ArcGIS Tutorial: Evaluate the steam pipe explosion in the urban environment

　　Overview

A 24 inch underground steam pipe exploded at a busy intersection in downtown Manhattan, New York on 2007. The explosion formed 40 floors of mud rain, scattered debris, and steam clouds higher than the Chrysler tower. Pipes are enclosed in asbestos (a carcinogenic substance) casings, so the accident location is classified as "asbestos contaminated area ". Explosion is likely to cause broken windows and sealing damage to the windows, resulting in pollutants entering the room. The following problem arises: Based on the set explosion distance, which buildings in the region need to be sampled. The geographic processing tool for 3D intersection setting operators can solve this problem.

This Guide uses arcscene to demonstrate how to prepare data and perform analysis using the 3D setup operator geographic processing tool to identify threats caused by pollutants in steam pipes. You will create a polygon element representing each building and intersection it with the affected area. The same workflow applies to arcglobe.

　　3D operators and closed polygons

To effectively use the 3D intersection geographic processing tool, your input element must be a closed polygon. A closed polygon is a set of triangles and rings used to define the volume of a single space. It should be regarded as closed, and the shell of the volume cannot have spacing between triangles or rings. In addition, no triangle or ring involved in defining the volume cannot overlap or overlap. If a building is created using a 3D layer-to-element type geographic processing tool by converting a drawn building outline to a polygon element, your elements are closed.

If a building is created by converting a complex set of stretch surfaces (each building has multiple surfaces and is grouped as a polygon element), these elements are not closed. Each building has an intersection triangle overlapping the source plane and an adjacent overlapping triangle. You can use 3D Union tools to merge all triangles, intersection them, and integrate irrelevant elements within a building to create closed polygon elements.

　　

　　Create a dangerous zone for a steam pipe explosion

Next, you need to generate a dangerous zone that represents the impact area of the steam pipe explosion. Create a vertex element class, add it to arcglobe or arcscene, and use the 3D editor toolbar to add a vertex to the explosion location. Open the Layer Properties dialog box for this layer, and click the symbol system tab to change the symbol system to a simple markup symbol. Use the sphere symbol to indicate an explosion and set the sphere size to the size of the affected area. To Set opacity, click the display tab in the layer properties dialog box, or use the 3D effect toolbar and set the percentage interactively.

　　

To resize, use the symbol property editor dialog box and change the X, Y, and Z values of the symbol respectively. In this example, set the width to 100, the depth to 100, and the size to 300. The final result is a flat-length elliptical body, which represents the volume of space affected by the explosion.

　　

To define a hazardous area, you can use a 3D layer to convert the element type to a polygon. Because the generated polygon is closed, the explosion area can be crossed with the surrounding buildings without additional operations.

　　

　　Intersection polygon Elements

Now, you can use a 3D intersection geographic processing tool to create an intersection between a building and a steam pipe explosion hazard zone. The intersection areas are highlighted in different colors to highlight which parts of the building surface need to be used as contaminated samples.

　　

If you have the corresponding data, you can also use the results of the new intersection to select the internal elements of the Building (such as the room ). In this way, you can quickly obtain a location list to check possible pollution caused by broken windows.

This field guide describes how to use a 3D setup operator geographic processing tool to evaluate which parts of the building surface are used as samples of steam pipe explosion pollution.

ArcGIS Tutorial: Evaluate the steam pipe explosion in the urban environment