exam2_problems_spring2024_engelmanj

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Mechanical Engineering

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Apr 3, 2024

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docx

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o u t g ri d zon e gri d 4 1 2 5 5 0 1 1 5 1 valu e gri d 1 1 6 4 8 6 0 2 4 2 1 1 4 4 4 0 5 4 1 6 0 8 8 = 3 3 3 0 0 0 0 5 5 4 4 4 4 1 2 3 2 2 1 1 GIST 420 Name Joseph Engelman Exam 2 Spring 2024 Rasters and raster processing Given the zone raster and value raster at right, calculate the zonal variety for the output raster. (6pts) 3 3 3 3 ND 3 3 3 3 3 2 2 4 4 4 2 3 3 3 4 2 ND 2 2 4 outgrid Surfaces 1. The images below are two symbolized slope rasters labelled 1 and 2 with elevation contours overlaying them. The darker colors on the raster indicate higher slope values. Which slope surface was derived from a DEM interpolated using IDW , and which from a DEM interpolated using Topo to Raster? What is it about these interpolation methods that caused the differences in the slope surfaces? (5 points)
Image 1 is a DEM interpolated using IDW and image 2 is a DEM interpolated using Topo to Raster. The IDW tool is a method of interpolation that estimates cell values by averaging the values of sample data points close to each processing cell. The closer a point is to the center of the cell being estimated, the more influence it has in the averaging process. On the other hand, the Topo to Raster tool uses an interpolation technique that is specifically designed to create a surface that closely represents a natural drainage surface. This tool better preserves both ridgelines and stream networks from input contour data. 2. In the image below, the Explore tool has been used to select a facet of a TIN. The popup displays values for three attributes -- elevation, slope, and aspect. When using the Explore tool in ArcGIS Pro to query different locations within the same triangle , which, if any, of these three attributes would return different values at different locations within the triangle and explain why. (5 pts) The Tin_Surface example shows that all three values can change when you click on a different location within a triangle. TINs are made of non-overlapping triangles calculated from irregularly 2 2 1
spaced points that have X, Y, and Z values. Even if you choose a new point within the same triangle, it will alter the horizontal position (X, Y) and the elevation (Z) values. DEM Hydrology 1. Using the flow direction code, calculate flow accumulation from the flow direction grid. (10 pts) 0 0 0 0 0 0 1 2 2 0 0 3 4 3 0 0 0 14 0 1 0 0 2 19 0 2. Briefly describe how an ArcGIS “con” statement is used to differentiate streamflow from surface flow from a flow accumulation raster? (2pts) The "Con" statement in ArcGIS lets you apply conditions to raster datasets to create new ones based on specific criteria. For instance, you can use it to differentiate between streamflow and surface flow in a flow accumulation raster. To do this, you set up a conditional expression by comparing flow accumulation raster values to the threshold value. In the output raster, areas where the flow accumulation exceeds the threshold value, are considered streamflow, whereas areas below the threshold represent surface flow or less significant drainage features. Python and Notebooks 1. Consider the short python code section below. (4 pts) 3
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