Spatial Analysis
Objectives:
Find the most suitable potential site for a new school, taking into consideration slope of the land, proximity to current schools and recreation centres.
Find the most suitable potential site for a new school, taking into consideration slope of the land, proximity to current schools and recreation centres.
Model Building
I am able to create a new geodatabase to hold and organise result data. This allows GIS data to be stored in a central location for easy access and management.
I can also use Model Builder to take input datasets and derive certain output criteria. Models are workflows that take sequences of geoprocessing tools, using the output of one tool and putting it into another tool as input (ArcGIS Resource centre). (fig. 1)
By reclassifying the outputs with a common scale, it is possible to weight the datasets to specific percentages of influence and combine this data to produce a map which displays areas of suitability.
Using a model allows certain aspects of the data to be tweaked to produce different maps for comparison, depending on the criteria required.
- A draw back of model builder is that if there is a link in the chain that is not correct and errors are produced when the model is run, it is difficult to fix it without starting from the beginning. Once the model is correct however, it can be used for numerous maps and analysis, saving a lot of time.
By reclassifying the outputs with a common scale, it is possible to weight the datasets to specific percentages of influence and combine this data to produce a map which displays areas of suitability.
Using a model allows certain aspects of the data to be tweaked to produce different maps for comparison, depending on the criteria required.
- A draw back of model builder is that if there is a link in the chain that is not correct and errors are produced when the model is run, it is difficult to fix it without starting from the beginning. Once the model is correct however, it can be used for numerous maps and analysis, saving a lot of time.
Figure 2
Spatial Analyst
Other Applications of Spatial Analyst and Model Builder
Spatial analyst can be used to create Digital Elevation Models (DEM), terrain and visibility modeling, for human geography to map population and crime, and for physical process mapping including surface run off modeling.
Spatial analyst can be used to create Digital Elevation Models (DEM), terrain and visibility modeling, for human geography to map population and crime, and for physical process mapping including surface run off modeling.
Mapping Skills
Hill Shade
I am able to input a hill shade and alter the transparency of layers to represent elevation on the map. This is a shaded relief raster created by using an elevation raster and setting an illumination source. The above example uses an azimuth of 315 degrees and altitude of 45 degrees above the horizon. When displayed under other layers with transparency of approximately 30% it gives a vivid impression of the terrain.
Colour Ramp
I have made use of a colour ramp to demonstrate visually, areas of increasing compatibility with the factors determined in the model.
Selection of data
By only displaying 4 intervals of suitability, it is visibly clearer which areas of the map are the best and the least suitable as land use for development of a new school.
I am able to input a hill shade and alter the transparency of layers to represent elevation on the map. This is a shaded relief raster created by using an elevation raster and setting an illumination source. The above example uses an azimuth of 315 degrees and altitude of 45 degrees above the horizon. When displayed under other layers with transparency of approximately 30% it gives a vivid impression of the terrain.
Colour Ramp
I have made use of a colour ramp to demonstrate visually, areas of increasing compatibility with the factors determined in the model.
Selection of data
By only displaying 4 intervals of suitability, it is visibly clearer which areas of the map are the best and the least suitable as land use for development of a new school.