lab_point_to_polygon_and_point_to_raster
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- | ====== KG2204 Exercise 2: Point to Polygon (and more) ====== | ||
- | {{tag> | ||
- | ==Point to Polygon== | ||
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- | Copy the folder '' | ||
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- | Open ArcMap and add the following files: | ||
- | * Point data with ancient monuments (fastighetskartanVektor_FS_1302_epsg3006_point.shp) | ||
- | * Election districts in Sweden (alla_valdistrikt.shp) | ||
- | * Excel file with the population 18 years old or older for each election district (population.xls) | ||
- | * Water (fastighetskartanVektor_MV_1302_epsg3006_polygon.shp) | ||
- | * Rectangle marking the study area (Study_Area.shp) | ||
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- | {{*: | ||
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- | ==1. The intensity of monuments and spatial autocorrelation== | ||
- | Create (20 rows x 20 columns) rectangular polygons covering the study area with the tool: | ||
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- | ArcToolbox » Data Management Tools » Feature Class » Create Fishnet | ||
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- | If not open; click '' | ||
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- | Give the rectangular polygons values for the number of ancient monuments inside them by right clicking on the layer name of the rectangular polygons in the '' | ||
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- | Joins and Relates » Join… | ||
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- | Do: Join data from another layer based on spatial location | ||
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- | Join your rectangular polygons with the ancient monuments. | ||
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- | All the rectangles have the same area and therefore you don’t need to normalize the number of monuments with the area to get the intensity of monuments. | ||
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- | Visualize the intensity of ancient monuments: Right click on the name of the joined layer and choose '' | ||
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- | Go to the tab '' | ||
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- | Quantities » Graduated colors | ||
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- | The value we want to visualize is '' | ||
- | Are there any patterns? Do neighboring polygons tend to be more similar than a random polygon? Check if that is the case by calculating the Moran’s I. | ||
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- | ArcToolbox » Spatial Statistics Tools » Analyzing Patterns » Spatial Autocorrelation (Morans I) | ||
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- | You could use '' | ||
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- | : | ||
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- | Index is the value of Moran’s I (positive if there is spatial autocorrelation and not more than 1). The p value indicate if the result is significant. | ||
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- | ==2. Test the stability of where people live== | ||
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- | Now we ask the data if people tend to live in the same areas today as they did during ancient times. | ||
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- | For that we use the election districts. Some of the election districts include a lot of water. Erase those parts from the election districts using the tool: | ||
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- | ArcToolbox » Analysis Tools » Overlay » Erase | ||
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- | Give the election districts values for the population by joining them with the Excel file. Right click on the layer name of the election district polygons with lakes erased. Choose: | ||
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- | Joins and Relates » Join… | ||
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- | Do: Join attributes from a table using the fields: '' | ||
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- | Now we have the population for each district. We want to calculate the density and therefore also need the area. | ||
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- | Open the attribute table for the election districts layer you have joined with the population. Add a new field for area of the type Float in Table Options (the icon in the upper left corner at the attribute tables). | ||
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- | Right click on the name of the area column and click on '' | ||
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- | Add a new column for the population density (type: Float). Right click on the name of this new column and open the '' | ||
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- | Count the number of points inside of each polygon in the same way as previous with the rectangular polygons (This can take a while). | ||
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- | Create a new column and calculate the density of the monuments. | ||
- | Export the table as a .dbf file using '' | ||
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- | Open Microsoft Excel and open the dbf file (instead of '' | ||
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- | Insert » (Charts) » Scatter » Scatter with only Markers | ||
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- | ==3. Test of monuments are close to water== | ||
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- | If we instead ask the data if ancient monuments tend to be close to water or not, we can start with reusing the previous rectangular polygons with the count of monuments. | ||
- | We also want to create a raster file with the distance to water using the tool '' | ||
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- | ArcToolbox » Spatial Analyst Tools » Distance » Euclidean Distance | ||
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- | Calculate the mean distance to water for each rectangular area using the tool: | ||
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- | ArcToolbox » Spatial Analyst Tools » Zonal » Zonal Statistics as Table | ||
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- | Join this new table to the rectangular polygons and export the joined attribute table and open it in Microsoft Excel. Make a scatter plot for how the count of monuments relates to the mean distance for each rectangle. | ||
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- | Observe that we this time ignored the proportion of the rectangle that consist of water. | ||
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- | ==The End== | ||
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- | Put your intensity map and the two scatter plots in a Microsoft Word document and export the document as a PDF. Send in the PDF file on Mondo. | ||
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- | If you have time you can also practice map design using [[http:// |
lab_point_to_polygon_and_point_to_raster.txt · Last modified: 2020/03/29 14:23 by Stefan Ene