Tutorial Competency Review 1

Basic GIS & Remote Sensing Terms Referenced in this Tutorial

• Spatial Analysis:

  • Definition: The process of analyzing spatial data to identify patterns, trends, relationships, and anomalies, often involving operations such as buffering, overlay, and proximity analysis.

• Geoprocessing:

  • Definition: The set of operations and tools used to manipulate and analyze spatial data in a GIS environment, including tasks such as buffering, clipping, and spatial joins.

• Raster Data:

  • Definition: Data that is represented as a grid of cells or pixels, with each cell containing a single value representing a specific attribute or phenomenon, commonly used for continuous spatial data such as elevation or satellite imagery.

• Vector Data:

  • Definition: Data that is represented by discrete geometric objects such as points, lines, and polygons, used to represent features with precise locations and shapes, commonly used for representing geographic features such as roads, rivers, and boundaries.

• Attribute Table:

  • Definition: A tabular data structure associated with a spatial dataset, containing descriptive information or attributes about the features represented in the dataset, often used for storing and analyzing non-spatial data.

• Spatial Join:

  • Definition: A GIS operation that combines attribute data from two or more spatial datasets based on their spatial relationships, such as containment or proximity, resulting in a new dataset that merges the attribute information from the input datasets.

• Buffer Analysis:

  • Definition: A spatial analysis technique used to create a zone or buffer around spatial features based on a specified distance or criteria, commonly used for analyzing proximity and spatial relationships.

• Overlay Analysis:

  • Definition: A spatial analysis technique used to combine or overlay multiple spatial datasets to identify spatial relationships, intersections, or overlaps between features, often resulting in a new dataset that combines the attributes of the input datasets.

• Spatial Join:

  • Definition: A GIS operation that combines attribute data from two or more spatial datasets based on their spatial relationships, such as containment or proximity, resulting in a new dataset that merges the attribute information from the input datasets.

• Zonal Statistics:

  • Definition: A spatial analysis technique used to calculate summary statistics (e.g., mean, median, sum) for raster data within predefined zones or regions defined by vector polygons, commonly used for analyzing spatial patterns and trends.

• Georeferencing:

  • Definition: The process of aligning spatial data to a known coordinate system or reference system to enable accurate spatial analysis and visualization, commonly used for integrating data from different sources or formats.

• Data Visualization:

  • Definition: The graphical representation of spatial data using maps, charts, graphs, or other visual aids to communicate information, patterns, and insights, commonly used for data exploration, analysis, and presentation.

• Geospatial Data:

  • Definition: Data that represents geographic features, phenomena, or attributes associated with specific locations on the Earth's surface, commonly used for mapping, analysis, and decision-making in GIS and remote sensing applications.

• Remote Sensing:

  • Definition: The science and technology of acquiring information about objects or areas on the Earth's surface from a distance, typically using sensors mounted on satellites, aircraft, or drones, commonly used for monitoring and mapping land cover, land use, and environmental changes.

• Data Interpolation:

  • Definition: A spatial analysis technique used to estimate values for locations where data is not available or sparse, based on known values from nearby locations, commonly used for creating continuous surfaces from point data such as elevation or temperature measurements.

• Classification:

  • Definition: The process of categorizing pixels or features within remote sensing imagery into discrete classes or categories based on their spectral characteristics, spatial patterns, or attributes, commonly used for land cover mapping and change detection.

• Normalization:

  • Definition: A data preprocessing technique used to standardize or scale attribute values within a dataset to a common range or distribution, often used to remove biases or variations in data and facilitate comparison and analysis.

• Geospatial Analysis:

  • Definition: The process of analyzing and interpreting geographic data to derive insights, patterns, and relationships, commonly used for solving spatial problems, making decisions, and supporting planning and management activities.

At this point in the semester you have completed your first lab practical and are looking forward to your first exam.  You have completed a number of exercises that have brought you into contact with many many terms & concepts in geospatial analyses.  Here I will walk through these terms and put them within the context of the tutorials you have already completed.

Note that all info about the analyses is take from either the Vector Analyses page (map viewer classic) or the Analyze Tools page (map viewer)

NOTE - clarity on difference between queries and filters: 

In ArcGIS, a query and a filter are both used to narrow down the data you are working with, but they serve slightly different purposes:

• Query:

  • A query is a way to retrieve specific features or records from a dataset based on certain criteria or conditions.

  • It involves specifying parameters such as attribute values, spatial relationships, or both.

  • Queries are often used to extract a subset of data that meets certain criteria for analysis or visualization.

  • They can be performed using SQL (Structured Query Language) expressions or through the graphical user interface in ArcGIS software.

• Filter:

  • A filter, on the other hand, is used to temporarily hide features or records from view within a layer or dataset.

  • Filters do not change the underlying data; they simply control what is displayed on the map or in a table.

  • Filters can be based on attribute values, spatial relationships, or both, similar to queries.

  • Filters are commonly used to focus on specific subsets of data for visualization purposes without permanently altering the dataset.

In summary, while both queries and filters are used to narrow down data in ArcGIS, queries are used to retrieve specific subsets of data based on conditions, while filters control what is displayed without affecting the underlying dataset.

Definitions:

• Spatial Filter:

  • A spatial filter is a tool used in Geographic Information Systems (GIS) to display features based on their spatial relationship with other features or a defined area of interest.

  • Example: In ArcGIS, you can create a spatial filter to display all the buildings within a specific distance of a river. This filter will identify and display only those buildings that fall within the defined distance from the river.

• Spatial Query:

  • A spatial query is a method used in GIS to retrieve features from a dataset based on their spatial relationships with other features or a specified geographic area.

  • Example: You might perform a spatial query to find all the parks within a certain city district. The query will identify and retrieve all the park features that intersect or are contained within the boundaries of the city district.

• Attribute Filter:

  • An attribute filter is used to display features from a dataset based on their attribute values.

  • Example: In a GIS database containing information about land parcels, you could apply an attribute filter to display all parcels with an area greater than 1000 square meters. The filter will display only those parcels that meet the specified attribute criteria.

• Attribute Query:

  • An attribute query is a method used in GIS to retrieve features from a dataset based on specific attribute values or conditions.

  • Example: Suppose you have a GIS dataset containing information about trees, including attributes such as species, height, and diameter. You might perform an attribute query to find all oak trees taller than 10 meters. The query will retrieve and display only those tree features that match the specified attribute criteria.

Perform Analysis in Map Viewer (ArcGIS Online)

Here you use a number of foundational geospatial tools to achieve a series of tasks.  Remember that we cannot possibly cover all the analysis tools available but they are listed here for your reference.

Identify campgrounds near an invasive weed to prevent its spread:  the point of this tutorial is to identify which campgrounds are located near an invasive weed.  This is good to know because a campground being near the invasive weed increases the chances that a camper might unintentionally spread it.  

1. 1. • Dataset(s):  

        1. 1. • These data are already found in the ArcGIS Online catalogue

      • Skill(s) learned:

        1. 1. • Summarize Nearby:  This tool finds features within a specified distance of features in the analysis layer. Distance can be measured as a straight-line distance or a selected travel mode. Statistics are then calculated for the nearby features. In this case you want to calculate the area of Nassella tussock that is within 1.5 km of the campgrounds.   

              • You also Filtered the results to display only those campsite locations that had Nassella tussock within 1.5 km

              • You learned how to make a bar chart (just like GEE!)

Find out how far electric vehicles can travel from a charging station before they need to recharge:  the point of this tutorial is to figure out if EV chargers in Newfoundland are close enough together for residents to use EVs

1. 1. • Dataset(s):  

        1. 1. • These data are already found in the ArcGIS Online catalogue

      • Skill(s) Learned

        1. 1. • You Filtered by multiple attributes (State, Access, DC Fast Count)

              • You conducted a Travel Area Analysis using the charging stations that were left after your filter. The Generate Travel Areas tool uses Esri Service Areas to calculate the area that can be reached within a specified travel time or travel distance along a street network.   You wanted to know which areas where served by these charging station locations.  Areas served was defined as anywhere within 160km driving distance of these stations (EV range).  

Use the Trace Downstream tool to identify flow paths from artisanal mining sites in the Amazon:  the purpose of this tutorial is to take a point where artisanal mining is taking place and trace the downstream flow of pollutants

• Dataset(s):

  • • • These data are already found in the ArcGIS Online catalogue

• Skill(s) Learned

  • • • You used Trace Downstream to follow the watercourse downstream.  The Trace Downstream tool uses a hosted digital elevation model (DEM) to trace downstream flow paths. For analysis purposes, hydrologic information has been precomputed by Esri using standard hydrologic models. 

Find possible locations for a new hospital based on spatial and attribute criteria:  the purpose of this tutorial is to determine the site of a new hospital using a set of criteria

• Dataset(s):

  • • • These data are already found in the ArcGIS Online catalogue

• Skill(s) Learned

  • • • You learned how to create a 2 mile Buffer around a set of roads.  A buffer is an area that covers a given distance from a point, line, or area feature. 

      • You learned to Generate Travel Areas of 20 minutes surrounding the existing hospital

      • You learned to combine both your Buffer layer and your Travel Area layer using the Overlay Layers tool.  Within the tool you chose to do an Intersect and when doing the Intersect you chose to Erase all areas within 2 miles of major roads (buffer) that were also within 20 minutes drive of the original hospital (generate travel areas).  This left you with a layer that includes areas within 2 miles of roads and outside a 20-minute drive to the hospital. 

      • You also learned about Census Tract Data and learned to use both Spatial Queries and Attribute Queries to create an expression.  This expression was used to find Census Tracts that are high growth areas (census data), within 2 miles of a road (buffer) and more than 20 Min from the existing hospital (generate travel areas). 

Improve pedestrian and bicycle safety near schools in your city:  the point of this tutorial is to identify unsafe areas near schools regarding pedestrians and cyclists being struck by vehicles. 

• Dataset(s):

  • • • These data are already found in the ArcGIS Online catalogue

• Skill(s) Learned

  • • • Filter the data so that you are only displaying accidents involving either bicycles or pedestrians (or both)

      • You learned how to simply Aggregate data using the Clustering tool (cluster by radius).  You also learned that you can increase the clustering radius to create fewer (but larger) clusters

      • You learned how to create a Heat Map

      • You learned how to visualize Hot Spots using hexagonal binning

      • You learned how to style symbols using attribute data

      • You again used Generate Travel Areas to calculate a walking distance of 0.5 miles from schools

      • You used the Summarize Within tool to count the number of points (bike or pedestrian accidents) within a 0.5 mile walk of each school

      • You Filtered the school zones so that only the most dangerous (at least 70 accidents) are displayed