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Lecture

ESSE 3600 Lecture Notes - Data Type, Spatial Analysis, Measurement Uncertainty

by

Department
Earth, Space Science and Engineering
Course Code
ESSE 3600
Professor
Sohn

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of 2
Creating a Vector GIS Database
Refer to diagram
Spatial Models
A spatial model is a conceptualization. Perception is subjective, and conceptual models are
formalized models to represent the real world. Ie physical description, spatial description
How can we digitize and convert what we have?
How can the flat Google Images map be conceptualized to show 3D?
ie fire at Petrie Science Building
From the real world to the physical model, we have ONE DATA SHAPEFILE.
If we look at the vertical axis and degree of simplifications, it is high at the bottom level on the
flowchart.
Geographical data is never organized.
Note that object-based models deal with descriptive data, and field based models deal with
points and arbitrary locations.
The inexact boundary has to be generated to become a more exact boundary.
Field based raster, object based raster.
Measurement uncertainty needs to be modelled in data. The road can be digitized, and satellite
images can be used to get a general shape of the boundary object data.
Field based view is good for weather predictions and simulations. The use of variables in space
requires the use of large pixels.
Field space is grid. The resolution depends on the original accuracy.
The problem with objects is that it is too approximate and it is not always accurate. Points, lines
and polygons can be defined in different dimensions.
Object data is often found on aerial images. An attribute of an bject would be the postal code,
for example. Is it a road or a highway? Etc.
Slide 26-ex: Ab, bc, cd…This is necessary to specify where coordinates are for the comp
A field point sample gets converted into a polygon.
Spatial model is a generalization of reality, simplification.
Object based or field based?
Data type is either vector or raster.
orientation: angle bw geodetic north and the local coordinate