GST 101 Introduction to Geospatial Technology��Unit 7 – Introduction to Spatial Analysis�Module 7.2 – Additional Analysis Techniques, including Geospatial Models and Programming����� � �

Ann Johnson

Associate Director

ann@baremt.com

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Based upon work supported by the National Science Foundation under Grants DUE 1304591, DUE 164409, DUE 1700496, DUE 1937177, Due 1938717 DUE 1937237, 2030206 and 2015927. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Common Basic Analysis Techniques

• Query
• Selection
• Classification
• Buffer
• Clip
• Intersect
• Merge
• Union
• Dissolve
• Overlay

Introduction to these techniques and Models and Programming are included in this Module 7.2

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Note: There are 100’s of Techniques and Tools. See GST 102 Spatial Analysis Model Course from the GeoTech Center for additional information

Caution: This Unit described techniques used in Esri’s ArcGIS Pro. Different software packages may use different terms for these analysis techniques

Buffers

Bolstad, Fig. 9-29

Buffer Types

• Dissolved buffers combine overlapping buffer regions
• Compound buffers retain overlapping buffer boundaries
• Nested or multi-ring buffers create buffers at various distances

Bolstad, Fig. 9-30

Buffers Around Museums In Salzburg, Austria

https://learn.arcgis.com/en/projects/build-a-geodatabase-to-support-salzburg-tourism/

Buffer Analysis

• A buffer is a region that is less than or equal to a specified distance from one or more features
• Note difference between vector and raster buffer

Bolstad Fig. 9-27

Raster vs. Vector Buffers

Bolstad Figs. 9-28 and 29

Variable Distance Buffers

• Variable distance buffers use unique buffer distances for different features from the attribute database

Clip, Intersect, and Union

• Clip preserves information from the data layer only for the area of the bounding layer
• Intersect preserves information from the data layer and the bounding layer only for the area of the bounding layer
• Union combines data from both layers over the combined extent of the layers

Geoprocessing

Clip – Using a Feature As a Cookie Cutter

Bolstad, Fig. 9-36 and 38

Clip

Using the Buffer of Mississippi River to Clip out States portions only within Buffer

Merge and Dissolve Functions

• A dissolve operation combines similar features into one feature
• The example to the left shows a dissolve operation to create one polygon region containing the States bordering the Mississippi River

Clip Point Features by a Polygon Feature

Cities with Populations > 30,000 across US in 2007

Cities within Clip Feature of Buffer with Populations > 30,000 in 2007

Hot Spot Analysis

• Sometimes it is hard to visualize significant clusters
• Tools can allow you to find statistically significant clusters – Hot with higher values and cold with lower values
• This could be data based on heath, crime, traffic accidents or other occurrences of data in clusters

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Esri Help - ArcGIS Pro

Spatial Operations or Functions

The set of geographic features used in spatial analysis could pertain to data within only one layer or between 2 or more layers

Bolstad, Fig. 9

Vector Overlay

• Vector overlay involves the merger of both the coordinate and attribute data from two vector layers into a new vector layer

Bolstad 9-34

Overlay Resolution (Dimensionality)

• Overlay output usually uses the resolution of the lowest order input (in this case points)

Bolstad 9-35

Raster Overlay

Raster overlay involves the cell-by-cell combination of two or more data layers

Bolstad 9-41

Problem: Slivers

Slivers can occur when the boundary of a feature on two or more layers is derived from different sources or scales

Bolstad 9-40

Overlay Of Rasters and Vectors – and Analysis

Hillshade

Streams

Faults

Geology

Data Overlay

Roads

DEM

Burn Severity

Landsides

Models

• A Model can be used to “chain” together functions to create an analysis workflow model for analyzing a problem
• This real fire in mountainous area of Southern California uses:
• Degree of burning of vegetation,
• Steepness of slope, and
• Direction the slope faces

to identify locations susceptible to future Landslides (red polygons)

Models can be run, rerun or used in other geographic locations to model possible landslide susceptibility

Blue Ovals – Original Input data and can be a Vector or Raster Dataset

A function – no shadow before model is run and shadowed after run

Green Oval – Output data from function

Functions: Vector to Raster

Reclassify

Weighted overlay combining 3 Rasters

Calculating highest

Final output Raster

Using a Model to find locations where landslides susceptibility is highest using only a digital elevation model and Burn Severity polygons

Arrows show links and direction of analysis

Preliminary outputs

Preliminary output

Programming

• ModelBuilder models can be saved as Python scripts
• Ability to use coding to modifying software programs, to automate or customize analysis tasks are valuable skills
• Different coding options are available for use with geospatial software or to create new software applications
• New apps or extensions to software can also provide coding options
• Python - a high-level, general-purpose programming language using readable code with an object oriented approach
• ArcGIS Pro Notebooks are imbedded Python Within Pro enabling use Jupyter of Notebooks
• Jupyter: open-source web application to create and share live code, equations, visualizations and explanatory text
• R – is an open-source project using extensible packages for statistical computing and graphics
• Json – JavaScript Object Notation is a non-relational database
• GeoJSON is an open standard format that can be used to store

features and attributes and query data

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Artificial Intelligence and Geospatial Technology

• One example from Esri.com
• Use of BIG data to aid in

Deep Learning and analysis

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• View the Concept Module on Artificial Intelligence, Machine Learning, Deep Learning and Internet of Things for an introduction
• https://www.geotechcenter.org/artificial-intelligence-machine-learning-deep-learning-and-internet-of-things8203.html

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While programing and coding are beyond the level of this introductory course on geospatial technology, there is a brief introduction to Python within ArcGIS Pro for beginners from Brian Tomaszewski on YouTube videos at:

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https://www.youtube.com/embed/videoseries?list=PLtrmEEvdG

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For a full course introducing Python see the GeoTech Center Model Course GST 106 – Introduction to Programing at geotechcenter.com

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See GeoTech Center website (https://geotechcenter.org) �for additional Model Courses and other curriculum resources. ���������Note: some content is a derivative of other authors���

Ann Johnson

Associate Director

ann@baremt.com

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2-18-2021 V7