Download presentation

Presentation is loading. Please wait.

Published byKai Barnes Modified over 2 years ago

1
Intro. To GIS Midterm Review March 8 th, 2013

2
Reminders Lab on next Monday Try to catch up on homework assignments

3
Why Georeferencing?

4
Georeferencing – The process of converting a map or an image (or scanned map) from one coordinate system to another by using a set of control points and a transformation equation. Two steps – Coordinate transformation (scaling, rotating, skew) – Resamping Georeferencing

5
Coordinate Transformation Methods – First-order polynomial (Affine) – 2 nd Order polynomial – 3 rd order polynomial – Spline 2 nd order 1 st order >>Control points are used to estimate the coefficients (a0,b0,…)<<

6
Transformation types: Affine The affine transformation function is: x’ = Ax + By + C y’ = Dx + Ey + F where x and y are coordinates of the input layer and x’ and y’ are the transformed coordinates. The C and F parameters control shift in origin (translation) A, B, D, E control scale and rotation their values are determined by comparing the location of source and destination control points. Scales, skews, rotates, and translates 6 unknowns( A,B,C,D,E,F) so a minimum of three “displacement links” required Little benefit from more than 18-30 links The most common choice

7
Example: Transformation Let’s do a simple example – We would like to calculate new coordinates for point A(x=1, y=1), i.e., we want to convert coordinate system (x,y) to (x’,y’). – We assume a 1 st order (affine) transformation works fine – All the six coefficients (for affine transformation) are given (a0=1, a1=1.1, a2=0.4 and b0=0.2,b1=1.8,b2=0.8) – x’ and y’ are the new coordinates for (x,y) in the new coordinate system – Continue on next Slide >>>>

8
Resampling coordinate 68 65 70 80 Pixel value x x’ 78 7378 74 69 y 1 1 2 3 2 3 1 2 3 1 2 3 y’ e.g., Average of 80 and 68 would be the pixel’s new value

9
A bit of clarification on Optical RS The end result is surface reflectance/temperature or a thematic map (classified map)

10
Orthophoto Vs. Aerial photos (or Remotely sensed Imagery)

12
Midterm Overview Based primarily on lecture and homework/book Good knowledge of lab exercises helps! Closed notes, closed book, no computers Basic calculators Question types will include: – Multiple choice – True-False – Short answer – Few long answer

13
Vector Data and Topology Topology – The arrangement for how point, line, and polygon features share geometry – Or knowledge about relative spatial positioning Two types of vector models exist in a GIS – Geo-relational Vector Model Arc Coverage (has topology) >>> format: binay Shape files (no topology) >>>> format: *.shp, *.shx, *dbf, etc. – Object-based Vector Model Includes classes and geodatabases >>> format: *.mdb

14
Topology Concepts – Adjacency – Enclosure – Connectivity Terms to be defined – Node – Arc – Polygon

15
Query A query is a “question” posed to a database (attribute data) Examples: – Mouse click on a map symbol (e.g. road) may mean What is the name of road pointed to by mouse cursor ? – Typing a keyword in a search engine (e.g. google, yahoo) means Which documents on web contain given keywords? – SELECT ‘FROM Senator S’ WHERE S.gender = ‘F’ means Which senators are female?

16
Organizing Attribute Data Flat Files – Spreadsheets (e.g. excel spreadsheet)

17
Hierarchical Organizing Attribute Data

18
Relational ( What is commonly used in GIS ) – Various tables (databases) are “linked” through unique identifiers Organizing Attribute Data

19
Query: Making Selections Usually interested in some subset of the data Selections can be made in two primary ways: – Select by Attribute – specify matching criteria – Select by Location – based on spatial proximity

20
Select by Attribute Tips Be careful with case sensitivity and spaces Use parentheses to carefully construct a query Use “Boolean” Operators (AND, OR, NOT, LIKE) – AND means both criteria, OR means either – NOT allows you to exclude some criteria – LIKE lets you be more flexible, use wildcard characters (_ for one character, % for many) – Verify your expression to make sure it works

21
Selection Criteria (#8.8) CountryPopulation (millions) Energy Use (barrels of oil per capita) Infant Mortality (per 1000) Life Expectancy (per 1000) Car Theft (%) Australia19.95,668479.22.2 England59.35,945577.52.6 Finland5.26,456478.00.5 France59.74,350479.21.8 Japan127.24,071381.60.1 Netherlands16.25,993578.30.5 Norway4.66,019478.91.5 South Africa45.33,7035246.52.4 Spain41.12,945578.30.5 United States291.08,066777.30.5 Per capita energy use > 4,000 AND population < 20,000,000

22
Selection Criteria (#8.8) CountryPopulation (millions) Energy Use (barrels of oil per capita) Infant Mortality (per 1000) Life Expectancy (per 1000) Car Theft (%) Australia19.95,668479.22.2 England59.35,945577.52.6 Finland5.26,456478.00.5 France59.74,350479.21.8 Japan127.24,071381.60.1 Netherlands16.25,993578.30.5 Norway4.66,019478.91.5 South Africa45.33,7035246.52.4 Spain41.12,945578.30.5 United States291.08,066777.30.5 [Per capita energy use 40,000,000)] AND (car theft <1)

23
Selection Criteria (#8.8) CountryPopulation (millions) Energy Use (barrels of oil per capita) Infant Mortality (per 1000) Life Expectancy (per 1000) Car Theft (%) Australia19.95,668479.22.2 England59.35,945577.52.6 Finland5.26,456478.00.5 France59.74,350479.21.8 Japan127.24,071381.60.1 Netherlands16.25,993578.30.5 Norway4.66,019478.91.5 South Africa45.33,7035246.52.4 Spain41.12,945578.30.5 United States291.08,066777.30.5 Population 1.5

24
GOOD LUCK ON YOUR MIDTERM!

Similar presentations

OK

Intro to GIS & Pictometry Trainers: Randy Jones, GIS Technician, Douglas County Jon Fiskness, GISP GIS Coordinator, City of Superior.

Intro to GIS & Pictometry Trainers: Randy Jones, GIS Technician, Douglas County Jon Fiskness, GISP GIS Coordinator, City of Superior.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on complex numbers class 11th sample Ppt on new zealand culture and customs Download ppt on tsunami Ppt on atm machine working Ppt on obesity diet and exercise Ppt on bluetooth broadcasting system Ppt on data collection methods aba Ppt on 21st century skills education Ppt on turbo generators manufacturers Ppt on network switches