Data:ArcGIS-CyberGIS-Chaining

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  • Motivation
  • Background
  • Use cases
    • Two use cases are under consideration to show the benefits of integrating ArcGIS Online and CyberGIS Gateway and to identify and resolve the barriers to such integration. The first use case focuses on finding an optimal assignment of crop types to available land parcels in such a way that maximizes the potential yield. The second use case concerns the mapping of flows of Twitter population at a certain level of administrative units.
    • Optimizing the use of crop lands is a critical concern for farmers and agriculture-dominant local areas. Systematic plans for cropland use may be planned in advance by considering various factors that influence the potential yield and production cost at land parcels. While such factors would be numerous, the characteristics of land and crop would play an important role in the optimal use of the land. This study considers the current landcover, soil type, and accessibility to food processing centers of land parcels in order to determine an optimal assignment of crop types to land parcels. The accessibility to food processing centers is a factor that affects the production cost of crops. For simplicity, the study assumes that the transportation cost of crop yields would vary according to whether or not the land parcels reside in the service area of food processing centers. This service area can be defined by an analyst by defining a threshold drive time to which the food processing centers apply a flat freight rate. The current landcover and soil type of land parcels impact the potential yield, together with multiple properties of crops such as price and capacity (?).
    • The cropland use case will be implemented by chaining multiple web services for geoprocessing and optimization. Given the data of food processing centers, land parcels, and crop properties and a parameter of drive time, the service area of food processing centers will be first determined from ArcGIS Online Service Area Service. Then, land parcels and the service area are intersected to decide the transportation cost for each land parcels. Next, crop types will be assigned to the land parcels via the Assignment Optimization service hosted by CyberGIS Gateway. The optimization results are then published to either ArcGIS Online or CyberGIS Gateway according to user preference. Figure 1 shows the workflow for the cropland use case.

CroplandUseOptimizationSimple.png

    • Social media data have been increasingly used to understand various dimensions of human behaviors. Georeferenced data from social media are particularly useful for understanding spatial footprints of individuals' daily interests and activities. This study allows the user to examine one such a footprint by using tweets data available from the Twitter service. In particular, it derives from geotagged tweets a movement trajectory for each Twitter user and identifies flows across certain aggregate units. The resultant OD table of Twitter users' movements are visualized as an all-to-all flow map. This kind of geovisualization allows researchers in social sciences to easily understand spatial patterns in the movements of Twitter population. As in the case of the cropland use case, the flow mapping of Twitter users is enabled through a workflow-based service chaining across ArcGIS Online and CyberGIS Gateway.

MappingFlowsOfTweetPaths.png

    • As illustrated in Figure 2, a reverse geocoding procedure is applied to geotagged tweets generated from the U.S. This step is necessary to facilitate the identification of flows crossing two different aggregation units and is enabled by ArcGIS Online Geocoding Service. Movements of each Twitter user across two different aggregation units are then determined through a Flow Detection Service from CyberGIS Gateway. The consequent OD table of the movements are used as an input for the Flow Mapping Service, along with the boundaries or centroids of the aggregation units. This service is also provided by CyberGIS Gateway. The final output of the workflow is a flow map of Twitter population.
  • Feasibility Analysis for Cropland Optimization
    • Step 1. Access to ArcGIS Online and CyberGIS Open Service API
      • A CyberGIS user obtains a open service token as he/she signs in the CyberGIS Gateway.
      • A CyberGIS user needs to provide his/her credentials for ArcGIS online at the front-end user interface for input data setup and backend service chaining.
      • Both tokens for ArcGIS Online and open service API should be cached.
      • Issue to solve: how to safely handle ArcGIS Online user credentials
    • Step 2. Input data setup
      • Locations of food processing centers
        • Four options are possible: i) user selection, ii) an ArcGIS service endpoint that returns ArcGIS JSON features, iii) user-uploaded data file, iv) an OGC service endpoint
      • Land parcels
        • Three options are possible: i) an ArcGIS service endpoint that returns ArcGIS JSON features, iii) user-uploaded data file, iv) an OGC service endpoint
      • Issues to deal with: for the cases of user-uploaded files and OGC service endpoints, intermediate tools are needed to transform standard feature data to ArcGIS JSON features and convert spatial reference information from OGC-based ones to Esri wkid.
    • Step 3. Service area determination
      • Asynchronous jobs need to be used, and the status of those jobs needs to be polled regularly.
      • Issues to deal with: job failures
    • Step 4. Intersection check and field calculator
      • The status of jobs needs to be polled regularly.
      • Issues to deal with: job failures, output data retrieval/transmission/management
    • Step 5. Assignment optimization
      • The status of jobs needs to be polled regularly.
      • Issues to deal with: if this service accepts land parcels in a standard GIS data format (e.g., shape files, WKT), land parcels need to be converted from ArcGIS JSON features to the standard format along with its spatial reference system. Also, if this service has a limit on data size, this should be also accounted for.
    • Step 6. Output publication as services
      • According to user preference, the outputs can be published to ArcGIS Online.
      • Issues to deal with: data size limits for data to be published as a hosted feature service.