Cost Path Analysis of Mars using SAGA

Purpose

The purpose of this tutorial is to learn the steps that will lead up to the creation of a Least Cost Path within the open source program known as SAGA, by applying several tools to a DEM (Digital Elevation Model) from Mars. The skill level required in GIS is intermediate, some skill level is required such as having to know what values you would require, plus what additional alterations are needed within different data set.

Objectives

The outcome after this tutorial is to know the tools that go into creating a least cost path analysis, such as point creations, Kriging, Terrain Analysis, Accumulation Cost, Reclassify and lastly Least Cost Path on a DEM that is imaging surfaces not of this world.

Introduction

SAGA is an open source program for GIS that has a lot of capability in Geoscientific analysis, it has been designed for effective implementation of spatial algorithms, and is constantly being updated with new features. One of the fields that hopefully will be growing soon, is the observation and analysis on surfaces not from Earth, in which testing if it is possible to do such a process using an open source program. For more information about SAGA you can visit their Homepage. Within this tutorial a cost path analysis will be done by using the Mars Rover Curiosity as the starting point, where it will travel along a route to two points, first a point of interest, and then its destination.

Methods

Uploading Data into Saga

The first step that is required is to upload a DEM into Saga, because this program has very specific file formats that it can handle, a previous tutorial will show how this is done. It can be found within Exploring Hydrological Analyses.

Creating Points

To create points on a layer, go into Geoprocessing>>Shapes>>Points>>Create Point Grid, this will bring up a window.

Save it to where your files are, click okay and a new shape layer will be created within your data window, within that window right click on the "Point Grid" and go into edit and "add shape".

Using the action tool , then create points by selecting the location on the map, then right click and click edit selected shape, and apply the changes. To create multiple points right click and add shapes.

Kriging

To be able to add the points to a grid layer, Ordinary Kriging will be done. For the uses of different Kriging methods the information can be found at Full Module Index

by going into Geoprocessing>>Spatial and Geostatistics>>Kriging>>Without Variogram Fit>>Ordinary Kriging.

This window should appear; add the point grid created in the "Points" section, also change target grid to "Grid System". Click okay and another window should appear.

Select the appropriate grid system and select okay and an image should appear.

Terrain Analysis

The terrain analysis within Saga has a simple met

Conclusion

This tutorial showed the basic steps that are needed to perform a cost path analysis, but due to issues with the Coordinate systems within SAGA, where planetary bodies such as Mars have yet to be given a Projected Coordinate system this processes could not be accomplished. This does leave room for more updates to be installed and possibly an update package that can include more processes for other worlds, such as change coordinate systems, measure distances with existing Coordinate systems. Other than that this program offered simple and effective method of terrain analysis, and Kriging Points to a surface.

Refernces

Sohail Dham and Colin Doucette. Exploring Hydrological Analyses, http://gracilis.carleton.ca/CUOSGwiki/index.php/Exploring_Hydrological_Analyses_using_SAGA_GIS/

Saga Library website, http://www.saga-gis.org/saga_module_doc/2.1.3/a2z.html

Saga Cost Path, http://sourceforge.net/projects/saga-gis/files/SAGA%20-%20Documentation/Tutorials/Least_Cost_Path_Analysis_Tutorial/

Kim Cimmery(2013),Tutorial: Using SAGA for Least Cost Path Analysis,http://download2.polytechnic.edu.na/pub4/sourceforge/s/sa/saga-gis/SAGA%20-%20Documentation/Tutorials/Least_Cost_Path_Analysis_Tutorial/LCPAtutorial.pdf