GIS Analysis Functions

Objectives• To be able to explain what the following

GIS analysis functions are:– Transformations– Conflation– Edge Matching– Editing Functions– Query Functions– Overlay Operations– Neighborhood Operations– Connectivity Functions

Transformations• Format Transformations

- sometimes topology must be built

• Geometric Transformations - registration to a common coordinate system (rubber sheeting or warping)

• Between Geometric Projects - i.e. Latitude/Longitude to PLSS

Conflation • procedure of reconciling the positions of

corresponding features in different layers (i.e. if two forests layers are off - conflation fixes)

Edge Matching• adjusts the position features that extend

across map boundaries ("postage-stamping" maps together and resolving the differences in features along their edges...)

Editing Functions• slivers or splinters

• line snapping

• over- or undershoots 

Query Functions

• retrieve records in the attribute database according to the conditions specified by the operator

Overlay Operations• arithmetic & logical

overlay operations

• arithmetic - addition, subtraction, division, multiplication

• logical - where a specified set of conditions occur (or doesn't occur) together

Neighborhood Operations• evaluate the characteristics of the area

surrounding a specified location

Other Analyses

Connectivity Functions

• use functions that accumulate values over the area being traversed

Conclusion

• GIS analysis functions use the spatial and non-spatial attribute data to answer questions about real-world

• Spatial analysis functions that distinguishes GIS from other information systems