Exercise
1.Download data and display files
Download Field_Area.zip from Lab 6.5 on the angel web site and save it in your local computer （e.g. Desktop）or your USB flash media. Then unzip it. This data size is almost 70 MB.
Start ArcMap by clicking your Start menu, then clicking All Programs -> Course Software -> ArcGIS -> ArcMap.If you see a dialog, choose the option to start using ArcMap with an existing map and double-click "Browse for maps."
If you don't see the dialog, click the Open button.
Navigate toField Area folder you have saved.
Double-click Field_Area.mxd to open the map document.You will see the map of the Okemos/Haslet and Williamston.
2. Setting
First of all, click Tools-> Extensions. Extensions dialog opens. Turn on the check box of Spatial Analyst. Click close(you may click About Extensions to see the description of extensions).
Click View -> Toolbars. Check Editor and Spatial Analyst. Make sure Editor toolbar and Spatial Analyst toolbar are displayed.
3.Exploring geographic data sets
ArcMap offers advantages for exploring geographic data: you can view many data layers at once. Turn on the check boxes of some layers in which you are interested and confirm what is displayed. Also you can expand the map by using Zoom In tool in the Tool toolbar.
4.Extractthe site
Right click the Survey Area and choose Zoom To Layer.Turn on the check box of the Survey Area layer. You will make the polygon where the area should be calculated. In the Editor toolbar, click Editor and choose Start Editing. Make sure ‘Create New Feature’ is selected for Task and ‘Survey Area’ is selected for Target. Click Sketch tool.You can make a new polygon by clicking the mouse as instructed below.
In the Editor toolbar, click Editor and choose Stop Editing. Save dialog opens, click Yes. The new polygon is drawn by red line.
From the Selection menu, choose Select By Attributes. The Select By Attributes dialog opens.Next to the Layer field, click the down arrow and choose Survey Area if it is not already selected. In the Method field, the default method, "Create a new selection," is selected. This is what you want. In the Fields list, double-click [FID].
The field is added to the expression box below the Fields list. Click the equals sign button. Click Get Unique Values. In the Unique Values list, double-click '1', which indicate a new polygon.Click Apply and then Close.
The new polygon is selected. Right-click Survey Area in the Table of Contents, choose Data, then click Export Data.
In the Export Data dialog, click the Browse button next to the Output shapefile or feature class field and navigate to yourField Areafolder.
For Name, enter New_Area. Click Save, then OK. Click Yes to add the data as a layer to the map.
5.Area Calculation
Right click New_Area, choose Open Attribute Table. Attributes of New_Areadialog opens. Click Options and choose Add Field. Add Field dialogopens. Enter AREA in the Name field and click the down arrow in the Type field and choose Double. Click OK. AREA field is added.
In the Editor Toolbar, Click Editor and choose Start Editing.
Right click AREA in the Attributes of New_Area, and choose Calculate Values. Field Calculator dialog is launched. In the middle of the dialog, check the box next to‘Advanced’.
Enter the VBA(Visual Basic of Application) script in the Pre-Logic VBAScript Code as follows.
You do not need to understand the VBA because the commonly used VBA scripts are shown on the some web sites. The above is the scripts to calculate the area (acre).
Click OK. In the AREA field, the area of New_Area is calculated.The unit of area is acre. Click Close. Click Editor in the Editor Toolbar, and then choose Stop Editing.
6.Histogram
For the Layer fieldin the Spatial Analyst Toolbar, click the down arrow and choose luse78. Then click the histogram button. Histogram of luse78 dialog opens.
The number of Value field corresponds to the land use type as shown below.Close Histogram of luse78 dialog.
Number / Land use type1 / Agricultural Land
2 / Rangeland
3 / Wetlands
4 / ForestLand
5 / Urban and Built Up
6 / Barren
7 / Water
7. Two-way cross tabulation
In this section, you will produce the cross tabulation of land use and soils. There are some layers of land use and soils in the Table of Contents which may be distinguished by the data type as shown below.
Vector / RasterSoils / soil_grid
landuse1978 / luse78
landuse1992 / luse92
The raster data model is very useful for representing continuous geographic data; that is, phenomena such as land use and soils, which don't have well-defined boundaries and which usually change gradually across a given area. When used to represent continuous data, each raster cell value is a measure of the phenomenon being modeled. For example, in an elevation raster, each cell value represents the elevation of a particular area. The raster data model is commonly used for spatial analysis and modeling.The cross tabulation is one of spatial analysis, so we will deal with raster data sets in this section.
Click the ArcToolbox button. Expand Spatial Analyst Tools, and then expand Zonal. Double-click Tabulate Area.The tabulate area tool dialog displays.On the right, read the description of what the Tabulate area tool does (you may need to click Show Help to see the description).
For Input raster or features zone data field, you need to select the two layers you want to calculate. Next to the Input raster or features field, click the down arrow and choose ‘luse78’. Make sure ‘Value’ is displayed in the Zone field. Next to the Input raster or features field, click the down arrow and choose ‘soil_grid’.Make sure ‘Value’ is also displayed in the Zone field.
For Output table in the Tabulate Area dialog, select the output location (Field_Area folder) and the output table name (Tabulat_luse781.dbf) are fine. Also the default Processing cell size 30, which means 30 meters, is fine. Click OK.
Open Microsoft Excel and then open the file Tabulat_lu781.dbf. You see the cross tabulation.The row number (VALUE_1 to 52) corresponds to the soil typeas shown below and the column number (1 to 7) corresponds to the land use type as shown above
Number / Map Unit Symbol / Map Unit NameVALUE_1 / Co / Colwood-Brookston loams
VALUE_2 / OwB / Owosso-Marlette sandy loams, 2 to 6 percent slopes
VALUE_3 / MaB / Marlette fine sandy loam, 2 to 6 percent slopes
VALUE_4 / Hn / Houghton muck
VALUE_5 / AnA / Aubbeenaubbee-Capac sandy loams, 0 to 3 percent slopes
VALUE_6 / SpB / Spink loamy sand, 0 to 6 percent slopes
VALUE_7 / RdB / Riddles-Hillsdale sandy loams, 2 to 6 percent slopes
VALUE_8 / CaA / Capac loam, 0 to 3 percent slopes
VALUE_9 / Gr / Granby loamy fine sand
VALUE_10 / W / Water
VALUE_11 / ByA / Brandy sandy loam, 0 to 3 percent slopes
VALUE_12 / Pt / Pits
VALUE_13 / Ka / Keowns very fine sandy loam
VALUE_14 / KbA / Kibbie loam, 0 to 3 percent slopes
VALUE_15 / UpA / Urban land-Capac-Colwood complex, 0 to 4 percent slopes
VALUE_16 / Ha / Histosols and Aquents, ponded
VALUE_17 / Ed / Edwards muck
VALUE_18 / OwC / Owosso-Marlette sandy loams, 6 to 12 percent slopes
VALUE_19 / MtB / Metea loamy sand, 2 to 6 percent slopes
VALUE_20 / ThA / Thetford loamy sand, 0 to 3 percent slopes
VALUE_21 / UtB / Urban land-Marlette complex, 2 to 12 percent slopes
VALUE_22 / BrB / Boyer sandy loam, 0 to 6 percent slopes
VALUE_23 / Gf / Gilford sandy loam
VALUE_24 / UeB / Urban land-Boyer-Spinks complex, 0 to 10 percent slopes
VALUE_25 / OtC / Oshtemo-Spinks loamy sands, 6 to 12 percent slopes
VALUE_26 / MaC / Marlette fine sandy loam, 6 to 12 percent slopes
VALUE_27 / MtC / Metea loamy sand, 6 to 12 percent slopes
VALUE_28 / Ud / Udorthents and Udipsamments
VALUE_29 / Ad / Adrian muck
VALUE_30 / Bo / Boots muck
VALUE_31 / RdD / Riddles-Hillsdale sandy loams, 12 to 18 percent slopes
VALUE_32 / SnC / Sisson fine sandy loam, 6 to 12 percent slopes
VALUE_33 / RdC / Riddles-Hillsdale sandy loams, 6 to 12 percent slopes
VALUE_34 / SnB / Sisson fine sandy loam, 2 to 6 percent slopes
VALUE_35 / SpC / Spink loamy sand, 6 to 12 percent slopes
VALUE_36 / MeD2 / Maelette loam, 12 to 18 percent slope, eroded
VALUE_37 / Uu / Urban land-Fluvaquents complex
VALUE_38 / OtB / Oshtemo-Spinks loamy sands, 0 to 6 percent slopes
VALUE_39 / OsC / Oshtemo sandy loam, 6 to 12 percent slopes
VALUE_40 / Pa / Palms muck
VALUE_41 / Sb / Sebewa loam
VALUE_42 / Ce / Ceresco fine sandy loam
VALUE_43 / OsB / Oshtemo sandy loam, 0 to 6 percent slopes
VALUE_44 / BsD / Boyer-Spinks loamy sands, 12 to 18 percent slopes
VALUE_45 / Ch / Cohoctah silt loam
VALUE_46 / MoE / Marlette-Boyer complex, 18 to 25 percent slopes
VALUE_47 / MrA / Matherton sandy loam, 0 to 3 percent slopes
VALUE_48 / Na / Napoleon muck
VALUE_49 / Ln / Lenawee silty clay loam
VALUE_50 / Au / Aurelius muck
VALUE_51 / BsE / Boyer-Spinks loamy sands, 18 to 30 percent slopes
VALUE_52 / EvB / Eleva variant channery sandy loam, 2 to 6 percent slopes
8. Overlay analysis ( weighted or unweighted)
In this section, you will learn overlay method through analyzing the land-use change between 1978 and 1992.
8.1 Reclassify
We will focus on the land-use change of agricultural lands and need to modify the attribute value.In the Spatial Analyst Toolbar, Click Spatial Analyst and choose Reclassify. Reclassify dialog opens. For the Input raster field, click the down arrow and choose luse78. For the Reclass field, click the down arrow and choose Value. Set New values to reclassify as shown below.
Old value / New value1 / 1
2 / 0
3 / 0
4 / 0
5 / 0
6 / 0
7 / 0
No data / No data
For output raster field, click the Open button and navigate to the Field_Area folder. For Name, input the ‘lu78_XXX’(XXX is your favorite nameor number). Click save and OK. The layer of lu78_XXX is added in the table of contents.
8.2 Overlay analysis
In the Spatial Analyst Toolbar, Click Spatial Analyst and choose Raster Calculator.Raster Calculator dialog opens. For Layers, double click lu78_XXX. The field is added to the expression box below the Fields list. Click the * sign button and input 100. Click + sign button and double click luse92in the Layers field. Click Evaluate.
‘Calculation’ layer is added in the Table of Contents.
Right click ‘Calculation’ and choose Properties. Select Symbology tab and select Unique Values for Show field. You can see all unique values. Lu78_XXX is weighted 100 times. So land-use conversion from AgriculturalLand to land use in 1992 is represented as the number between 111 and 192.
You can see the spatial distribution of land-use changes if you modify the Legend.Right click Calculation and choose Properties. Select Symbology Tab and click Import button. Choose Calculation.lyr, which is prepared for the exercise, then click Add. Click OK. Land use change from agricultural land is displayed spatially.Right Click Survey Area layer, choose Zoom To Layer.The result map is shown below.
9. Save as a graphic file and Print out
You can save this graphic as a graphics file. Click the Layout View button. From the File menu, choose Export Map. In the Export Map dialog, navigate to your local folder,such as your local computer or USB flash drive and so on.
Name the file your favorite name. In the Type of file click dropdown list, and choose JPEG (*.jpeg).You can use this graphic file in the Microsoft PowerPoint and other softwares.