GIS data analysis

GIS DATAANALYSIS
 Raster to Vector Conversion
 Spatial analysis through vector overlay
Dr. Arindam Sarkar , Department of Geography
Purash Kanpur Haridas Nandi College Website: https://pkhnm.ac.in/
Email ID: arindam.srkr1@gmail.com
Dr. Arindam Sarkar
Department of Geography
Purash Kanpur Haridas Nandi College
PO: Kanpur, District: Howrah

GIS data type
Spatial data: It is related to geometry of spatial feature
Attribute data: It is associated with information about the spatial feature
Spatial data:
• It represent spatial feature of the Earth’s surface on map (plane surface)
• Location of each feature is determined by Cartesian coordinate system (x,y axis, geographic grid:
latitude and longitude)
• Types of Spatial data: Discreet feature data and Continuous feature data.
• Discreet feature are those that do not exists between observations, form separate entities and are
individually distinguishable (Dent,1999)
• Example of discreet feature data: Ponds, wells, road, agricultural land etc.
• Continuous feature exists spatially between observations (Dent,1999)
• Example of Continuous feature data: Precipitation , elevation, soil pH etc.
GIS data model
• Raster data model
• Vector data model

Spatial data
Raster data Vector data
Topological Non topological
High-level data Simple data
TIN Regions Dynamic segmentation

Raster Vector
Raster data use a matrix of square areas to
define where feature are located.
These square is also called pixels, cells and
grids, typically are of uniform in size.
Raster data is used for capturing, storing and
analyzing data such as elevation, temperature,
soil organic matter etc.
Raster data format are also used to store
aerial photograph and satellite imagery.
Raster is made up of pixel (or cells). Each
pixel has an associated value (DN value).
Digital image is an example of raster data set.
Each pixel value correspondence with a
particular colour.
 Vector data uses X.Y coordinate to define the
location of a points, lines and polygons , that's
corresponds to map feature.
 Vector data are excellent for capturing and
storing spatial details.
Vector data consists of individual points,
which (2D format data) are stored as pairs of
(X,Y) CO-Ordinates.
The point may be joined in a particular order
to create line or joined into closer rings to create
polygons.

GIS data analysis
Raster data analysis Vector data analysis
Map manipulationBuffering
• Point buffer
• Line buffer
• Area buffer
(Polygon
buffer
Vector data overlay
• Point-in-polygon
• Line-in-polygon
• Polygon-on-polygon
Distance
measurement
Reclassification
Raster data overlay
• Point-in-polygon
• Line-in-polygon
• Polygon-on-polygon
Terrain mapping
• BPD or DEM
• Contour map
• Hill shade map
Terrain analysis
• Slope map
• Aspect map
Spatial interpolation
Global method
• Trend Surface Analysis
• Regression models
Local method
• Thiessen Polygons
• Density Estimation
• Inverse Distance
Weighted (IDW)
• Thin –plate Splines
• Kriging

Raster data overlay
 Point-in-polygon
 Line-in-polygon
 Polygon-on-
polygon

Vector Map overlay
• Point-in-
polygon
• Line-in-
polygon
• Polygon-on-
polygon
• Point-in-
polygon.
• Line-in-
polygon

Map Overlay method
1.Clipping
2.Erase or delete
3.Split
4.Identity
5.Union
6.Intersect

Spatial data editing
Digitization – error due to digitization
Types of error occur
due to digitization
• Location error
• Topological error
(over shoot , under
shoot)
Topological and non-topological editing
Edge matching
Non-topological editing
• Delete
• Move
• Cut
• Paste
• Reshape
• Split
• Merge
Manipulation feature
• Line simplification
• Densification
• SmoothingDr. Arindam Sarkar , Department of Geography

GIS data analysis

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