Geography
Week 1
.gdb is the esri file type. It is messy inside.
save as project.
.gdb only contains the data
project file will contain the changes we make (like the symbology) and what we actually do.
Two types of data:
coordinate - pairs or triplets of numbers defining location
atrribute - text, numbers, images (non-spatial data)
Spatial objects
points - 0 dimensions
lines - 1 dimensions
areas - 2 dimensions
surfaces
volumes
Raster and vector
- these are layer types
Object view:
discrete objects
- buildings, lakes, etc.
Field view:
continuously
- oceans, terrain
raster is a giant matrix basically.
- there are cells.
Bolstad et al:
Coordinate Systems:
- coordinates are used to define the spatial location and the extent of geographic objects.
Digital spatial data:
vector data model: this model uses discrete elements such as points, lines, polygons. to represent geometry of real-world entities.
- farm fields, roads, wetlands, cities, and census tracts are examples of entities that are often represented by discrete vector objects.
- poins, lines, polygons.
Raster data model:
grid ceells - think of a matrix.
generally used for continuous variables.
- elevation, temperature, slope, average rainfall.
can also be used for scirete features
- political units, vegetation.
They have cell dimensions
- smaller cells = more detail = more data space on your comp.
the line starting and eding points are often called nodes, and intermediate points used to represent the line shape are called vertices.
Week 2:
Understanding Cartographic Scale & Spatial Resolution
Map scale:
the ratio between map distance and real world distance
“Amount of reduction in the representation of a real world phenomenon on a map”
Geometric error greater for smaller area
1:250,000 is larger scale than 1:1,000,000
Large scale maps cover small area but more detail ( we assume constant paper size)
Resolution:
smallest spatial addressable unit in our representation
- smallest unit the map can present
Line length decreases with more generalization.
Week 3:
Datum = reference point.
Longitude was actually very hard to figure out.
Map projection: a means of fitting features from the 3-D globe to a 2-D medium (map, computer screen)
No proper way to represent everything - THERE WILL BE DISTORTIONS.
use UTM zones for specific state maps - this will minimize distortion.
False Nothing
False Easting: 500,000m west of the zone’s central meridian
US State Plane Coord system - better for study of states.
Citation
@online{neilon2025,
author = {Neilon, Stone},
title = {Geography},
date = {2025-01-14},
url = {https://stoneneilon.github.io/notes/American_Behavior/},
langid = {en}
}