SPATIAL DATA EDITING
SPATIAL DATA EDITING
This chapter is intended to perform editing of pre-existing maps. Maps can be in the form of shp or non-shp data such as CAD, GPS or kml. If the data owned is not shp, then data conversion must be done first. The shp data is then identified for its appearance on satellite imagery. If there are geometric errors, then in this chapter several features have been described in the ArcMap application that can be used for editing shp data.
Convert Data to Shapefile (shp)
Geographic Information System data can be sourced from non-shp data, such as: Global Positioning System (GPS) data, digitized data on Google Earth and data from Ms. Excel. To be able to use these data in ArcGIS applications, users need to convert data.
CAD Data Conversion (dwg)
There are two ways that can be used to convert dwg formatted data into shp data. The first method is data cleansing, which is basically done to identify and delete unnecessary layers in the CAD file. This method is highly recommended if the existing data has an irregular layer. However, this method certainly requires AutoCAD software in the process. It is different with the Select Attribute method which only uses ArcMap software. The Select Attribute method is easier because it is done only by selecting the required layers (irrigation areas and irrigation networks) using the Select by Attribute feature in ArcMap.
a. Cleansing Data Method in AutoCAD
To reduce data editing work in ArcMap, before we convert data from drawing (dwg) to shapefile (shp), then do data cleansing in AutoCad, with the following steps:
1. Open the AutoCad application, activate the Standard toolbar and the Layers toolbar from the View menu Toolbars. Open dwg format data using Open select the Model tab
2. Clean block, style text by typing Purge command in command line Click Enter Purge All Purge All Item
3. Click on Layer Properties Manager, right click Select All, click on the sign to turn off all layers.
4. Identify the layers one by one by reviving each layer. Layer images that do not show the presence of irrigation networks or irrigation areas can be turned off again.
5. Check the data layers that appear to have an overview of irrigation networks and irrigation areas, if there are layers that are still combined with each other or if there are separate irrigation areas, move them into one layer of irrigation areas and irrigation networks. The trick is to select the network or irrigation area to which the layer will be transferred. Click Layer Control in the Layers toolbar and then select the layer to be vectored. Separate irrigation building areas, irrigation canals, standard irrigation areas, potential irrigation areas and functional irrigation areas.
6. Block all vectors from the previously selected active layer Click Menubar Insert Write Block Specify file name, units in Meters and storage location OK.
7. Check the results by clicking Open open the block file that has been created. Checks whether the resulting coordinates are the same as the coordinates in the previous dwg file. If the same, then the file can be opened and converted to shp in ArcGIS software.
8. Click Add Data then browse the file that has been generated in the cleansing process double click on the file Select Point (for irrigation buildings), Polyline (for irrigation canals) and Polygon (for raw, potential and functional irrigation areas) Add
9. Right-click the layer that appears Data Export Data browse the file storage location specify
the name and type of output file to Shapefile Save click Yes to display the resulting shp output.
b. Select Attribute Method in ArcMap
1. Open the ArcMap application in the Windows Start Menu. Start ArcGIS ArcMap .
2. If a dialog appears (ArcMap - Getting Started) it can be ignored by clicking Cancel.
3. Enter data by clicking Add Data in the Standard toolbar.
Add Data can also be done by right-clicking Layers on the Table of Contents
️Add Data
4. Browse the data in dwg format double click the dwg file to bring up the irrigation area, select polygons, for channels, select polylines and points for buildings.
️ click Add.
5. Right-click the polygon/polyline/point layer Open Attribute Table click
Table Options click Select By Attributes.
6. Select the “Layer” field by double-clicking the field name until its name appears in the box below click = select a layer name that describes the irrigation area (in the example it is named “Zero 3”) click Apply. The layer with the selected name will be highlighted.
7. Right click the layer Data Export Data Make sure the selected Export is Selected features browse the storage location specify a name and Save as type as Shapefile click Save click OK the file will be automatically added to the layer.
Notes:
It should be noted that this method can be used if the layers in the CAD data are neatly arranged, where there are no similar layers that are separated from other layers or vice versa there are layers of different types joined in the same layer or even certain styles of AutoCAD that are still included in the in layers.
GPS Data Conversion
Data from GPS is usually stored in GPX format. GPS files can be used to describe waypoints, routes and tracks. In order for a GPX file to be read by ArcGIS, it must first be converted into a shapefile format with the following steps:
1. Open ArcGIS Programs ArcMap.
2. Click the Search thumbnail on the right Menu Bar, type GPX. Select GPX To Features (Conversion). GPX to Features can also be selected from ArcToolBox on the Right Menu Bar Conversion Tools From GPS
Google Earth Data Conversion
Today, the Google Earth application can help with the needs of mapping and finding specific locations. Mapping data in the Google Earth application (kml or kmz) can be converted into ArcGIS format data (shapefile) with the following steps:
1. Prepare the google earth results file, as shown below.
2. Save the irrigation area layer in .kml . format
3. Open ArcMap. Activate ArcToolbox on the Right Menu Bar Conversion Tools
From KML KML To Layer
4. Enter the file format kml or kmz as input, specify the location of the output storage folder and finally fill in the layer name in the Output Data column Click OK
5. The results will be displayed in ArcMap as a Layer.
Spreadsheet Data Conversion (Excel)
Spatial data from GPS can be edited using MS. Excel to add other complementary data. Data that can be converted into shapfiles in particular are coordinate data, more specifically the coordinates of irrigation buildings or special points obtained during surveys. The steps are as follows:
1. Open a spreadsheet (excel) file in xls or xlsx format using the Ms application. Excel or other application relevant to the file format.
2. Provide clear column names, such as X, Y, names, and other important additional information, for example to provide an explanation of the position of the Irrigation Building (certain primary or secondary channels).
3. Then Right Click the Layer symbol, several menu options will appear, then click Add Data.Select the Excel file Click Add. Select the desired worksheet
️ Click Add
4. Right click on data Open, tabular data will appear. Make sure the data is correct before converting
5. Close the tabular data table window. Right Click on the data layer in the Table of Content
>> click Display XY Data .
6. Enter X for column X and Y for column Y, set the projection coordinates by Clicking the Edit button Select Select Geographic Coordinat System World select WGS 1984. The distribution of these coordinates will appear in the Table of Contents.
Notes:
It should be noted that this is only a display, not a shapefile (*.shp) and still in the form of Events so it still requires a conversion process.
7. Convert the X,Y Data, Right Click Data Export Data, save it in the desired folder Specify a file name Select Save as type: Shapefile click Save.
Notes:
• Before converting data, make sure the coordinate format matches the coordinate system used in the entire map• If the coordinates are still in the form of Degrees-Minutes-Second (DMS), the minute and second coordinate data is converted to degrees, with a conversion value of 1 degree = 60 minutes = 3600 seconds. X is Longitude (0°-360°) and Y is Latitude (0°-90°), if Y is at south latitude, the value of Y becomes minus (-). We recommend that the coordinate value is set with 5 (five) digits behind the comma.• If the coordinates are taken in UTM format, in the Display XY Data stage, select the UTM coordinate system according to the zone, then convert the coordinate system using the Projection feature which will be explained in Sub-Chapter 3.3.1. Data Identification: Coordinate System.
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