Arc GIS Pro
Remote Sensing Lab 4 – Introduction to Landsat MSS Imagery 1 Raster Analysis (40 marks) GGR278 Assignment 3 DUE: Mar 24, 2022 by 5:00 PM This assignment is worth 20% of the course grade. The late penalty is 10% per day, including weekends. Assignments will not be accepted more than 5 days late, resulting in a mark of zero. Assignments will be submitted to Quercus on a per question basis. Do not quote from the literature, rephrase in your own words. Objectives: In this assignment you will be introduced to the manipulation and analysis of raster data. Expectations: You can discuss the assignment with your colleagues, but final answers should be in your own words. Data for this lab: The image files for this lab are available from the Quercus Course page. Students should download the data to your local folder or your Medusa StudentWork folder: \\medusa\StudentWork\[your UTORID]\ggr278\Assignment1. See instructions on this page to access the data used in this lab. Software for this lab: ArcGIS Pro will be used to view the data for this exercise. You can use the lab computers or utilize the remote access on Web-based Learning Platform to access the software on the lab computers. Once you login the utmcitrix, click on Desktops on the left panel, and select CCT2130 Desktop during your scheduled practical session. Please note, you can only access the CCT2130 Desktop during your scheduled practical session or any desktop outside of the business hours (i.e. 6pm – 8am ET). https://www.utm.utoronto.ca/geography/copy-data-your-computer-your-working-folder-gge-data-server https://utmcitrix.cloud.com/ 2 Introduction As a GIS specialist and data curator for a large geospatial data asset owner, part of your job is to provide clients with raster data that has sufficient resolution to suit their analysis needs, but minimizes the file storage size to enable faster viewing and analysis. Hence, you offer clients elevation and land cover data at various resolutions. You have a new client who is working near San Cristobal, Venezuela. In support of their work in the region, you have acquired a 90m Shuttle Radar Topography Mission (srtm) elevation raster, and a 90m Global Land Cover Characterization (GLCC) land cover raster. To investigate the influence of cell size on the level of detail, you will explore different techniques to rescale the data and examine the influence of scale. Instructions A) Load the srtm.tif, srtm_9.shp, srtm_81.shp, and srtm_729.shp into ArcGIS Pro. These point files were derived from the original elevation raster srtm.tif. To examine the influence of resolution on the final imagery, convert the point shapefiles back into raster. Open the Point to Raster tool. Set the srtm_9.shp as the input features and set the value field to GRID_CODE (this value represents elevation). To ensure all derived rasters are aligned, go to Environments and set the processing extent AND the snap raster to the same as srtm.tif. Use the measure tool to find the distance between adjacent points and set the cell size to this value! (Make sure the snapping function is enable for accurate measures.) Perform the same action for all three of the srtm point shapefiles (srtm_9.shp, srtm_81.shp, and srtm_729.shp) to generate corresponding rasters (srtm_9rst, srtm_81rst, and srtm_729rst) with correct cell size value. Please note the cell size values for these three rasters are different. 3 Question 1 (1 mark): Explain the differences in the level of detail between the three images, specifically referencing topographical features (1 mark) Question 2 (3 mark): How does the raster resolution affect the shape of the coastline (the white no data region in the North) (1 mark). Describe the mixed pixel problem (1 mark) and explain how it applies to the coastline (1 mark). B) Comparing the three elevation rasters, it is apparent that a larger grid spacing (i.e. larger cell size) results in a loss of detail. However, the loss might be inconsequential. A hydrologist studying water flows from the mountain region would need high detail in order to predict the flow of water, whereas a farmer in a relatively flat region may not need to know about the subtle changes in elevation. Hence, you should compare the profile of elevation between a flat and a mountainous region. C) To create an elevation profile, use the Stack Profile tool which creates a line that extracts the raster value (in this case elevation) along a user drawn line. To create a Stack Profile, navigate to the tool by searching in Geoprocessing Tools. Click the pencil icon and draw a line that fits within the raster extents. Select srtm.tif as your Profile Targets and name your Output Table. Run the tool to create your Stack Profile. Right click on your newly created table (Stack Profile) and navigate to Create Chart > Line Chart. In the Chart Properties (right pane), select FIRST_DIST as your Date or Number value, and select FIRST_Z (elevation) as your Numeric field(s). 4 D) To compare multiple layers, we will use the Stack Profile tool with multiple Profile Targets. First, select any stream segment from the stream.shp file using the Select tool (Map tab > Selection > Select tool). Make sure the stream you choose passes through an area of elevation change. With the stream segment selected, open the Stack Profile tool and input the streams shapefile as the Input Line Features value, add the three stream elevation rasters at each resolution (strm, strm_9, strm_81) as the Profile Targets and rename the output table. Once you’ve created your Stack Profile with the three resolutions, create a Line Chart using the table. Set the Slip by (optional) value to SRC_NAME to separate each elevation profile by raster input. Question 3 (4 marks): Include a copy of the stacked profile showing the three DEMs with the strm in red, the strm_9 in green, and the strm_81 in blue (1 mark). Describe one difference between the data that comprises the three profiles (1 mark). Discuss how the three profiles depict the overall trend (1 mark) and any small scale elevation changes (1 mark). E) To identify flat terrain and the area of sharpest elevation change, we can use the Slope tool. Calculate slope for the srtm, srtm_9, and srtm_81 rasters. Question 4 (3 marks): Attach a screenshot of the profile, and explain why the maximum slope varies between the slope derived from the srtm, srtm_9, srtm_81 rasters (2 marks) and provide an example of the differences in slope (1 mark). F) Since the slope layer is quite complex with sharp variation of elevation, generalize the slope raster could help to clarify the image. Using the slope raster created from srtm.tif, generalize the layer with Focal Statistics tool by properly set the neighborhood and the statistics type parameters. [Hint: you may experiment the different settings of the neighborhood and the statistics type, and then select reasonable settings] Question 5 (6 marks): Please explain how the Focal Statistics tool works (2 mark) and state the proper parameters (the neighborhood and the statistics type) you finally choose to generalize the slope raster (2 mark) and justify your choices with explanation (2 mark). 5 G) Reclassify (with the “Reclassify (Spatial Analyst)” tool) the generalized raster (output of step F) into three classes: flat terrain regions (slope less than or equal to 2 degrees) indicated by the value 1, the medium sloped regions (slopes greater than 2 degrees and less than 50 degrees) indicated by a value of 2, and the steepest sloped areas (slopes greater than or equal to 50 degrees) indicated by a value of 3. Question 6 (2 marks): Based on the reclassified layer in step G), explain in detail how you would find the group of pixels belonging to the steepest slope class (value of 3) with the largest area with the help of spatial analyst tool. H) Use the Resample tool (with Nearest resampling techniques) to change the cell size of Landcover.tif image to the same as srtm_9rst. [Hint: To ensure all derived rasters are aligned, don’t forget go to Environment setting and set the processing extent AND the snap raster to the same as srtm_9rst.] Question 7 (5 marks): Please include a screenshot of the “Resample” tool window and Environments setting window with all parameters properly set (1 mark) and a screenshot of the Landcover image aggregated to the same cell size as srtm_9rst (1 mark). With a study on the 4