Exercise: Part 1, Mapping for Situation Awareness

Introduction

In this section of the exercise, you will work with two types of UAV-derived geospatial products, orthomosaics, and 3D textured mesh datasets. Your goal is to evaluate ways to use these data to support situational awareness for first responders and urban search and rescue teams. For example, think about suggested plans for an evacuation of the area and providing guidance for where search and rescue teams and damage assessment efforts should focus first. Remember to imagine that this is early data coming in from an emergency situation and that you are tasked with quickly providing spatial products for field operations.

Urban Search and Rescue Team Ready to Enter Area

Credit: By Gabriel - Flickr: 20110224-IMG_9637.jpg, CC BY 2.0, Link

Analysis Steps to Support Field Operations with UAS

Import and process UAV mission data using ArcGIS Pro and Pix4D

1. Install ArcGIS Pro and Pix4D
   You will use ArcGIS Pro and Pix4D to manipulate and interrogate 2D and 3D UAS datasets
   • You probably have ArcGIS Desktop and ArcGIS Pro already installed. If you don’t, this can take some time, so make sure you do it right away. Contact the instructor if you have any questions.
   • You will also need to download and install Pix4D Mapper. Instructions are provided in Canvas. 
2. Access the Data
   I have already processed the raw UAV data with Pix4D for each step in this section because the computing time can be significant. I advise that you do the lesson with the pre-processed data first.  However, feel free to experiment with the data processing steps. There is also an optional exercise that will provide an opportunity for you to process the data on your own using Pix4D.
   1. Begin by accessing the data and associated metadata in the OneDrive folder I shared with you via the the emailed link. Let me know right away if you haven't already downloaded the data. 
   2. The datasets include:
      • A Pix4D Project named Building Scene -- This is also a 3D Textured Mesh, but in this case, it provides a detailed 3D view of a cluster of buildings.
      • A Pix4D Project named Forensic Scene -- This is a 3D Textured Mesh that provides an introduction to what can be done with drone imagery these days. You will contrast this interactive 3D view with the more common 2D view. 
      • An ArcGIS Pro Project named Orthomosaic Industrial Area -- This is a very high-resolution mosaic of many individual photos taken by the UAV. You will start by interpreting and interrogating this dataset before learning more about how these images are created using photogrammetric techniques in Pix4D.
   3. Explore the Data
      As you copy and unzip these datasets, take a moment to review and identify key information from the metadata document (i.e. the mission report). What do you think is most important to understand about the mission and the data? For example, what is the coordinate system and map projection, and do they match the other datasets you might use?

Pix4D Quick Start   

Pix4D is used to develop high-resolution imagery products (2D maps and 3D textured mesh images) based on captured images and their associated location information. So, it is a tool that could be used to develop spatial products in a relatively short period of time. Here, I have provided a quick start tutorial using the buildings dataset.  

1. Double click to open the Pix4D project building_1.p4d. If prompted, navigate to the images folder associated with this project.  

2. Explore the Map View. This shows the general study area and the locations of where the UAV images were taken, denoted by the red circles. Go ahead and click on one of the circles to see the corresponding image and parameters.  

3. Open the Processing Options by selecting the button on the lower left of the display. This is where you set up the parameters for processing the raw imagery. Some of the options for outputs include point cloud, 3D mesh, Digital surface model, or Orthomosaic. There is also a panel that shows Resources and Notifications. You can view the resources available on your computer to do the processing. 

4. Look at Processing panel (also at the lower left of the display). This shows the selected options and allows you to launch the model. NOTE: Because Pix4D can be really resource intensive, I have already generated output for you to consider. However, feel free to have a go at running this yourself – it just might take a while.  

Now have a look at the processed results and explore some of the options for interrogating the data.  

1. Select rayCloud view from the left hand options. Zoom in and note what is being displayed – toggle layers on and off.  
2. Deactivate the Tie Point layer and look at the Cameras layer. This shows you the location and orientation of the camera at the time of acquisition by the UAV. 
3. Activate the Point Clouds (and Point Groups) layers. This shows the point could be generated from the imagery and location information.  
4. Activate Triangle Meshes and deactivate all other layers. This 3D textured mesh combines the 3D geometry with the imagery.  
5. Explore the 3D textured mesh with the available tools in the Navigation and View toolbars.
   • Traditional pan and zoom with the standard navigation
   • 3D trackball navigation
   • Focus on the Selection tool
   • View from Top tool

Interrogate 2D Orthomosaic imagery

1. Open the ArcGIS Pro Project and have a look at what’s there. Examine the flight trajectory map and refer back to the mission report if you need to. Note the area covered and any variation in the quality of the mission. It is worth noting that you may not have complete coverage of the impacted area. That's where some historical imagery can be useful, as it allows you to provide advice about other potential nearby hazards, e.g., what do you do if the SAR teams are moving into places that are downstream from floodwater or hazardous facilities?
2. Note that these high resolution images have already been orthorectified and mosaicked by the drone data processing software (in this case Pix4D Mapper). So, soon after the mission, the data are provided to you in ready-to-use form. There are other courses and training you can do if you are interested in photogrammetry and image processing. There are a lot of services that can do this for you as well, and you have the option to work with Pix4D Mapper below.
3. Familiarize yourself with the content of the scene by panning and zooming around the image. Think about the advantages of having such high-resolution imagery when going into an uncertain environment. Start with some general observations about the industrial park, e.g., entrances and exits and then consider specific types of activities that are evident in the imagery through observing things like forklifts, loading areas, and liquid nitrogen stacks.
4. Create a point feature class in ArcGIS Pro and map five or more locations within the study area that you think are important for first responders and search and rescue teams to know about. These locations could include things like barriers (e.g., narrow access points, obstacles, dead ends), access points for responders and equipment, or potential hazards. There are no wrong answers here. The point is for you to get a sense for just how much information you can quickly gain from UAV data products.

Interrogate 3D Textured Mesh Data

1. In this part of the exercise, you will work with UAV-derived 3D Textured Mesh Data data in Pix4D Mapper.
   • You will be using this program as a way to explore the data rather than processing the raw imagery. Processing large UAV datasets can take considerable time (up to several hours) and the idea here is for you to use these products to think about an emergency management problem. That said, in the next OPTIONAL section, you can take a deeper dive and process some imagery yourself if you like. 
   • You will look at two examples of 3D Textured Mesh models. These are high-resolution 3D models of locations that also have imagery draped over them in an accurate and realistic way. For example, you could move around a building to view a particular exit or even see fine details such as car headlights. Again, consider the implications of having access to this data product for emergency management operations and situation awareness.
2. Open the Pix4D Mapper project Forensic-1.p4d
   • Go to the Map View. Look at the study area and flight path.
   • Go to the Ray View and note the different Layers.
   • Toggle each layer on and off and note what each is representing and how it illustrates how the final products are derived. For example, note the camera locations and how they are linked to one another and the derived point cloud.
   • Turn off all layers except for the Triangle Meshes dataset. Pan and zoom around the image and make some observations about what you think would be useful for emergency teams with access to this level of detail.
3. Repeat these steps with the Pix4D Mapper project Building-1, but consider the greater complexity in this scene from the point of view of supporting emergency response activities. 

Later in the course, you will learn about using geoAI and machine learning for rapid, automated assessment of imagery like this. We will also consider how data like this can be delivered more effectively to first responders and others in the field during emergencies.