# Lecture 3: Vector Analysis

## What are the basic geometric vector operations?

computation of distance b/w 2 features, calculating the length of line objects, calculating polygon areas, calculating line intersects

## Name the four computation of distance

Euclidian distance, distance in a network, topographical distance, spherical distance

## What does it mean if the # of intersections is odd in point-in-polygon?

the point is in the polygon

## What is the result of a buffer zone?

Polygon layer

## Which three vector overlays are there?

points in polygon, lines in polygon, polygons in polygons

## Points on Polygons:

Decide which points lie in which polygons, transfer attributes from the polygons to those points that fall within them (one to many) and the result is a point LAYER with their original + polygon attributes

## What is not automatically updated in shape file format?

length and area attributes

## Common problem with polygon on polygons?

Slivers

## What are the post overlay clean-up operations?

clip, dissolve, merge, eliminate

## Explain clip

Same principle as polygon on polygon only no attributes from clip layer included in result table

## Explain dissolve

It makes new bigger polygons based on attribute values

## Eliminate

Used to remove slivers based on a certain threshold value

## Merge

bringing together two data layers in order to make a larger database

## What influences vector analysis?

map projection, generalisation, precision