BUFFERING - Geo-Processing

BUFFERING 

 

  Zone of a specified distance around features. Buffers are useful for proximity analysis. 

 Now we are going to do a simple  task by using buffering, we are going to determine which areas in Colombo city are effected by mosquito, for this we need a assumption, therefore we will assume 250 meters around the breeding points effected by mosquito. (for this we need the breeding points of Colombo city, but you can use what ever data you have as your requirements, )

Steps -

1. Launch the ArcMap, normally in the Arcmap it does not automatically assign a units for the layer, for the Buffer projects it is better to use meters or you can use as your requirements. Therefore right-click on the Layers go to properties, then click the General tab and then set both Map units and Display units to Meters.

2. add data layer you are going to use,

3. Now we have to add the "Buffer Wizard Tool" for ArcMap tool bar. therefore go to
Customize > Customize mode > Command Tab > Tools > Buffer Wizard
then drag the wizard and drop in to any tool bar you like,  

4. Now we have to open the "Buffer Wizard" and then select "Breeding Point" as the feature of  a layer.

5.  Then assign the value for the "At a specified distance" as 250 m, make sure you have select units as meters,

 6. then next step follow as I have shown below,

7. Now you can see the your final result .

8. If you need you can add a colombo city layer, colombo road layer or what ever layer you need and then you can easily do the proximity analysis.

APPEND - Geo-Processing

APPEND

Combines two or more adjacent layers into a single layer 

 In simple terms combine two or more layers together in to a single layer.

Now we are going to Append two provinces in Sri Lanka,

Steps

1. Open ArcMap and add data you are going to use for this project,

2. Then you can go to "search" and find "Append" or ArcTool Box Window> Data Management Tool > General> Append,

 

3. Now we are going to append "Central" province with "North-Central" province,

4. Now you can see "North-Central" layer have appended the "Central1" layer,

DISSOLVE - GeoProcessing

DISSOLVE

Use the Dissolve process to remove boundaries or nodes between adjacent polygons or lines that have the same value for specific attributes.

In simple terms this will merge the polygons which contains the same attributes.

Now we are going to dissolve district of Sri Lanka in to Province of Sri Lanka, or you can use whatever dataset you like to use,

Steps,

1. Open ArcMap and add data you are going to use for this project, 

 2. Then right click on the layer you have added, and then select the "Open attribute table",

 

3. Now you can see the attributes of your layer, then you can get idea what field you have to use for the Dissolve to your output. 

 

 4.  Select "Dissolve" tool,

 5. Then you have to select what field you are going to Dissolve to get your output, in this example I have use "Province" field.

 

6. Now you can see Dissolve has completed as result taken as layer "Province" to the ArcMap,

CLIP - GeoProcessing

 

CLIP

Reduces the spatial extent of one layer based on the extend of another

In simple term "CLIP" use to extract data we need for specific area from another layer

Steps -

1. Open ArcMap and add two layers which you are going to use for this project. In here we are going to extract road map for the Western Province from the Sri Lankan road map.

2. In the Menu bar you can see the "Geoprocessing" , then in the drop down bar you can select "CLIP", (otherwise go to Analysis Tools >Extract > Clip)

3. Now we are going to extract road map for the "Western Province", for that we are use "Roads" layer, make sure that we have to use"Roads" layer as a Input feature and "Western Province" as a Clip feature and assign a location for output feature class. 

4. After clip you can see that you have extracted road map for "Western Province". 

5. Now you can use this layer as a separate layer for your future projects,

GEOPROCESSING

GEOPROCESSING

Geoprocessing allows you to analyze and combine layers in different  ways based on the spatial relationships among features. 

  

 Following are the operations in Geoprocessing, 

• Dissolve - Aggregates features in a single layer that have the same attribute values.
• Append - Combines two or more adjacent layers into a single layer.
• Clip - Reduces the spatial extent of one layer based on the extent of another.
• Intersect - Finds those features falling within the spatial extent common to two layers
• Union - Combines two polygon layers.
  

GEOREFERENCING

GEOREFERENCING

Converting a raster data-set from image space to a real-world coordinate system is called Geo-referencing.

1    How to Map Kml image in a location where we selected from the Google earth in to the ArcMap Layer?

Steps,

1.    Select a place you like from the Google Earth, and add a placemark where you need.

       

    2.  Then add another four placemark around your previous placemark (Practice 1), (make sure that you  can identify the placemark clearly in the future step)

    

3. Then left side of the google earth you can see “Places ”windo. In that window you have your placemark (1,2,3,4). Now u have to create a folder there and drag and drop those placemarks in to your folder.

(Just right cliking on the places window you can create a new folder)

4.       Then right click on your folder and save as kml file. 

5.      Then save the location you have selected in the Google Earth, if you are use Google Earth Pro you can select following resolutions, 

6. Now we have created Kml file, then we need get that Kml file in to ArcGIS for that open ArcMap.

7. First of all we have to change the “Projection” of the layer in to “Kandawala” (If you select a country except Sri Lanka then you have to select coordinating system according to selected country, otherwise you can select “WGS 1984”)

8.        In ArcMap select the “Windows” tool and from the drop down list select “Search ” option or Ctrl+F. then type “Kml to Layer”, then press Enter. 

9.      Now we have to add our Kml file in to the layer, therefore select Kml file and add it in to the layer and select the output location also.

10.       Then ArcMap will add  Kml file in to layer, if you have done it properly Arcmap will display a massage  and also you can see your Placemarks in the ArcMap, (you can select either KML or KMZ)

  

 11.  Now you have to change the projection of the added KML or KMZ file by using tool “Project”, because our KML file is in WGS 1984 coordinating system.   

12.    Then do following steps to add your placemarks in to the ArcMap,

•    Go to “Input dataset of Feature class” and select for search and select the file (It is in .gdb format) 

•                        Then select the “placemarks”

•           Then as we did earlier we have to change the coordinate system in to “Kandawala”,

13.   Now you can see two layer one is your previous placemarks which is on “WGS 1984” coordination system and your new placemarks which is in “Kandawala ” coordinating system. (You have to select the coordinating system according to the country that you captured  the placemarks)

14.    Now we have to add the Google image we saved in to ArcMap, therefore right click on the “Layers ” and select “Add data” of select the “+” in the tool bar, then select the saved Google Earth “jpg” image.

15.    Then you can see jpg image been taken in to layers, (if you can not see your image or placemarks, always right click on the particular layer and select “Zoom to Layer” )

 

(Once we have placemark which is in we assigned coordinate system , we have to remove or un-tick the other placemarks )

16.  Now we have to map the image with placemarks, for that we can use “add control points” tool,  (You can get this tool from Georeferencing tool bar, Go to customize /Toolbars/ Georeferencing)

17.  From our image placemark 1 have to map with placemark 1 in the ArcMap, same as for other placemarks have to map.

 18. After mapping all the placemarks then you can check the RMS error of your project. For that go to Georeferencing toolbar and go to “View Link Table”. Then you can see the “Total RMS Error” if your result is less than 1 it is in acceptable margin.

19.   Finally you have to update the Georeferencing, for that go to Georeferencing toolbar, go to Georeferencing and “Update Georeferencing”.