Summer sci425_module_three_technical_writing_sample (2)

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Southern New Hampshire University *

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Geography

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Jan 9, 2024

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Summer Brooks SCI 425 Module Three Technical Writing Sample Tutorial: Access Satellite Imagery Through ArcGIS Key terms for this tutorial: Composite image processing : The composite image processing technique allows a GIS user to combine multiple bands into a single raster. Although this is a somewhat complicated process, it allows the raster to be viewed as a multispectral image in ArcGIS. Normalized digital vegetation index image processing : The NDVI is a standardized index that permits a GIS user to generate an image that displays greenness. This band combination capitalizes on the differences between the red band and near-infrared band to detect the presence or absence of green vegetation. Raster data set : A raster data set is any valid format of raster data that uses one or more bands. Mosaic data set : A mosaic data set is a collection of raster data sets displayed dynamically in a GIS. This format allows users to analyze larger swaths of imagery. Image service : An image service provides access to stored imagery through a web service. It allows a GIS user to manipulate and analyze data stored on a remote server dynamically in a GIS. 1. DRA : DRA or dynamic range adjustment allows the GIS user to brighten and contrast the data using only the data present within the data frame extent. Open up a new ArcMap document. 2. Access the ArcMap catalog and open the GIS server. 3. Double-click Add ArcGIS Server and click Next on Use GIS Services.

4. In the server URL, paste: http://imagery.arcgisonline.com/arcgis/services . Next, click Finish . Now the ArcGIS on Imagery service should be available. Once the imagery service has been added, open the Imagery service and expand the LandsatGLS folder. Add the TM_Multispectral_1990 Image data set. The resulting image data set should be similar to the one pictured below. 5. Once the TM_Multispectral_1990 Image data set has been added, zoom to a city of interest. 6. The city you are studying may look dark due to the stretch value of the image is using the entire world to assign values. Go ahead and open the image analysis window (in the window drop- down tab) and left-click the pin button and the TM multispectral 1990 so that it is highlighted.

7. Once you have opened your image analysis window, click on the DRA button. This should brighten your imagery because the values are stretched to use only values within the current extent. Adjust the contrast and brightness filters until the image is enhanced to your preference. (Aerial of Phoenix) 8. Next, create a bookmark and label it ‘yourcityextent’ (e.g., Phoenix extent). 9. Once the bookmark is created go to the processing section of your image tab and left-click the clip function. The clip function will create a new raster data set the size of the current extent. TIP: Export the new raster data and save it to your computer, e.g., Phoenix1990. (This could serve as a 7 band Raster data set to conduct a temporal analysis.) 10. Deactivate the TM_Multispectral_1990 Imagery service so that your clip is the only raster data set that is currently visible. Make sure the clip is highlighted within the image analysis window and then return to the processing area. Left-click the green leaf aka the NDVI function. A new NDVI raster data set will be added to ArcMap for your city.

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