The Multiple Criteria Decision Analysis
The multiple-criteria decision analysis tool (MCDA) is a new inclusion to the portfolio of the decision support system. It intends to empower the decision-maker with objective evaluation of different DRR options. The MCDA will enable the user to set up their own evaluation criteria’s, visualise various options for interventions based on those, and assess the best possible action.
For example, you may be researching a site for relocate people and need to figure out which sites would be suitable based on elevation, slope, and proximity to roads. This can be a time-consuming process with conventional desktop GIS tools. MCDA is a web-based application that makes the entire process more efficient. It allows you to use raster services to visualize information via web browser.
The MCDA tool uses fast, web-based weighted raster overlay to generate models from a service. Choose layers, assign weights, and adjust layer classification values to define your analysis. Then, run the modeler, and visualize results.
Understand weighted overlay
Weighted overlay has three conceptual steps. First, each raster layer is assigned a weight, as a percentage, in the analysis. This allows you to emphasize the relative importance of each layer in the analysis. Second, values within each raster layer are mapped to a common suitability scale. This allows you to compare the different types of information in each raster layer. Third, all raster layers in the analysis are overlaid. Each raster cell’s suitability value is multiplied by its layer weight and totalled with the values of other raster cells it overlays. The result is a suitability value that is used for symbology in the output raster layer.
In the illustration, the two input rasters have been reclassified to a suitability scale of 1 to 3. Each raster is weighted with a percent influence. The cell values are multiplied by their weight, and the results are added together to create the output raster. For example, in the upper-left cell, the values for the two inputs become (2 * 0.75) = 1.5 and (3 * 0.25) = 0.75. The sum of 1.5 and 0.75 is 2.25. The final value is rounded to 2 as the output is an integer raster layer.
Use your data in weighted overlay
UNOSAT hosts and maintains weighted overlay services that represent physiographic and ecological data. You can use these services in MCDA application to identify locations based on your criteria and answer geographic questions.
However, you may want to perform analysis using datasets that represent different criteria. You can host its own data on ArcGIS Enterprise in a weighted overlay service. You can then consume that service in MCDA application. This would allow you to share your data and analysis tools in the application.
For more information see Configuration overview. The document introduces the concepts you'll need to understand to set up your own weighted overlay service. Then, you can access this service in MCDA application.
Configuring the application to work with your data
The MCDA application is developed using ArcGIS Web AppBuilder (Developer Edition) and Suitability Modeler widget. By default, the MCDA application creates models using a subset of the raster MCDA Layers hosted by UNOSAT. In order to configure it to work with your own data, you will have to follow the steps outlined in this document.
Once you have an image service that exposes the weighted overlay functions, you will have to modify some of the configuration settings in before deploying the application.
The following settings must be modified:
- Go to application folder: <<your web server path>>\DSS\FJI\MCDA\app\configs\SuitabilityModeler\config_widgets_SuitabilityModeler_Widget_31.json
- Open the json file in a text editor and edit the following parameters:
- Set imageServiceUrl to the URL of the image service published in the previous step.
In addition, you may need to change the following settings:
- Go to application folder: <<your web server path>>\DSS\FJI\MCDA\app\config.json
- Open the json file in a text editor and edit the following parameters:
- Set portalURL to the URL of your ArcGIS Online organisation or your portal if you are not using ArcGIS Online.
- Find your web map id, navigate to ArcGIS Online or your Portal, and find the map you want to display. If it is one of your maps, make sure it's shared with everyone (public). View the map details and copy the ID from the URL in the top of your browser. The section you need to copy is bolded in the following URL: arcgis.com/home/webmap/viewer.html?webmap=7b099edb4f024aa7a4a6328bf010d06f.
Follow your web server's instructions to publish the contents of application folder as a web site or virtual directory.
For more information, see