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fuzzy_gib2 [2016/04/01 09:06] – extern redigering 127.0.0.1fuzzy_gib2 [2016/04/05 12:25] Stefan Ene
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-KG2204 Exercise 1: Fuzzy Overlay +====== KG2204 Exercise 1: Fuzzy Overlay ====== 
-admin|2014/10/02 09:50:17+
  
 In this exercise, we want to identify areas that are both close to water and where it is a lot of forest nearby. There are multiple methods to achieve this in ArcMap. In this exercise, we want to identify areas that are both close to water and where it is a lot of forest nearby. There are multiple methods to achieve this in ArcMap.
  
-One simple way to do this is to use a tool to identify the areas close to water ((for example the buffer tool can be used) and another tool to find areas where it is a lot of forest nearby. When this is done, an overlay of those two layers show where areas that fulfill both those criteria are ((see below).+One simple way to do this is to use a tool to identify the areas close to water (for example the buffer tool can be used) and another tool to find areas where it is a lot of forest nearby. When this is done, an overlay of those two layers show where areas that fulfill both those criteria are (see below).
  
-[[image|Overlay with clearly defined borders|{UP}/bin_overlay.png]]+{{:bin_overlay.png|Overlay with clearly defined borders}}
  
 With this approach, the result is highly dependent on the limits that for example define the distance that separates the close from the not close areas.  With this approach, the result is highly dependent on the limits that for example define the distance that separates the close from the not close areas. 
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 To have a clearly defined distance limit is for example relevant in case there is a law telling how close to a lake you can build. But in some cases, it is better to have a more fuzzy definition of how close a lake has to be to be close. In this exercise we will use fuzzy overlay to be able to solve the problem without the need to define exact limits. To have a clearly defined distance limit is for example relevant in case there is a law telling how close to a lake you can build. But in some cases, it is better to have a more fuzzy definition of how close a lake has to be to be close. In this exercise we will use fuzzy overlay to be able to solve the problem without the need to define exact limits.
  
-[[image|Fuzzy overlay|{UP}/fuzzy_overlay.png]]+{{:fuzzy_overlay.png|Fuzzy overlay}}
  
 ==Get the Data== ==Get the Data==
  
-Go to [[http://maps.slu.se]]. Choose an area that include water ((the area should be approximately 4 % of the limit) and download Fastighetskartan as vector format.+Go to [[http://maps.slu.se]]. Choose an area that include water (the area should be approximately 4 % of the limit) and download Fastighetskartan as vector format.
 The data will be sent to the email you choose and you can save and extract the data at the computer. The data will be sent to the email you choose and you can save and extract the data at the computer.
  
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 Open ArcMap. Open ArcMap.
  
-Add the files ''mo'' ((including forest and open areas) and ''mv'' ((including water) from the downloaded data. The names are not really ''mo'' and ''mv'' but instead something more similar to: ''fastighetskartanVektor_MO_1302_epsg3006_polygon''+Add the files ''mo'' (including forest and open areas) and ''mv'' (including water) from the downloaded data. The names are not really ''mo'' and ''mv'' but instead something more similar to: ''fastighetskartanVektor_MO_1302_epsg3006_polygon''
  
 To add files: To add files:
  
-:File » Add Data+File Add Data
  
 You will now a create a study area of 30000 X 30000 meters. Click on  You will now a create a study area of 30000 X 30000 meters. Click on 
  
-:Customize » Toolbars » Draw+Customize » Toolbars » Draw
  
 In the toolbar that appears; click on the ''Rectangle'' tool to mark up the area you want to work with. Rightclick your rectangle, choose ''Properties'', and ''Size and Position''. Type 30,000 m for width and height in the Size and click ''OK''. Then go to  In the toolbar that appears; click on the ''Rectangle'' tool to mark up the area you want to work with. Rightclick your rectangle, choose ''Properties'', and ''Size and Position''. Type 30,000 m for width and height in the Size and click ''OK''. Then go to 
  
-:Drawing » Convert Graphics To Features+Drawing » Convert Graphics To Features
  
-Make sure the output file is saved in your folder ((D:\Undervisning_HumangeostudX\...) and name it ''studyarea''.+Make sure the output file is saved in your folder (D:\Undervisning_HumangeostudX\...) and name it ''studyarea''.
  
-To avoid border effects; create a buffer ((Geoprocessing » Buffer) of 1200 meters. Name it ''studyarea_buffer''.+To avoid border effects; create a buffer (Geoprocessing » Buffer) of 1200 meters. Name it ''studyarea_buffer''.
  
 ===Calculate the distance from water=== ===Calculate the distance from water===
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 First we want to create a raster layer were the pixels indicate the distance to the nearest water. This is done with the tool ''Euclidean Distance'': First we want to create a raster layer were the pixels indicate the distance to the nearest water. This is done with the tool ''Euclidean Distance'':
  
-:ArcToolbox » Spatial Analyst Tools » Distance » Euclidean Distance+ArcToolbox » Spatial Analyst Tools » Distance » Euclidean Distance
  
-((If ''Tool Not Licensed''? Customize » Extensions...)+(If ''Tool Not Licensed''? Customize » Extensions...)
  
-The input is the water ((mv) and give a name and location for the file that will be created. Also set the pixel size to 100 meters. Then click ''Environments ''. Under ''Processing Extent'', choose to have the same extent as layer studyarea_buffer. Click ''OK''.+The input is the water (mv) and give a name and location for the file that will be created. Also set the pixel size to 100 meters. Then click ''Environments ''. Under ''Processing Extent'', choose to have the same extent as layer studyarea_buffer. Click ''OK''.
  
-((((((Question 1: What does it mean when a pixel in the created euclidean distance layer have the value 1000?)))+Question 1: What does it mean when a pixel in the created euclidean distance layer have the value 1000?
  
 ===Convert forest from vector to binary raster=== ===Convert forest from vector to binary raster===
  
-The layer ''mo'' contain not only forest ((Lövskog and Barrskog) but also open areas. We are only interested in forest for this analysis. To select only the forest polygons, go to:+The layer ''mo'' contain not only forest (Lövskog and Barrskog) but also open areas. We are only interested in forest for this analysis. To select only the forest polygons, go to:
  
-:Selection » Select By Attributes+Selection Select By Attributes
  
 Select the layer and create an expression like: Select the layer and create an expression like:
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 The forest pixels in the raster image will have different values. We want all of them to be 1 and the non forest pixels to be 0 or NoData. Therefore we use the tool: The forest pixels in the raster image will have different values. We want all of them to be 1 and the non forest pixels to be 0 or NoData. Therefore we use the tool:
  
-:ArcToolbox » Spatial Analyst Tools » Reclass >> Reclassify+ArcToolbox » Spatial Analyst Tools » Reclass >> Reclassify
  
 One easy way to give all values the same value is to choose ''Classify'' and:  One easy way to give all values the same value is to choose ''Classify'' and: 
  
-:Classification » Method: Equal Interval+Classification » Method: Equal Interval
  
 Set the number of ''Classes'': to 1 Set the number of ''Classes'': to 1
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 For this we will use the tool ''Focal Statistics'' which is found in  For this we will use the tool ''Focal Statistics'' which is found in 
  
-:ArcToolbox » Spatial Analyst Tools » Neighborhood » Focal Statistics+ArcToolbox » Spatial Analyst Tools » Neighborhood » Focal Statistics
  
 ''Focal Statistics'' calculate statistics ((in our case we are interested in the '''SUM''') for the neighboring pixels ((in our case the pixels or cells inside a '''circular ''' area with the radius of '''10 pixels''') for each pixel. In the figure below, the pixel is given the value 50 because 50 pixles with the value 1 is found in the defined neighborhood. ''Focal Statistics'' calculate statistics ((in our case we are interested in the '''SUM''') for the neighboring pixels ((in our case the pixels or cells inside a '''circular ''' area with the radius of '''10 pixels''') for each pixel. In the figure below, the pixel is given the value 50 because 50 pixles with the value 1 is found in the defined neighborhood.
  
-[[neig.png]]+{{:neig.png}}
  
  
-((((((Question 2: What does it mean when a pixel in the focal statistics layer have the value 1?)))+Question 2: What does it mean when a pixel in the focal statistics layer have the value 1?
  
  
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 Now we have to do some pre processing. The tool ''Fuzzy Membership'' will use a "fuzzification algorithm" were the pixel values will be converted to numbers between 0 and 1, were 1 is the best according our criteria.  Now we have to do some pre processing. The tool ''Fuzzy Membership'' will use a "fuzzification algorithm" were the pixel values will be converted to numbers between 0 and 1, were 1 is the best according our criteria. 
  
-:ArcToolbox » Spatial Analyst Tools » Overlay » Fuzzy Membership+ArcToolbox » Spatial Analyst Tools » Overlay » Fuzzy Membership
  
  
-The layer with distance to water are suppose to be small and the layer with the amount of forest nearby are supposed to be large in our overlay. ((Read about different Membership types in the tool help window, so that you can explain what it does.)+The layer with distance to water are suppose to be small and the layer with the amount of forest nearby are supposed to be large in our overlay. (Read about different Membership types in the tool help window, so that you can explain what it does.)
  
  
-((((((Question 3: What does it mean when a pixel in the "fuzzificated" distance to water layer have the value 1?)))+Question 3: What does it mean when a pixel in the "fuzzificated" distance to water layer have the value 1?
  
-((((((Question 4: What does it mean when a pixel in the "fuzzificated" amout of forest nearby layer have the value 1?)))+Question 4: What does it mean when a pixel in the "fuzzificated" amout of forest nearby layer have the value 1?
  
 ==Fuzzy Overlay== ==Fuzzy Overlay==
  
-The tool ''Fuzzy Overlay'' can be used to combine the two layers. Use ''Product'' for this ((this multiply the pixel values from the two layers).+The tool ''Fuzzy Overlay'' can be used to combine the two layers. Use ''Product'' for this (this multiply the pixel values from the two layers).
  
-:ArcToolbox » Spatial Analyst Tools » Overlay » Fuzzy Overlay+ArcToolbox » Spatial Analyst Tools » Overlay » Fuzzy Overlay
  
-((((((Question 5: What does it mean when a pixel in the fuzzy overlay layer have the value 1?)))+Question 5: What does it mean when a pixel in the fuzzy overlay layer have the value 1?
  
 When you are done, export the result using: When you are done, export the result using:
  
-:File » Export Map...+File Export Map...
  
 ==The End== ==The End==
  
-((((((Upload the answers to the five questions and the result from the fuzzy overlay as a jpeg to Mondo.)))+Upload the answers to the five questions and the result from the fuzzy overlay as a jpeg to Mondo.
  
 If you want to learn more about fuzzy overlay in ArcGIS, you can see this [[http://youtu.be/Hd13H0XO0LU|video]]. If you want to learn more about fuzzy overlay in ArcGIS, you can see this [[http://youtu.be/Hd13H0XO0LU|video]].
fuzzy_gib2.txt · Last modified: 2020/03/26 13:22 by Stefan Ene