various instances are highlighted below:
If a residence is located adjacent to a road, and both the residence and road are affected by flooding, then the residence is at a high risk of flooding. This rule states that if a residence is adjacent to a local road and both the residence and the road are affected by flooding, then the residence is considered to be at a high risk of flooding. The variables “?residence” and “?road” represent the residence and road individuals, respectively. The predicates “Adjacent”, “AffectedByFlooding”, and “HighRiskOfFlooding” represent the relationships between the entities. This rule can be expressed in SWRL [
62] as follows:
If a swimming pool is in a residence, and its drainage system impacts the surrounding area, then it is at high risk of flooding. This rule has the following three conditions: 1. LocatedIn(?swimmingPool, ?residence): The swimming pool is located in a residence. Here, ?swimmingPool represents the individual swimming pool, and ?residence represents the individual residence. 2. ImpactsSurroundingArea(?drainageSystem drainageSystem): The drainage system of the swimming pool has an impact on the surrounding area. ?drainageSystem represents the individual drainage system. The SWRL formulation of this rule is given below.
If vegetation is located on a shoreline, it can help prevent erosion and absorb water. This rule declares that if vegetation is located on a shoreline then it can prevent erosion and absorb water. The variables “?vegetation” and “?shoreline” represent the individual vegetation and shorelines, respectively. The predicates “LocatedOn”, “CanPreventErosion”, and “CanAbsorbWater” represent the relationships and properties between the entities. This rule can be expressed in SWRL as follows:
If a residence is in a low-lying area, then it is at a high risk of flooding. This rule states that if a residence is located in a low-lying area, which is identified by the predicate “LowLyingArea”, then the residence is considered to be at a high risk of flooding. The variables “?residence” and “?lowLyingArea” represent the individual residences and low-lying aresa, respectively. The predicate “HighRiskOfFlooding” represents the relationship indicating that the residence is at a high risk of flooding. The SWRL representation of this rule is given below.
If a swimming pool is located uphill from a residence, then it can increase the risk of flooding for the residence by contributing to runoff. This rule states that if a swimming pool is located uphill from a residence and it contributes to runoff, then the residence is considered to be at an increased risk of flooding. The variables “?swimmingPool” and “?residence” represent the swimming pool and residence individuals, respectively. The predicate “LocatedUphill” represents the relationship indicating that the swimming pool is located uphill from the residence. The predicate “ContributesToRunoff” represents the relationship indicating that the swimming pool contributes to runoff. The predicate “IncreasedRiskOfFlooding” represents the relationship indicating that the residence is at an increased risk of flooding. This rule can be represented in SWRL as follows:
If a road is adjacent to the residence and located in a floodplain, then it is at high risk of flooding. This rule states that if a road is adjacent to a residence and located in a floodplain, then the road is considered to be at a high risk of flooding. The variables “?road” and “?residence” represent the road and residence individuals, respectively. The predicate “Adjacent” represents the relationship indicating that the road is adjacent to the residence. The predicate “LocatedInFloodplain” represents the relationship indicating that the road is located in a floodplain. The predicate “HighRiskOfFlooding” represents the relationship indicating that the road is at a high risk of flooding. The SWRL representation of this rule is given below.
If vegetation is adjacent to the residence, then it can help to absorb rainfall and prevent runoff. This rule states that if vegetation is adjacent to a residence, then it is considered to help absorb rainfall and prevent runoff. The variables “?vegetation” and “?residence” represent the vegetation and residence individuals, respectively. The predicates “Adjacent”, “HelpsAbsorbRainfall”, and “HelpsPreventRunoff” represent the relationships and properties between the entities. This rule can be expressed in SWRL as follows:
If a shoreline lacks vegetation, then it is at a high risk of flooding due to storm surges or high tides. This rule states that if a shoreline lacks vegetation, it is considered to be at a high risk of flooding from storm surges or high tides. The variable “?shoreline” represents the individual shoreline. The predicate “LacksVegetation” represents the property indicating that the shoreline lacks vegetation. The predicate “HighRiskOfFlooding” indicates that the shoreline is at a high risk of flooding. The SWRL representation of this rule is given below.
4.6. Ontology Model Justification
The incorporation of ontology into deep learning models for object recognition and image classification in the context of smart cities presents several benefits with regard to overall system performance, scalability, interpretability of the models, semantic comprehension, and data integration. These advantages support the use of ontology-based techniques in creating reliable and successful smart city applications in the following areas:
Contextual awareness: The proposed model is able to comprehend the context and semantics of objects inside the smart city environment because the ontologies offer an organized framework for defining and relating concepts.
Expandable and scalable knowledge structure: As smart cities develop, the proposed ontology provides a scalable structure to embrace new ideas and connections.
Adaptability to new situations: The model’s easy extension and adaption to new situations and applications within the context of smart cities is made possible by the structured knowledge representation found in the ontologies.