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--- tutorial:calculating_accumulated_cost_surface_and_least-cost_pathway [2013/08/14 14:52]
admin
+++ tutorial:calculating_accumulated_cost_surface_and_least-cost_pathway [2016/11/23 19:27]
isabella
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   * How to calculate a friction surface, cost surface and least-cost pathway
-  * Functors: \\ - //[[:Calc Cost map]]//\\ - //[[:Calc Pathway map]]//
+  * Functors: \\ - //[[:Calc Cost Map]]//\\ - //[[:Calc Pathway Map]]//
 This exercise requires the calculation of a friction surface, representing the relative cost of crossing a unit cell depending on the land use. We can express this surface both in terms of distance – no differential cost exits among types of land uses; hence the least-cost pathway will be the shortest route, i.e. the Euclidian distance – time, financial cost or some type of effort. Thus, this value is calculated in relation to some unit (time, transportation cost, etc).
@@ Line 66: / Line 66: @@
 \\
 \\
-Now place three //[[:Calculate Map]]// and four //[[:Number Map]]// functors, one within each //[[:Calculate Map]]// and two //[[:Number Map]]// functors within the third, and one //[[:Number Table]]// within one of the two first //[[:Calculate Map]]// functors and //[[:Save Map]]//. Open //[[:Number Map]]//, assign a unique number (1 and 2) to each one and assign "1" to //[[:Number Table]]//. Finally connect Map ''landuse.tif'' to //[[:Number Map]]// 1 and Map ''slope.tif'' to //[[:Number Map]]// 2 of the two first //[[:Calculate Map]]//. Then, connect the two first to the third //[[:Calculate Map]]// and it to //[[:Save Map]]//. Open //[:Save Map]]// and enter ''friction.tif''. This is what you get.
+Now place three //[[:Calculate Map]]// and four //[[:Number Map]]// functors, one within each //[[:Calculate Map]]// and two //[[:Number Map]]// functors within the third, and one //[[:Number Table]]// within one of the two first //[[:Calculate Map]]// functors and //[[:Save Map]]//. Open //[[:Number Map]]//, assign a unique number (1 and 2) to each one and assign "1" to //[[:Number Table]]//. Finally connect Map ''landuse.tif'' to //[[:Number Map]]// 1 and Map ''slope.tif'' to //[[:Number Map]]// 2 of the two first //[[:Calculate Map]]//. Then, connect the two first to the third //[[:Calculate Map]]// and it to //[[:Save Map]]//. Open //[[:Save Map]]// and enter ''friction.tif''. This is what you get.
 {{ :tutorial:cost3.jpg |}}
@@ Line 115: / Line 115: @@
 </WRAP>\\
-The **Source** port will receive the Map ''railroad.tif'' and the friction map output by the third //[[:Calculate Map]]//. Turn on **Diagonals Cost More**. This will penalize the movement across diagonal cells. Set **Maximum Number of Passes** to “2”. Leave all other options untouched.{{ :tutorial:cost7.2.jpg |}}
+The **Source** port will receive the Map ''railroad.tif'' and the friction map output by the third //[[:Calculate Map]]//. Turn on **Diagonals Cost More**. This will penalize the movement across diagonal cells. Set **Maximum Number of Passes** to “2”. Leave all other options untouched.
-Open //[[:Calc Pathway Map]]// now with the Edit Functor Ports. Link Map ''town1.tif'' to the **Source** port <note tip>**TIP**: **Source**, in this case, also represents the destiny since the cost map was built from the existing railroad. Thus, this algorithm will search for the least-cost pathway from the source to the existing feature, i.e. the railroad.</note>
+Open //[[:Calc Pathway Map]]// now with the Edit Functor Ports.
-Link the map output from //[[:Calc Cost Map]]// to the port **Cost** and Map ''railroad.tif'' to **Network** (because it represents a linear feature network) and the output **Network** port to //Save Map//. {{ :tutorial:cost8.2.jpg |}}
+Link Map ''town1.tif'' to the **Source** port <note tip>**TIP**: **Source**, in this case, also represents the destiny since the cost map was built from the existing railroad. Thus, this algorithm will search for the least-cost pathway from the source to the existing feature, i.e. the railroad.</note>
+Link the map output from //[[:Calc Cost Map]]// to the port **Cost** and Map ''railroad.tif'' to **Network** (because it represents a linear feature network) and the output **Network** port to //[[:Save Map]]//. {{ :tutorial:cost8.2.jpg |}}
 Activate the option **Use Lottery** (this is an artifact that permits the model to solve the path when two or more local minima are found).\\
 \\
-{{ :tutorial:cost9.jpg?300|}}//[[:Calc Pathway Map]]// ignores cells with values equal or lesser than 0 or null cells. In turn //[[:Calc Cost Map]]// needs a network map with null cells representing non-features. Go to //[[:Load Categorical Map]] and open it with the Edit Functor. Press the flag **Null Value** and make sure **Use specific value** is set to “0”.\\
+{{ :tutorial:cost9.jpg?300|}}//[[:Calc Pathway Map]]// ignores cells with values equal or lesser than 0 or null cells. In turn //[[:Calc Cost Map]]// needs a network map with null cells representing non-features. Go to //[[:Load Categorical Map]]// and open it with the Edit Functor. Press the flag **Null Value** and make sure **Use specific value** is set to “0”.\\
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 \\
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-You may try to maximize the solution for the Calc Cost Map algorithm by setting the **Maximum Number of Passes** to “0”. Compare the time spent by this run and its resulting path with that of previous model? Did it make a big difference?\\
+You may try to maximize the solution for the //[[:Calc Cost Map]]// algorithm by setting the **Maximum Number of Passes** to “0”. Compare the time spent by this run and its resulting path with that of previous model? Did it make a big difference?\\
 \\
 This type of model can also be modified to develop simultaneously multiple paths. Open the model ''join_towns.egoml'' in lesson 4 folder.{{ :tutorial:cost12.jpg |}}