GIS Section 4 Flashcards
What is spatial modelling?
-process of building algebraic expressions that represent models through equations
What are the variables of a spatial model?
thematic layers in the GIS database
What tool is used to build spatial models
Raster Calculator (in ArcGIS)
What is necessary for fitting a regression model?
statistics
What is geoprocessing?
- a framework and set of tools for processing geographic and related data in an automated way
- proprietary term of esri
What does geoprocessing do?
- performs an operation on a dataset (including vector, raster, tables)
- creates resulting output dataset
What analytical operations are a part of geoprocessing?
- Map Algebra
- Spatial Modelling
What kinds of information are included in a flowchart of a GIS process?
- type of analytical operation
- data type
- result of each operational step
What ArcgGIS tool is used for building functional flowcharts?
Model Builder
What starting information might be useful for suitability models?
- both raster and vector data
- land cover
- soil types
- slope
- distance from streams
- distance from roads
What 3 main sets of operations are used in Vector spatial analysis?
- Extract
- OVerlay Analysis
- Proximity Analysis
What types of overlay types can you use on vector objects?
- union
extract (special) - intersect
erase - identity
- update
What does the intersect feature do in a vector overaly?
builds a new feature class from the intersecting features in common with both input feature classes
What does the Union function do in vector data?
- combines features and attributes of the input feature classes
- geometric intersection
What does the Clipping operation do in vector data?
uses the boundaries of one feature class to define the boundaries of the other input feature class
- ‘cookie cutter’
When is clipping particularly useful?
when creating a new layer that contains a geographic subset of another layers features
What does dissolving features do in vector data?
simplifies the data based on common attributes - merges similar features together
What is the output of dissolving vector data?
- fewer output features with attribute values
What is involved in a proximity analysis?
- Distance operators
- Context operators
- Connectivity operators
How are buffers created?
- buffer routine:
- traverses each of the input feature’s vertices and creates buffer offsets
What are some other proximity analysis operations?
- distance
- point distance
- near distance
What is a variable buffer?
buffer with different buffering distances for each line segment
What are ring buffers?
buffers around point features
