Raster Data Analysis Flashcards
True or false:In analysis you can use one cell at a time or multiple cells at a time but the basis is always a cell
True
True or false: geoprocessing methods differ depending on data model.
True
There are 4 types of raster geoprocessing or operation
Local operations: the cells are analyzed individually without considering neighboutimg cells
Neighborhood operation: the target cell is considered along with its immediate neighboring cells to compute new values.
Extended neighborhood operations: extend the boundaries to consider a larger set of neighborhood cells.
Regional operations: this is where larger areas or zones , often defined by specific criteria are analyzed to compute statistics or identify patterns.
Give two local operations .
Reclassifying : conversion of cell values from one measurement to another .
Overlay: oldest map analysis to detect associations between two map layers . Different layers are integrated.
What are the three types of classification
Binary classification : creates a new raster containing 0 and 1.
Classification reduction : creates a new taste by grouping values into classes.
Classification ranking : assigns ranks to values or categories(may change measurement scale)
How is reclassification data done assuming you an environmental analyst studying elevation data of a mountainous region. You have a mountainous region where each cell represent elevation data. And you want to reclassify them into 3 classes (low elevation 0-500meters, medium elevation: 501 - 1500meter, and high elevation 1501 meters and above)
You ensure that all relevant data is located in the project.
Go to analysis tab , click on tools to open geoprocessing pane where you will search for and find reclassify tool.
Configure the reclassify tool :. Select relevant raster data large , choose the field that contains elevation data ( usually value). Define new classes according to needs . Specify what happens with cells that have no data .
Click run .
Overlay has todo with the Aor B , Aand B etc.
Check slides to revise
True or false: raster calculator performs overlay
True
Where can the raster calculator be found ?
In the geoprocessing pane where under the arc toll box drop down under map algebra
Over lay can also be done using logical toll box : found in the arctoolbox under the math drop down .
What is slope and how is it calculated?
Slope is the measure of how steep a terrain is .
How it is calculated: the elevation data of a single spell is compared to 8 of its neighbors , and the steepest angle from ascent or descent is calculated from the center cells to its neighboring cells . This angle is the slope
What is aspect ?
Aspect determines the compass direction that a slope faces
Euclidean , Manhattan and proximities examples check post it note .
Euclidean distance
This normally measured as a straight line accords the raster data set . This can be done using spatial analyst tools in he arc tool box.
How are buffers calculated in raster data set
- Calculate Euclidean distance
- Reclassify distances to represent buffer width.
