class: center, middle, inverse, title-slide # Geomática Basica ## Lecture 2 ### Ivan Lizarazo ### 09.03.2022 --- class: inverse, middle, center background-image: url(http://www.ga.gov.au/__data/assets/image/0020/61328/LakeEyreFilling_banner.png) background-size: 500px background-position: 50% 80% # Let's continue --- # Agenda ### 1. What is GIS? What are the GIS components? ### 2. From real-world to geodata ### 3. Geospatial data models and structures ### 4. Coordinate Systems ### 5. GIS software --- class: inverse, middle, center # What is GIS? What are the GIS components? --- background-image: url(images/quilla.png) background-size: 450px background-position: 50% 90% ### A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. ### The key word to this technology is Geography: - this means that some portion of the data is (geo)spatial. - data that is referenced to locations on the earth. --- background-image: url(images/chang1.png) background-size: 450px background-position: 50% 90% ### Coupled with the geospatial data is usually tabular data known as attribute data: - Attribute data can be generally defined as additional information about each of the spatial features. - An example of this would be *street networks*. The actual location of the roads is the spatial data. - Additional data such as name, speed limit, direction, would make up the attribute data. #### These two data types enable GIS to conduct spatial analysis. --- background-image: url(images/gis_components.png) background-size: 400px background-position: 50% 90% ### Components of a GIS: - Geodata (files, spatial database) - Hardware - Software - People - Organization (teams, standards, protocols,..) --- class: inverse, middle, center # From real-world to geodata --- background-image: url(images/curves.png) background-size: 450px background-position: 50% 90% # Dimensions of space, time and scale - **Space** is the boundless 3D extent in which objects and events occur and have relate position and direction - **Time** is a dimension used to sequence events, to compare the duration of events and the intervals between them, and to quantify rates of changes - **Scale**: (i) scope or extent: (ii) measurement system; (iii) map scale --- background-image: url(images/decision-making.png) background-size: 300px background-position: 50% 90% # Hierarchy of decision making .pull-left[ ### Level of decision - Wisdom - Knowledge - Evidence - Information - Data ] .pull-right[ ### Easy of sharing - Impossible - Difficult - Hard to say - Fair - Easy ] --- background-image: url(images/opendata.png) background-size: 550px background-position: 50% 90% # Geospatial data - Data is any set of raw facts that have been collected and from which inferences may be drawn - Information is __any useful data__ that satisfies some user needs. - Geodata is __any geographically referenced data__ - Geodata **quality** matters --- class: inverse, middle, center # Geospatial data models and structures --- background-image: url(images/from_world.png) background-size: 250px background-position: 50% 90% # Geospatial Data Modeling #### Putting a __representation__ of the real world into a computer - To serve a certain __goal__ - Valid within a certain __context__ according to certain __perception__ of the world - Expressed using some kind of __schema__ or __logic__ - Implemented in a database using some language --- background-image: url(images/sandwich.png) background-size: 350px background-position: 40% 90% # Spatial perception ### Goal and context - Definition: What are the objects considered - Level of detail: What do I consider an object - Scales: To what detail do I need to consider these objects ### Discrete view and continuous view - one **omnipresent** phenomena - several **neighbouring** phenomena --- background-image: url(images/fields_objects.png) background-size: 400px background-position: 40% 90% # Spatial representation ### Continuous view -> Fields - Location determines value ### Discrete view -> Objects - Boundary determines value --- class: inverse, middle, center # Coordinate reference systems (CRS) --- background-image: url(images/geographic_CRS.png) background-size: 500px background-position: 40% 70% ### Geographic coordinates systems are 3D references systems --- background-image: url(images/LONG_LAT.png) background-size: 700px background-position: 40% 80% ### Geographic coordinates as expressed as **angles** #### a = Longitude (top view) #### b = Latitude (side view) --- background-image: url(images/map_projection.png) background-size: 700px background-position: 40% 80% ### Map projections on globes - They are used to flatten the sphere out in two-dimensions. - But ... you can’t represent Earth’s surface in two dimensions without distortion. --- background-image: url(images/UTM_1.png) background-size: 500px background-position: 50% 80% #### [Universal Transverse Mercator](https://gisgeography.com/utm-universal-transverse-mercator-projection/) Projection - A UTM zone is a 6° segment of the Earth. - There are 60 UTM zones on Earth. - ... --- background-image: url(images/UTM_2.png) background-size: 500px background-position: 50% 80% #### The Transverse Mercator takes a cylinder and rotates it 90° - ... --- background-image: url(images/UTM_3.png) background-size: 500px background-position: 50% 80% #### UTM applies a secant cylinder which intersects the ellipsoid #### along two small circles parallel to the central Meridian - ... --- background-image: url(images/UTM_4.png) background-size: 800px background-position: 50% 80% #### Instead of using latitude and longitude coordinates, #### each 6° wide UTM zone has a central meridian of 500,000 meters. --- class: inverse, middle, center # GIS software --- background-image: url(images/FOSS.png) background-size: 600px background-position: 50% 90% ### Two choices: - Propietary software: - ArcGIS (ESRI) - Free open source software (FOSS): - R, QGIS, SAGA GIS, GRASS GIS --- class: middle, center background-image: url(http://www.ga.gov.au/__data/assets/image/0020/61328/LakeEyreFilling_banner.png) background-size: 500px background-position: 50% 80% # Thanks!