Lab 4

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Feb 20, 2024

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Rachel Schreiber Wednesday 10:00 am – 11:50 am Lab 4 1. (0.75 point) You have used the Los Angeles GeoHub to access data on building outlines in Los Angeles. In your own words, explain what the Los Angeles GeoHub is. Describe at least two examples of water-related data you can find on it. (1 paragraph in total) a. The Los Angeles GeoHub is a public-access software that uses Open Data on a range of topics, such as healthcare facilities and zoning (as well as much more), to allow users to visualize and explore information about Los Angeles using maps and datasets. Two examples of water-related datasets are ‘Ground Water Basins Feature Layer’ and ‘Water Areas’. The ‘Ground Water Basins Feature Layer’ provides information about groundwater basins for public use, such as where they are, their area, and their basin name. The ‘Water Areas’ dataset is also known as the National Hydrography Dataset, which is feature based and dataset that connects and identifies stream segments or reaches that compose the nation’s surface water drainage network. The features in this dataset are organized into polygons, lines, and points 2. (1.25 point) Define VGI and PGI. Compare and contrast VGI and PGI by describing at least two similarities and at least two differences between the two. Using your exploration of building footprint data as a case study, discuss the benefits and drawbacks of VGI and PGI. Provide your screenshot of the discrepancies you noticed between the city’s building footprints dataset and OSM. Refer to the screenshot in your response and discuss the differences. (1-2 paragraph in total) a. VGI, or volunteered geographic information, uses geographic data provided voluntarily by collaborating individuals to create and distribute geographical information for public use. PGI, or professional geographic information, uses geographic information collected and put together by professional or institutional sources. In the example shown below, ArcGIS is PGI and OpenStreetMap is VGI, and from the images it is clear that, in this case, OpenStreetMap (VGI) is far more precise than ArcGIS (PGI). VGI allows for users with personal experience with certain locations to apply their knowledge in a collaborative context. However, relying on individuals to contribute geographic data does leave room for individual error. Yet, as is evident in the less precise ArcGIS map shown below, PGI also can lack specificity and detail because professional/institutional sources do not have personal interactions with the things they’re mapping.

b. ArcGIS OpenStreetMap 3. (2 point) Describe the goal of the HOTOSM platform and the mapping workflow you used to add new features. Briefly describe the project you chose and the project’s relationship with water. Why do you think the project you selected is a good use of VGI? Do you consider the data you created to be accurate? Why or why not? (1-2 paragraphs in total) Provide the screenshots of your additions to OSM. NOTE: I mapped over 20 buildings, but for some reason it’s not showing up on my ‘contributions’ dashboard. As you can see in the screenshot I mapped multiple buildings here but my dashboard still says 0 buildings mapped. a. HOTOSM aims to separate a large-scale mapping initiative into smaller tasks that can be completed by a decentralized network of contributors, all working towards a collective goal. I used the ‘area’ feature to identify and map buildings that were visible on the satellite image map. Once a building area is selected, I selected that it was a building and moved on to any other buildings I could find in the specified area. If I couldn’t find any buildings or roads in an area that needed to be mapped, I selected that the task was completely managed and moved onto another area. Usually areas near roads had more buildings to map. I chose 15097 HONDURAS-OLANCHO 21 , which helps map the lowlands of Central America so that HOT can provide geographical data to humanitarian organizations who are providing aid in the wake of hurricanes in the past few years that have caused flooding and destruction. This project is directly related to changing weather systems and the flooding they cause in an area that may not be equipped to handle such large volumes of water. This project is a good use of VGI because there are no institutions that would have the exact data of where all these tiny buildings are. Thus, it makes sense to rely on the capabilities and integrity of HOT users to identify these buildings to at least lay the foundations for mapping. Even though most mappers will not know the details of what purposes these buildings may serve, it’s important to have at least a base-level amount of information on where people are located in more rural areas, such as the one in this project, for aid purposes and for understanding how future flooding may affect people. I think the data I collected was geographically accurate in that I correctly outlined buildings (see screenshot below). Because I have no personal knowledge of the area, I obviously wasn’t able to provide more detailed information, but that’s okay and it doesn’t

diminish the importance of starting to lay the foundations for more thoroughly mapping the area. 4. (1 point) Today, you created VGI to aid a water-related project. Now, propose a project on a different water-related issue which would be a good use of VGI and the HOTOSM platform. What is the purpose of your project? What features of VGI (e.g., buildings, water, road) will you collect? Who are your intended volunteers? How will you ensure that the data your volunteers create is trustworthy? (1-2 paragraphs in total) (Hint: Search for and browse some water related projects in the HOTOSM). I think a good project for VGI would be mapping vegetation loss due to wildfires in southern California. This issue is related to water because, as we’ve discussed in class, vegetation is a key factor in how water moves over/on land. Without enough vegetation, there will be more mudslides and erosion in cases of heavy rain, weather patterns will change due to shifting rates of evaporation and evapotranspiration, and the ground’s ability to absorb water will change. To properly assess how changes in vegetation would affect the movement of water, this project would need to collect data on roadways, rivers and streams, buildings, and, of course, vegetation. Volunteers from anywhere could map the foundational data, but southern California residents and people with expert knowledge on local river/stream flows and vegetation would need to contribute the more specific details on road names, building functions, and natural features. I would trust any level of volunteer to map the basic building and road features, but only intermediate and expert volunteers could map more complex roadways, building complexes, and vegetation areas.

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Lab 4

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