Minnesota Department of Natural Resources ArcView Utilities Extension User s Guide

Transcription

1 Introduction This document describes the functionality and use of the ArcView Utilities extension for the ArcView desktop GIS software. These tools were developed out of the need for additional geoprocessing functionality within ArcView by resource managers. The ArcView Utilities extension contains a number of extended GIS functions that are commonly used by resource managers but not available on the standard ArcView interface. The remainder of this document will describe the available tools and will use examples to illustrate what they do and how they work. ArcView Utilities Menu The ArcView Utilities is a form that contains a number of buttons that perform a variety of GIS processing functions. Some of these are directly related to geographic analysis (clip, buffer, intersect etc) and some are general utility commands that have been commonly requested. If you need to install the extension, refer to appendix A, Installation of ArcView Extensions. Last Updated 1/22/98 - Tim Loesch Page 1

2 Accessing Extensions To access the utilities form within ArcView you can use the FILE: Extensions option when the project window is active. Loading the Utilities Extension Once selected you will see the Extensions Dialog window that shows the extensions that are available to ArcView. Scrolldown until you see ArcView Utilities-DD and click on the check box adjacent to it. Then press the OK button. Page 2

3 ArcView Utilities Form The ArcView Utilities form will then appear. The form consists of nine buttons. Each button operates on one or more themes to produce a new output theme (in most cases). This is a modeless form, that is, it can be moved around the screen and used when needed. Other menus, buttons and tools on the interface are fully accessible when this form is open. To use a button on the Utilities form, simply press it with the mouse pointer. That s it. Depending on the function of the button you will be prompted for additional information. What do the Icons Mean? As you move the mouse pointer over the buttons on the form a message will appear in the status bar of the ArcView interface (at the bottom of the ArcView window). If you hold the mouse pointer on a button momentarily, a bubble with text will appear that shows a short description of the buttons functionality. NOTE: The bubble text capability is only available with Windows 95 or Windows NT. For Windows 3.x or UNIX machines refer to the bottom of the ArcView window for help. Page 3

4 ! Closing the Utilities Form Re-Opening the Utilities Form To close the form just press the X button in the upper right hand portion of the form s banner. This does not unload the extension, it simply closes the form and frees up display space on your monitor. Once the form has been closed it can be re-opened, as long as the extension is loaded, using the WINDOW: Show ArcView Tools option. This will re-open the form and make the commands accessible to you. Unloading the Utilities Extension To unload the ArcView Utilities extension you must access the Extensions dialog through the FILE: Extensions option and unchecking the box next to the ArcView Utility Tools extension selection. This will remove the form, and menu options related to it, from the current ArcView session. Page 4

5 TABLE OF CONTENTS CLIP - Page 7 BUFFER Page 13 INTERSECT - Page 19 MERGE - Page 25 ERASE - Page 29 UNION - Page 33 SUBSET LEGEND - Page 39 CALCULATE AREA, PERIMETER LENGTH - Page 43 SHIFT COORDINATES - Page 45 MULTI-POINT TO POINT - Page 51 UNGROUP POLYGONS - Page 55 Appendix A - Installation of ArcView Extensions - Page 59 Page 5

6 This page intentionally left blank. Page 6

7 The CLIP Button Why CLIP? The CLIP Button is used to extract subsets of information from existing geographic data sets. This is equivalent to taking a spatial cookie cutter to some geographic dough. You take the outline of something, a watershed, city or county for example, and press it into the dough. In this case the dough is a geographic data set. Clipping is useful when you want to perform an analysis on a specific area. Think about how people work. A wildlife manager may be developing a management plan for an existing wildlife management area or a planner may be working on a county plan. They don t need data for the remainder of the state to do the task at hand. By clipping geographic databases you can reduce the amount of information your computer has to load into memory when you access the data. The reduction in data volume will speed up your computer by freeing memory resources and will maximize disk space. What do I Need to CLIP? The clipping process requires two or more themes as input. The Clipping Theme is a polygon theme where a polygon, or set of polygons, defines the outline of the area to be Clipped. This theme is the geographic cookie cutter. The Themes to be Clipped are the themes whose data you want to extract. These themes are your geographic dough. The themes to be clipped can be Shapefiles, Coverages or Librarian layers that contains points, lines or polygons. The Clipping Theme must be a polygon theme that has one or more polygons selected. What does CLIP Produce? The CLIP process produces new shapefiles that contains the features of the Themes to be Clipped that fall inside the selected polygons of the Clipping Theme. The theme attribute tables will contain the fields that were in the Theme to be Clipped and the Area/Perimeter/Length and acres fields will be updated based on the new values. Page 7

8 An Example Clip Let s say that you are working in Crow Wing county, MN and want to look at the Pre-Settlement vegetation for the county. You have a file that shows the Pre-Settlement vegetation for the state and another shapefile that shows the counties in Minnesota. What you want is a subset of the Pre-Settlement vegetation for Crow Wing county. This is a perfect time for a CLIP. You see the two maps below, in this case the Pre-Settlement vegetation is the theme to be clipped (dough) and the county theme is the clipping theme (cookie-cutter). Pre-Settlement Vegetation Theme to be Clipped Counties in Minnesota The Clipping Theme Step 1 - Select the Clipping Polygons The first step in the clipping process is to select the polygon that represents Crow Wing county in the county theme. If you wanted to you could select more than one county and their combined outline would be used as the clipping polygon. You must also make sure that you have the theme to be clipped on the View document. Page 8

9 An Example Clip CLIP Button Step 2- Press the CLIP Button Once you have the two themes on the View and the clipping polygons selected you are ready to proceed. If the ArcView Utilities form is open press the CLIP Button. If the form is not open, use the WINDOW: Show ArcView Utility Tools option to open it. Step 3- Select the Theme(s) to be Clipped Once the CLIP command is selected the CLIP Themes form will appear. This form is made up of a list of themes to clip to the left and a dropdown box that shows the polygon themes in the View that are available for use as clipping themes. While you could select several themes in this list, in this case we are only interested in clipping the Pre-Settlement Vegetation theme. Page 9

10 An Example Clip Step 4- Select the Clipping Theme Then specify the clipping theme by selecting the appropriate theme from the drop-down list of polygon themes in the right hand side of the form. Remember that one or more polygons in this theme must be selected. If not, you will get the following error message. Step 5- Retain or Change Filenames AT this point the program is ready to go out and clip the theme or themes that you specified. At this time the program needs to know where you want to store the new files and how you want the filenames to be handled. There are two options, retain the current filename or change the filenames to something else. This is indicated bye the Change Filenames checkbox on the CLIP Themes form. By default, this check-box is not selected so the original name of the file will be retained. If you change the filenames you will be required to enter a new filename for the output shapefile. If not, you will simply need to specify an output location. In most cases it is desirable to retain the original filename. When you are finished entering the paramters on the Form press the OK button to proceed. Page 10

11 An Example Clip If the program finds any files in the output location that are in danger of being overwritten you will be prompted to see if that s what you really want to do. If so, press OK and the process will proceed. CLIP Results What you see above is the resulting shapefile that was produced from the CLIP procedure. As you can see, just the part of the Pre- Settlement Vegetation coverage that occupied the outline of Crow Wing county was copied into the output shapefile. Page 11

12 This page intentionally left blank. Page 12

13 The BUFFER Button Why Buffer? What do I Need to Buffer? How are Buffer Distances Entered? What Does Buffer Produce? The Buffer Button is used to create a buffer around the selected objects within a geographic data set. The distance of the buffer is defined by the user. Buffering is useful when you want to identify features that exist within a certain distance of features of interest. You can then use the output buffered shapefile as a Clip Theme in the CLIP command. This would leave you with a file that contained only those features within the buffer zone. The buffer process requires one theme as input. The theme to be buffered can be a Shapefile, Coverage or Librarian layer that contains points, lines or polygons and one or more of these features must be selected. Buffer distances are entered based on the Map or Distance units specified in the View Property Sheet. Distance units are used first. If they are not specified then the Map units property is used as an input measure. Negative values for buffers are allowed on polygon features only. In this case, a buffer on the inside of the polygon will be created rather than a buffer outside of the polygon. The Buffer process generates a new shapefile that contains polygons that represent the boundaries of the buffered area. The output theme attribute table will contain two fields, SHAPE and INSIDE. The Shape field is defined by ArcView and the INSIDE field value of 1 represents a polygon that is inside the buffer area while a value of 100 represents polygons formed that are outside the buffer area. All polygons generated are considered a single entity. If you wish to separate these polygons use the UNGROUP Button. If you wish to add the AREA, PERIMETER and ACREs fields, use the UPDATE AREA/PERIMETER/LENGTH button. Page 13

14 An Example Buffer Let s say that you have a number of Eagle s nests inventoried and stored as point locations in an ArcView shapefile. What you want to do is create a new file that shows a buffer zone around the eagle s nests of 1/4 mile or This data set has been added to a View and is named Eagle s Nests. Below is a picture of the Eagle s Nests with a river feature added to the display for visual context. Step 1 - Select the Features to be Buffered The first step in the buffering process is to select the features that you want to buffer. Using the Selection tool, select the features of interest. In this case we ll select all of the eagle s nests in the file. Remember to have the theme of interest active and then use the feature selection tool to select the features. Once you have selected features they will be highlighted in the current selection color (usually yellow). Page 14

15 An Example Buffer BUFFER Button Step 2 - Press the BUFFER Button Once you have the feature of interest selected you are ready to buffer. If the ArcView Utilities form is open, press the BUFFER Button. If the form is not open, use the WINDOW: Show ArcView Utility Tools option to open it. Remember that the buffer option relies on the value of the Map Units in the View s Property sheet. If the Map Units have not been set, you will see the following message: You will need to edit the property sheet of the View before you can continue. Use the VIEW: Properties option to define the Map units property. If you do not have any features selected you will get the following message: Page 15

16 An Example Buffer Step 3 - Enter the Buffer Distance Step 4 - Enter a New Filename Now you are ready to define the Buffer size. Enter the size of the buffer in the units that are defined in the dialog. In the above example, the Distance units of the View is Miles, therefore the dialog requests the buffer distance in miles. We want a 1/4 mile buffer so the appropriate entry is You will then be asked to enter a new filename and location. The default shapefile name is BUFFER.SHP. You can change this as you like. Once entered the Buffer command will commence and a buffered theme added to the View. The picture below shows the results of this operation. The green polygons represent the buffer polygons. Page 16

17 An Example Buffer Buffer Notes Ungroup Button If you look at the above graphic of the theme attribute table for the buffered Eagle s nests you will see that there is only one record. This record represents all of the polygons that were created. If you select one, all are selected. If you want to split these into individual polygons that each have a record in the theme attribute table use the Ungroup Polygons button on the ArcView Utilities form. The result will be the table below Page 17

18 This page intentionally left blank. Page 18

19 The INTERSECT Button Why INTERSECT? What do I Need to INTERSECT? What does INTERSECT Produce? The INTERSECT Button is used to perform a spatial overlay of two themes to determine the spatial coincidence of the features in the themes. Intersection is useful when you want to look at one mapped variable in relation to another mapped variable. A fisheries manager may want to know what the land cover is in each watershed in their management area to determine if there is any relationship between the land cover types and the water quality of the lakes in a watershed. The intersect command is the way to get the job done. The Intersection process requires two themes as input. An Intersect Theme which can be a line or polygon theme, and an Overlay Theme which must be a polygon theme. In the previous example we want to know what land cover is in each watershed. In this case our Intersect theme is the theme that shows the land cover. The Overlay theme is the theme that contains the watershed boundaries. The Intersect Button produces a polygon shapefile where the polygons or lines represent the combinations of the two input shapefiles. In the example the output polygons would be combinations of watershed and land cover. Thus, each polygon or line would have fields that identify the polygon s watershed and land cover. An Intersect is kind of like a Clip but with two main differences: 1) the output file consists of only the geographic area common to both themes. Any features outside of the intersection are not included in the output file 2) The output theme attribute table contains the fields from both the Intersect theme and the Overlay theme Page 19

20 An Example INTERSECT Building on the example we did for the CLIP command let s say we wanted to determine the distribution of Pre-Settlement Vegetation within the Watershed Basins in Crow Wing county. You have a shapefile that shows the Pre-Settlement Vegetation and one that shows the watershed basins in Crow Wing County. What you want is a theme that shows the Intersection of these two pieces of information. Below are snapshots of the two themes we will use in this analysis. In this case the Pre-Settlement Vegetation theme is the Intersect theme and the Watershed Basin theme is the Overlay theme. Pre-Settlement Vegetation The Intersect Theme Watershed Basins The Overlay Theme Page 20

21 An Example INTERSECT INTERSECT Button Step 1 - Press the INTERSECT Button Once you have the themes of interest on the View press the INTERSECT button on the ArcView Utilities form. If it is not open use the WINDOW: Show ArcView Utility Tools option to open it. Step 2 - Select the Intersect Theme You will then be prompted to select the Intersect Theme from a list of polygon or line themes in the currently active View document. In this case the Pre-Settlement Vegetation theme is our Intersect Theme. Page 21

22 An Example INTERSECT Step 3 - Select the Overlay Theme Now you will be prompted to enter the Overlay theme from a list of the Polygon themes in the currently active View. In this case our Overlay theme is the Watershed Basins theme. Step 4 - Enter a New Filename You will be requested for a new filename. The default filename is INTER.SHP. You can specify a new location and theme name if you wish. Once you enter a filename the two themes will be intersected and you will be prompted to add the new theme to a view. Page 22

23 An Example INTERSECT INTERSECT Results The snapshot above shows the resulting output. As you can see, there are lines that cross vegetation types. These are watershed boundaries. Below is part of the table where you can see that both the vegetation and watershed are part of the theme attribute table. Page 23

24 This page intentionally left blank. Page 24

25 The MERGE Button Why MERGE? The MERGE button allows the user to merge (append) physically separate shapefiles, of the same theme but different areas, into a single shapefile. In conventional terms this is equivalent to taking two quad maps, trimming the edges with a scissors, aligning the two map sheets and taping them together, except that it s done in the computer and the maps, scissors and tape you are using are silicon based. Merging themes is useful when you have a theme that is organized geographically (by county or quad for example), and you need to analyze two or more geographic units (tiles). If you wanted to look at the wetlands for two adjacent counties you might want to join them together so that statistics are easier to create. Another common reason for merging shapefiles is when you have many tiles you want to examine. By merging the files together you only have to deal with one theme instead of one theme for every tile. What do I Need to MERGE? Merge requires that you have two or more themes in a View that cover different areas and represent the same data layer. That is, you could merge two adjacent townships of forest inventory data but you could not merge a township of soils with an adjacent township of forestry data. The themes that you are merging should have the same attributes and represent different spatial extents. What does MERGE Produce? The MERGE command produces a new shapefile that contains the contents of the input files. All tile borders will remain. Page 25

26 An Example MERGE While working on a project you realize that you need some wetland information. Digging into this problem you find out that you can get your hands on some National Wetlands Inventory data that is stored based on the USGS 1:24,000 quad tiling system. You re working in an area that includes two 1:24,000 scale quads, Coon Lake Beach and Linwood. The data sets are shown below. Coon Lake Beach Quadrangle Linwood Quadrangle You want to be able to calculate accurate areas and work on these two files and would prefer that they are a single file for convenience and to reduce the complexity of your ArcView project. This is a job for the MERGE command. Page 26

27 An Example MERGE MERGE Button Step 1 - Press the MERGE Button Once you have the themes of interest on the View press the MERGE button on the ArcView Utilities form. If it is not open use the WINDOW: Show ArcView Utility Tools option to open it. Step 2 - Select the Themes to be MERGEd You will then be prompted to select the theme to merge from a list of themes in the View. As you can MERGE many themes you will be presented with the prompt many times. In this case we will be selecting the LINWOOD NWI data to be the first theme to MERGE. Page 27

28 An Example MERGE Step 2 - Select the Themes to be MERGEd Keep selecting files until you have entered all desired themes. You will notice that as you select themes they will be removed from the list. If you are done selecting themes then press the Cancel button. Step 3 - Enter a new Filename Once you have selected the themes you are interested in and pressed the Cancel button you will be requested to enter a new filename. The program will crunch the numbers and merge the files you are interested in. Once complete, you will be asked to add the theme to a view and you re done! The output results are shown below with the quad boundaries shown for visual context. Page 28

29 The ERASE Button Why ERASE? The ERASE button allows the user to erase features in the input theme based on a set of polygons in another theme. This is equivalent to masking out the features in areas that are not needed for a specific analysis. ERASE is conceptually opposite of what the CLIP command performs. In the CLIP command the output features are those that are inside the polygons of interest. In ERASE, the output features are those that are outside the polygons of interest. When you erase features you are removing features that fall within the input polygons by clipping them at the edges. This is important in cases where you want to consider the area of the features in one theme but exclude those areas that are in another theme. For example, if you wanted to create a map that shows population density per square mile, you may want to consider those areas that can support population. You could use the ERASE command to remove the water features from a shapefile that contains population information. After all, you can t build and live on water so why should be consider it in our population density calculations? What do I Need to ERASE? What does ERASE Produce? ERASE requires a point, line or polygon theme (the Input Theme) that contains the features you want to erase and a polygon theme (the Erase Theme) that contains the areas you wish to erase the features in the input theme. ERASE produces a new shape theme that contains the features from the Input theme that are outside of the polygons in the Erase theme. Page 29

30 An Example ERASE Let s say that you wanted to create a population density map for a particular area and that you only wanted to consider that area that was upland (not water or wetlands) in the density calculations. You have a polygon shapefile that displays the cities, towns, and townships with population information in the feature attribute table and a polygon shapefile that shows wetlands and water bodies. Using the ERASE command you can remove the area of the wetlands and water bodies from the cities and townships shapefile. By then using the remaining upland area a more appropriate value of population density can be calculated. Cities and Townships (the Input Theme) Wetlands and Water Bodies (the Erase Theme) Page 30

31 An Example ERASE ERASE Button Step 1 - Press the ERASE Button Start the process by making sure that your themes of interest are on the View and then press the ERASE button in the ArcView Utilities Form. Step 2 - Select the Input Theme The next step is to select the theme whose features you wish to erase. In this case the Input theme is the theme that contains the City and Township Polygons. Step 3 - Select the Erase Theme Now select the theme that contains the features you want to use to erase features from the Input theme. This must be a polygon theme. Page 31

32 An Example ERASE Step 4 - Specify an Output Filename You will be then requested to enter a new name for the output shapefile. Once a name is entered, press the OK button and the program will proceed to perform the ERASE. Once the ERASE is complete the new theme will be added to the View. The following graphic shows the results of the ERASE command. As you can see areas within the theme that were coincident with water features have been removed. Page 32

33 The UNION Button Why UNION? What do I Need to UNION? What does UNION Produce? The union Button is used to perform a spatial overlay of two themes to determine the spatial coincidence of the features in the themes. Union is useful when you want to look at one mapped variable in relation to another mapped variable. A fisheries manager may want to know what the land cover is in each watershed in their management area to determine if there is any relationship between the land cover types and the water quality of the lakes in a watershed. The union command is the way to get the job done. The union process requires two themes as input. A Union Theme which must be a polygon theme, and an Overlay Theme which must be a polygon theme. In the previous example we want to know what land cover is in each watershed. In this case our union theme is the theme that shows the land cover. The Overlay theme is the theme that contains the watershed boundaries. The Union Button produces a polygon shapefile where the polygons or lines represent the combinations of the two input shapefiles. In the example the output polygons would be combinations of watershed and land cover. Thus, each polygon or line would have fields that identify the polygon s watershed and land cover. An Union is much like an Intersect except that the output contains all polygons in both files whether they overlap or not. The output file contains all the polygons of the two input files. Page 33

34 An Example UNION Building on the example we did for the CLIP command let s say we wanted to determine the distribution of Pre-Settlement Vegetation within the Watershed Basins in Crow Wing county. You have a shapefile that shows the Pre-Settlement Vegetation and one that shows the watershed basins in Crow Wing County. What you want is a theme that shows the Intersection of these two pieces of information. Below are snapshots of the two themes we will use in this analysis. In this case the Pre-Settlement Vegetation theme is the Union theme and the Watershed Basin theme is the Overlay theme. Pre-Settlement Vegetation The Intersect Theme Watershed Basins The Overlay Theme Page 34

35 An Example UNION Step 1 - Press the UNION Button Step 2 - Select the Union Theme UNION Button Once you have the themes of interest on the View press the UNION button on the ArcView Utilities form. If it is not open use the WINDOW: Show ArcView Utility Tools option to open it. You will then be prompted to select the Union Theme from a list of polygon themes in the currently active View document. In this case the Pre-Settlement Vegetation theme is our Union Theme. Step 3 - Select Union Theme Output Fields Now specify which attributes you want to carry from the Union theme to the output theme. NOTE: The more fields you select, the longer the process will take. Page 35

36 An Example UNION Step 4 - Select the Overlay Theme Now you will be prompted to enter the Overlay theme from a list of the Polygon themes in the currently active View. In this case our Overlay theme is the Watershed Basins theme. Step 5 - Select Overlay Theme Output Fields Now specify which attributes you want to carry from the Overlay theme to the output theme. NOTE: The more fields you select, the longer the process will take. Step 6 - Enter a New Filename You will be requested for a new filename. The default filename is THEME1.SHP. You can specify a new location and theme name if you wish. Once you enter a filename the two themes will be Unioned and you will be prompted to add the new theme to a view. Page 36

37 An Example UNION UNION Results The snapshot above shows the resulting output. As you can see, there are lines that cross vegetation types. These are watershed boundaries. Below is part of the table where you can see that both the vegetation and watershed are part of the theme attribute table. Page 37

38 This page intentionally left blank. Page 38

39 The SUBSET LEGEND Button Why SUBSET a Legend? What do I Need to SUBSET a LEGEND? What does SUBSET LEGEND Produce? The SUBSET LEGEND button is used to reduce a theme s legend classes to those classes that exist in the current theme. Each class in the legend is compared to a list of valid values in the current theme. If the legend class does not have an associated value in the theme then it (the legend class) is removed from the theme s legend. Saved legends are an efficient way to distribute legend information that may be used over and over. These saved legends, often called, Global legends typically contain the entire range of valid values for a particular field in a data set. Often times, you will be working in a smaller area that may only contain a subset of these values. When that happens you have classes in your legend that don t show up in your map. This can lead to confusion and difficulty interpreting the map. To subset a legend you only need to have a theme with a UNIQUE legend that may or may not have more classes than you need. These are often created by Loading a legend or by using the Theme Catalog utilities. The SUBSET LEGEND command produces a theme with a legend that matches the data in the theme. That is, there are no extra classes in the new theme legend. This increases the readability of the legend and makes them easier to interpret. Page 39

40 An Example SUBSET LEGEND Step 1 - Load a Theme and a Legend Let s assume that you are working on a shapefile of Ramsey County Pre-Settlement vegetation that was extracted from a statewide data set. When the CLIP operation was complete you were left with a legend that contained all of the possible landcover classes throughout the state. In fact, there are18 different landcover classes throughout the state and only seven in Ramsey County and you would like the legend to reflect the contents of the file. Ramsey County Page 40

41 An Example SUBSET LEGEND SUBSET LEGEND Button Step 2 - Press the SUBSET LEGEND Button Once you have the theme and legend of interest on the View press the SUBSET LEGEND button on the ArcView Utilities form. If it is not open use the WINDOW: Show ArcView Utility Tools option to open it. The legend of the currently active theme will be subset. Any classes found in the theme that are not found in the legend will be assigned to a unique class as Unknown and given a default color. SUBSET LEGEND Results Ramsey County Page 41

42 This page intentionally left blank. Page 42

43 The UPDATE AREA, PERIMETER and LENGTH Button The UPDATE AREA, PERIMETER, and LENGTH button allows the user calculate feature geometry (i.e. area, length etc) for each feature (lines and polygons) in a theme. This command works on the feature attribute table of a theme and then goes through each features and calculates the following feature geometry values: Polygons: Area - the area of a polygon in native coordinate units. Perimeter - The perimeter length of the polygon in native coordinate units. Acres - the area in acres (assuming the native coordinates are in UTM meters). PerFeet - The perimeter length of the polygon in feet (assuming the native coordinates are in UTM meters). Lines: Length - The length of a line segment in native coordinate units. Lfeet - The length of a line segment in feet (assuming the native coordinates are in UTM meters). Why UPDATE? What do I Need to UPDATE? What does UPDATE Produce? ArcView does not manage any feature geometry values when features are created or edited as does Arc/Info. If you are using an Arc/Info coverage, export it to a shapefile and then add some features, the new features will not have any feature geometry values (length, perimeter or area). In this case you can use this button to update the values. The UPDATE command requires a shapefile or coverage with lines or polygons to be in the currently active View document. UPDATE simply adds the fields, if necessary, and calculates the feature geometry values for the features as the currently exist. It the fields already exist, they are updated. Page 43

44 An Example UPDATE AREA, PERIMETER and LENGTH Let s assume that you have received theme, with polygons, from a contractor who created these polygons by interpreting things from an air photo and capturing them using heads-up digitizing in Arc/Info. The coordinate system is UTM so the coordinate units are meters. While Arc/Info manages the feature attributes (perimeter and area) you would like to know the acreage of each polygon and their perimeter in feet rather than meters. UPDATE AREA, PERIMETER and LENGTH Button Step 1 - Press the UPDATE AREA, PERIMETER and LENGTH Button Step 2 - Select the Theme of Interest Once you have added the theme to the currently active View document, the first step is to press the UPDATE AREA, PERIMETER and LENGTH button. You will be presented with a dialog box that shows a list of themes in the currently active View. Select the theme of interest and the computer will crunch away and perform the necessary calculations. View the results by opening the Theme attribute table for the theme you just converted and examining the new or updated fields. Page 44

45 The SHIFT COORDINATES Button Why SHIFT COORDINATES? What do I Need to SHIFT COORDINATES? What does SHIFT COORDINATES Produce? The SHIFT Form The SHIFT COORDINATES button allows the user to shift the X and/or Y coordinates of features in a theme by a user specified amount. This command leads to a dialog box that allows the user to enter the shift values by hand, or to apply some standard shift values that are specific to Minnesota. Sometimes it is necessary to apply a shift to coordinates in a shapefile or coverage. In this case, the shift command was produced to help individuals shift or un-shift data based on the Minnesota 4.7 million meter shift or those who wish to shift their datum from NAD27 to NAD83 although it is flexible enough to allow users to enter in their own shift values To use the SHIFT COORDINATES command all you need is a active theme on the current View document. The SHIFT command does not work on Image themes, only Feature based themes (point, line, or polygon) which can be either shapefiles or Arc/Info coverages. SHIFT COORDINATES will create a new shapefile from an old shapefile applying the shift to each of the features in the input theme. No attributes or other entities will be modified in any way. The shift forms is where you enter the amount of X and Y shift you want to apply to the coordinates in the theme Page 45

46 The SHIFT COORDINATES Button What is the Minnesota Y- SHIFT? The Minnesota Y-Shift of -4.7 million meters was developed during the time when some GIS software could not deal with doubleprecision coordinate values. In the case of UTM coordinates, the Y coordinate is a double precision number. A shift of -4.7 million brought the Y values below 999,999 which is a single precision number. The DNR s standard for coordinate system is Un-Shifted UTM values. You may, however, encounter data files that may still be in shifted coordinates and need to be unshifted to meet the departmental standard. The Y-Shift value defaults to a positive 4,700,000 meters for Unshifting data that has been shifted. If you want to SHIFT data, that is, subtract 4,700,000 meters then simply add a minus sign (-), before the value. Page 46

47 The SHIFT COORDINATES Button What is the NAD27 to NAD83 SHIFT? For many years geographic data was collected and referenced to the North American Datum of 1927 (NAD27). In 1983, the USGS produced a new datum, the North American Datum of Because of improved instrumentation and technology, the shape of the earth could be defined with greater accuracy. In Minnesota the datum shift averages 212 meters in the Y direction and -15 meters in the X direction. Because the NAD27 - NAD83 transformation is a coordinate shift rather than a projection change and that the Standard Deviation values for the X and Y shift is quite small (2 meters in the X and Y) it was determined that the average shift was adequate for most natural resource applications. The NAD shift values defaults to perform a shift from NAD27 to NAD83. If you wanted to shift the coordinates from NAD83 to NAD27 all you need to do is change the x-shift value to +15 and the y-shift value to -212 using the cursor and keyboard. Page 47

48 An Example SHIFT COORDINATES Step 1 - Make the Theme of Interest the Active Theme Let s assume that you have received an ArcView Shapefile from a colleague for a project that you are working on and the shapefile happened to be in shifted coordinates. You knew that was the case because when you loaded the new theme into your existing View document it was no where to be seen and when you did find it, it was far to the south of Minnesota. To be able to effectively use this data set you need to Un-SHIFT the coordinates of the features in the theme. Start the Process by making the theme to be shifted the Active Theme by pressing on it s legend in the table of contents. Step 2 - Press the SHIFT COORDINATES Button SHIFT COORDINATES Button Page 48

49 An Example SHIFT COORDINATES The SHIFT COORDINATES dialog box will then appear. Step 3 - Enter the Coordinate Shift Value At this point you could use the mouse to place the cursor in the Y- Shift data entry box and type in the value of or you could use the mouse to check the box next to the Minnesota Y-Shift. Either way you ll end up with the same thing. Step 4 - Press the OK Button Once you have your shift values entered press the OK button. You will then be prompted to enter a new shapefile name, the machine will perform the shift, and then ask you whether or not you want to add the theme to a View. Page 49

50 This page intentionally left blank. Page 50

51 The MULTI-POINT to POINT Button The MULTI-POINT to POINT button is used to convert a multi-point shape theme into a point shape theme Multi-point shape themes are commonly created by by adding the Labelpoint feature of an Arc/Info polygon coverage. Why convert MULTI-POINTS to POINTS? What do I Need to Convert MULTI- POINTS to POINTS? The primary reason for converting from a multi-point theme to a point theme is because a multi-point theme cannot be edited by the user. If you have a theme that is multi-point and you wanted to move the shapes, you could not. You would first have to convert them to points. A Multi-Point theme. You can determine the shape type by opening the table of a theme and viewing the SHAPE field. What does MULTI-POINT to POINT Produce? The MULTI-POINT to POINT command produces a new shapefile where the shapes are converted from multi-points to point features. Page 51

52 An Example MULTI-POINT to POINT If you were making a small scale map that showed, among other. things, the locations of cities in the state you probably would want to display the city locations as points rather than as polygons. You could do this by using the labelpoint features from the appropriate polygon coverage that shows city locations. In this case you would want to make sure that the city point locations fall at the intersection of the major roads that go through the city. Using the polygon labelpoints you cannot be assured that they would fall in the correct location. In this case you might like to move the point locations so that they fall exactly on the road intersections but because this is a Multi-Point theme you cannot edit the point locations. The following graphic shows an example. Look at the attribute table and notice the values of the field SHAPE. They are MultiPoint. Page 52

53 An Example MULTI-POINT to POINT. To edit the locations of these points you will first need to convert the theme to a Point theme using the MULTI-POINT to POINT command. Step 1 - Make the Theme of Interest the Active Theme Step 2 - Press the MULTI- POINT to POINT Button The MULTI-POINT to POINT command works on the active theme, so make the theme of interest the active theme. Once you have a theme active then press the MULTI-POINT to POINT button on the ArcView Utilities toolbar. MULTI-POINT to POINT Button Step 3 - Enter a new Shapefile name Once you have selected the button you will be prompted to enter a name for the new shapefile. Once you enter the new name the computer will proceed to convert the multipoint shapes in the file to point shapes in the new file. Page 53

54 An Example MULTI-POINT to POINT. Once the conversion is complete, the theme will be added to the active view and you can proceed to edit and move the points as you wish. Notice the SHAPE field in the table, the values are now POINT rather than MultiPoint. Page 54

55 The UNGROUP POLYGONS Button The UNGROUP POLYGONS button is used to ungroup a multipolygon feature into a set of single polygon features. Multi-polygon features are often referred to as Regions and consist of one or more polygons that are attached to a single record in the theme attribute table. Themes with multi-polygon features are commonly created by the Buffer Command or when using the Summarize functionality of ArcView when merging shapes with similar field values. Why UNGROUP? What do I Need to UNGROUP? What does UNGROUP Produce? Ungrouping polygons is most often used when the user needs to consider each polygon individually. For example, if a user wanted to know the area of each individual polygon of a multi-polygon feature, they would first have to UNGROUP them. A Polygon theme with multi-polygon shapes. UNGROUP Polygons modifies the original shapefile so that each individual polygon has an associated single record in the theme attribute table. It does not create a new shapefile! If you need to retain the original version of the shapefile, make a copy of it. Page 55

56 An Example UNGROUP POLYGONS As part of a wetland study you created a buffer around a set of. selected wetlands that are not contiguous. When the Buffer command encounters buffer features that are separate, it creates buffers around each feature and the output buffers are considered a Multi-Polygon feature. The following graphic shows the buffer and the theme attribute table. As you can see, there is many buffer polygons but only one record in the attribute table. Step 1 - Make the Theme of Interest the Active Theme The UNGROUP POLYGON command works on the active theme so make the theme of interest active by pressing on it s legend in the table of contents. Step 2 - Press the UNGROUP POLYGONS Button UNGROUP POLYGONS Button Page 56

57 An Example UNGROUP POLYGONS. Once initiated, the UNGROUP POLYGONS command will then proceed through each multi-part polygon, separate the polygons and create a database record for each polygon as shown in the following graphic. Page 57

58 This page intentionally left blank. Page 58

59 Appendix A: Installation of ArcView Extensions The installation of the ArcView Utilities extensions requires two. files: TOOLS_DD.AVX - the Utilities extensions AVDLOG.DLL - Dialog Designer Extension DLL AVDLOG.DAT - Dialog Designer resource file This ArcView Extension can be installed in one of two locations. By default, ArcView looks in the $AVHOME/EXT32 subdirectory (on Windows 95 and Windows NT machines) or the $AVHOME\EXT16 subdirectory (on Windows 3.1 machines) where $AVHOME is usually \esri\av_gis30\arcview. This is where the standard distribution extensions can be found. ArcView also will look in a subdirectory for extensions as referenced by an environment variable USEREXT. This variable is reserved for a location where user developed extensions can be stored. To install this extension is easy. Decide where you want the extension to reside (either the default or user defined Extension locations) and then copy the file TOOLS_DD.AVX to that location. The next time you open ArcView and access the Extensions Dialog you will see the extension appear. As this extension relies on the Dialog Designer extension you must have the extension available to you. If you do not have the extension installed simply copy the file AVDLOG.DLL to the $AVHOME/lib32 or $AVHOME/lib16 subdirectory. Then copy the AVDLOG.DAT file to the $AVHOME/lib32 or $AVHOME/LIB16 subdirectory. You will then be able to load the extension within ArcView. Page 59

60 Appendix A: Installation of ArcView Extensions Please refer all questions, comments and suggestions to:. Tim Loesch GIS Applications Programmer Minnesota Department of Natural Resources 500 Lafayette Road, Box 11 St. Paul, MN (612) Page 60