Importing Tabular Data

In this activity of ArcGIS importing tabular data was the main objective. Importing data in AcrGIS involves inputting X and Y coordinate data from spreadsheet or access database into ArcGIS. The information provided for this activity were: aparcels shapefile, a claimant_xy.csv table, a sample_location.csv table and a parcel_value.csb table. Using this data we had to make a map on a lawsuit based on contaminants and property values for Bayou Texar. To initiate this activity the shape-files need to be added to ArcGIS but they only show properties and not values. To get the data need we need to merge the tabular data to the shape-files to get the property values. To do this we use the join function and select the Parcel_ID for both shapefiles on the attribute table. Now parcel shapefile need to be added and the claimant needs to be imported. This can be done by going to the File tab, under Add data selecting Add XY and select the claimant_xy.csv table. Thereafter the Coordinate System needs to be changed to WGS1984 in the geographic coordinate systems. This process is repeated for the sample_location_,csv to show the different pointd for each table. Then the parcel_value.csb can be joined with the parcel shapefile and by right clicking on the parcel shapefile and selecting parcel_value. A color ramp was then added by accessing the symbology of the parcel shapefile and selecting market_value and graduated color ramp. The final map should display different colored parcels depending on market value, points that representing Plaintiffs' properties and also the sample location of the contaminants. Basic map elements were then added to finalize the map.

Georeferencing

GIS datasets are usually created specifically for a GIS system complete with geographically referenced coordinate data built in to the file. This is important because these kind of data sets are lined up properly automatically. However there will be times when the data sets do not have coordinate information readily usable by the GIS program. These kinds of datasets usually include digital scanned copies of paper maps and aerial photographs before GIS was used. In this session we will cover the different methods used to input the geographic referencing to an unreferenced dataset and to create geographic data from non GIS ready maps and photos. Georeferencing is the process of making a raster dataset of an aerial photography or digital scan of a paper map to be lined up with a referenced area. To initiate this process we firstly start by adding the unreferenced raster and the referenced raster to the data frame. Then use the fit to display option on the same georeferencing tool to bring the layer you want to reference into the current area that you are viewing and manipulate your display so you can clearly see features on both the known and unknown layers. Secondly you must identify common points from both the referenced and unreferenced rasters and add points to line up both datasets; this is done with the add control points function. First click on the feature on the known area and then click on the same feature on the unknown area. This is process is made easy by adjusting the transparency of a layer; this option is accessed in the layer’s properties. The map is lined up better when the points are evenly scattered. The residual option allows you to view each point added and the total RMS errors. After sufficient points are added the georeferncing needs to be updated so that the data is saved. Secondly the same steps are followed to align the second part of the unreferenced dataset to the referenced dataset and the georeferencing is updated. Both unreferenced datasets must be properly aligned and must be in the 1^st order transformation. The third step is to update the referenced datasets with new feature that were not displayed; these features are a road, a new building and athletic fields. To display these features we used knowledge learnt from the previous sessions to start an editing session to add the new road and the new building with the use of a circle in the middle of the building. For the athletic fields a new shapefile was created to display the four athletic buildings. To finalize the map basic map elements need to be added which are title, scale, legend, north arrow, for this map we also displayed our RMS errors. 

Projections

 In our previous class we used ArcGIS to manipulate how data is displayed and presented in ArcMap. Now we will start making actual changes to datasets in ArcMap. It’s very important to know that although data sets are in different coordinate systems they can still be displayed together. To re-project a dataset you must first access the data management toolbox and go to projections and transformations toolsets and click on the project subset tool since you are using a vector shapefile. The input and output information is then filled and saved in the specific activity folder. The coordinate system is then renamed UTM and added in a separate data frame. Both data frames needs to be activated before they are displayed, slight difference in size are noted from both projections. The second step that needs to be done is to add another field to the attribute table to add area in each specific state. To get the specific area of selected states (Alachua, Escambia, Polk and Miamia-Dade) use the calculate geometry function. A color ramp was also used to identify and label both projections, this was done with an SQL query. To finalize this map both projections needs to be displayed; the major difference will be the size of the states. The maps also need labeling for Alachua, Escambia, Polk and Miamia-Dade as well as labeling for the separate maps which are UTM and Albers. Basic map elements are then added (title, scale, legend and north arrow).