A map projection is a method for mapping spatial patterns on a curved surface (the Earth's surface) to a flat surface. Projections always introduce some distortion of properties like shape, area, direction, or distance. Common projections include Albers, Lambert Azimuthal Equal Area, Mercator, Miller, Mollweide, and Orthographic. Coordinate systems like State Plane and UTM provide a measurement framework by assigning coordinates using projections. Datums define a reference system to place coordinate systems on the Earth's surface and commonly used datums include NAD27, NAD83, and WGS84. Projecting spatial datasets allows data from different sources and projections to be made compatible for analysis.
This document discusses different types of map projections used to represent the spherical earth on a flat surface. It describes how all projections involve some distortion of properties like shapes, areas, distances or directions. The key types are conformal, equivalent, and equidistant projections. It explains the concepts of projection surfaces like cones, cylinders and planes, as well as variables like the light source and orientation. Specific common projections are also outlined, such as Mercator, Lambert conformal conic, and azimuthal equidistant, along with their characteristic distortions and uses.
Combined gis 2(GEOGRAPHIC INFORMATION SYSTEM)musadoto
Distortions
• The earth is spherical, and a simple way of mapping it without distortion is to map it on a globe. However, mapping on globes is not possible.
• The transformation from the three-dimensional ellipsoid/sphere to the two-dimensional plane (flat) surface is not possible without some form of distortion.
• The distortions increase as the distance from the central point of the projection increases
• Areas smaller than 25 x 25 km:
No distortions
• Areas larger than 25 x 25 km:
Always distortions
• Map projections are used to control/minimize the distortions
Classification and properties of map projections
Properties of map projections
• Areas are everywhere correctly represented
• All distances are correctly represented
• All directions on the map are the same as on Earth
• All angles are correctly represented
• The shape of any area is correctly represented (e.g. a circle projected would remain a circle)
The document discusses different types of map projections used to represent the spherical Earth on a flat surface. It begins by explaining that map projections transform 3D global coordinates to 2D planar coordinates, which necessarily distorts properties like distances, angles, or areas. It then covers key projection categories (cylindrical, conic, azimuthal), their characteristic properties and examples. Specific projections discussed include Mercator, UTM, and polar stereographic. The document emphasizes that the appropriate projection depends on the map's intended use and which distortions are least important. It encourages map users to understand basic projection concepts.
This document provides information on map projections. It defines map projection as a systematic transformation of locations on Earth onto a plane. It discusses the three main types of projections: planar, cylindrical, and conic. Planar projections center on a point and are accurate near the center, cylindrical projections are rolled onto a cylinder and accurate along the equator, and conic projections use a cone and are suited to limited east-west areas near the equator. It also discusses properties like shape, area, direction, and distance distortions that occur in projections and notes no projection is perfect. Common projections like Mercator, UTM, and Robinson are described.
coordinate systems map Projections and Atoms ppt - - Copy.pptxBakhtAli10
This document discusses coordinate systems, geodetic datums, and map projections. It defines coordinate systems as reference systems that locate geographic features within a common framework. The two main types are geographic coordinate systems (GCS) that use latitude and longitude, and projected coordinate systems (PCS) that convert GCS to planar coordinates for mapping. Geodetic datums define the position and orientation of reference spheroids used in GCS. Common datums include NAD27 and NAD83. Map projections convert the spherical Earth to flat maps, necessarily introducing distortions of shapes, distances, areas, or directions depending on the specific projection used.
Remote sensing and GIS techniques are useful tools for civil engineering projects. There are several models that can be used to represent the shape of the Earth, including flat, spherical, and ellipsoidal models. The ellipsoidal model is needed for accurate measurements over long distances. A geodetic datum defines the parameters of the reference ellipsoid and the orientation of the coordinate system grid. Common datums include NAD27 and NAD83, and transformations allow conversion between them. Map projections, such as Mercator and UTM, are used to represent the 3D Earth on a 2D surface, inevitably distorting some spatial properties like shape, area, or distance.
Spheroid, datum, projection, and coordinate systems are used to locate positions on Earth. A spheroid is a mathematical model that approximates the Earth's shape as an oblate spheroid. A datum defines the reference frame for latitude and longitude coordinates and relates the spheroid to the Earth's center. Projections transform 3D spheroid coordinates onto a 2D surface like a map, introducing some distortion of shapes, areas, distances or directions. Common projections include transverse Mercator, UTM, and lambert conformal conic. Coordinate systems then allow measurement of positions on the projected 2D surface. Understanding these concepts is important for accurately locating geographic features.
This document discusses different types of map projections used to represent the spherical earth on a flat surface. It describes how all projections involve some distortion of properties like shapes, areas, distances or directions. The key types are conformal, equivalent, and equidistant projections. It explains the concepts of projection surfaces like cones, cylinders and planes, as well as variables like the light source and orientation. Specific common projections are also outlined, such as Mercator, Lambert conformal conic, and azimuthal equidistant, along with their characteristic distortions and uses.
Combined gis 2(GEOGRAPHIC INFORMATION SYSTEM)musadoto
Distortions
• The earth is spherical, and a simple way of mapping it without distortion is to map it on a globe. However, mapping on globes is not possible.
• The transformation from the three-dimensional ellipsoid/sphere to the two-dimensional plane (flat) surface is not possible without some form of distortion.
• The distortions increase as the distance from the central point of the projection increases
• Areas smaller than 25 x 25 km:
No distortions
• Areas larger than 25 x 25 km:
Always distortions
• Map projections are used to control/minimize the distortions
Classification and properties of map projections
Properties of map projections
• Areas are everywhere correctly represented
• All distances are correctly represented
• All directions on the map are the same as on Earth
• All angles are correctly represented
• The shape of any area is correctly represented (e.g. a circle projected would remain a circle)
The document discusses different types of map projections used to represent the spherical Earth on a flat surface. It begins by explaining that map projections transform 3D global coordinates to 2D planar coordinates, which necessarily distorts properties like distances, angles, or areas. It then covers key projection categories (cylindrical, conic, azimuthal), their characteristic properties and examples. Specific projections discussed include Mercator, UTM, and polar stereographic. The document emphasizes that the appropriate projection depends on the map's intended use and which distortions are least important. It encourages map users to understand basic projection concepts.
This document provides information on map projections. It defines map projection as a systematic transformation of locations on Earth onto a plane. It discusses the three main types of projections: planar, cylindrical, and conic. Planar projections center on a point and are accurate near the center, cylindrical projections are rolled onto a cylinder and accurate along the equator, and conic projections use a cone and are suited to limited east-west areas near the equator. It also discusses properties like shape, area, direction, and distance distortions that occur in projections and notes no projection is perfect. Common projections like Mercator, UTM, and Robinson are described.
coordinate systems map Projections and Atoms ppt - - Copy.pptxBakhtAli10
This document discusses coordinate systems, geodetic datums, and map projections. It defines coordinate systems as reference systems that locate geographic features within a common framework. The two main types are geographic coordinate systems (GCS) that use latitude and longitude, and projected coordinate systems (PCS) that convert GCS to planar coordinates for mapping. Geodetic datums define the position and orientation of reference spheroids used in GCS. Common datums include NAD27 and NAD83. Map projections convert the spherical Earth to flat maps, necessarily introducing distortions of shapes, distances, areas, or directions depending on the specific projection used.
Remote sensing and GIS techniques are useful tools for civil engineering projects. There are several models that can be used to represent the shape of the Earth, including flat, spherical, and ellipsoidal models. The ellipsoidal model is needed for accurate measurements over long distances. A geodetic datum defines the parameters of the reference ellipsoid and the orientation of the coordinate system grid. Common datums include NAD27 and NAD83, and transformations allow conversion between them. Map projections, such as Mercator and UTM, are used to represent the 3D Earth on a 2D surface, inevitably distorting some spatial properties like shape, area, or distance.
Spheroid, datum, projection, and coordinate systems are used to locate positions on Earth. A spheroid is a mathematical model that approximates the Earth's shape as an oblate spheroid. A datum defines the reference frame for latitude and longitude coordinates and relates the spheroid to the Earth's center. Projections transform 3D spheroid coordinates onto a 2D surface like a map, introducing some distortion of shapes, areas, distances or directions. Common projections include transverse Mercator, UTM, and lambert conformal conic. Coordinate systems then allow measurement of positions on the projected 2D surface. Understanding these concepts is important for accurately locating geographic features.
Different types of Important projection systems & Coordinate systems.Every country would like to represent it's self in true shape, if shape changes then size , area also changes so that leads to distortions on the global properties of a map like Distance,direction,shape ,Area. so no country or continent will never like to represent themselves distorted , so hundreds of projections were developed by counties across the world.
This document discusses key concepts related to map projections and datums. It defines projections as mathematical transformations that take 3D objects on the earth's surface and project them onto a 2D surface, like a map, with minimal distortion. It discusses different types of projections, important properties to preserve like distances and shapes, and how different projections preserve certain properties better in specific regions. The document also defines datums as reference frames that define latitude/longitude and how local datums need to be transformed to global datums like WGS84. It explains factors like the earth not being a perfect sphere and irregular terrain that necessitate datums and datum transformations.
A graticule is a network of lines, sometimes described as a grid, that is used for geographic plotting, scale, and focusing depending on the application. A common example is a grid of lines on a map corresponding to longitude and latitude.
The first presentation for the mapping your data workshop. Much more informative, but not nearly as hands on. From an informational standpoint its better then 2, but from a workshop stand point it\'s much worse.
Cartography is the science of map making related to geography, mathematics, geodesy, and human habitat, economy and society. Its a discipline developed during the early period of human civilization. With the development of science and technology, it has changed its paradigm twice. Its been digital, more integrated and very useful global media for communication.
Map projections convert latitude and longitude coordinates on a spherical Earth into two-dimensional planar coordinates by applying a mathematical transformation. They define a coordinate system and allow measurement of horizontal and vertical distances to establish positions of geographic features. Creating a projection involves selecting an Earth model (sphere or ellipsoid) and transforming geographic to planar coordinates. Common projections preserve either shapes, areas, distances or directions depending on the mapping needs.
The document describes various types of map projections, including their standard presentations and key properties. It provides examples of specific projections like Mercator, UTM, and Mollweide and notes their creators and intended uses. Tables give more details on individual projections like their image type, properties preserved, year created, and brief descriptions.
This document discusses map projections, which are methods for translating the three-dimensional surface of the Earth onto a two-dimensional map. It describes three types of developable projection surfaces - conic, cylindrical, and planar - that are used to create different map projections. Specific projections are then outlined, including what geometric properties they preserve or distort (shape, area, distance, direction) and their common uses. The document provides a detailed overview of different GIS map projection techniques.
This document discusses map projections and their properties. Map projections transform the three-dimensional globe onto a two-dimensional surface, necessarily introducing some distortions. The best projection depends on the map's purpose and region. Common projections include cylindrical (like Mercator), conic, and planar/polar types. Key properties that projections aim to preserve, like shape, area, distance and direction, often involve tradeoffs. Choosing a projection minimizes distortions for a map's intended use and geographic extent.
This document provides information about Earth's spheres and mapping locations on Earth. It discusses the geosphere, atmosphere, hydrosphere, and biosphere. It describes latitude and longitude and how they are used in a coordinate system to locate positions on Earth. It also covers topics like time zones, topographic maps, and drawing contour lines.
This Presentation is to made concepts about measuring the earth (to locate position of any person on the whole earth). For this purpose we re going step by step basis in this presentation.These steps are mentioned as contents. After that you may able to learn about measuring a person's position of earth. Thank you!
Map projections allow geographic information on the spherical Earth to be represented on a flat surface like a map. There are many types of map projections that preserve different spatial properties through various techniques. The key types are cylindrical, conic, and planar/azimuthal projections which result from projecting graticules from a globe onto developable surfaces like cylinders, cones, or planes. Properties like area, shape, direction, and distance are differently preserved depending on the specific projection used.
Map projections allow the representation of locations on the spherical Earth on a flat surface by transforming geospatial coordinates using mathematical formulas. There are different types of map projections that preserve various geometric properties to differing degrees, such as distance, shape, or direction. It is important to choose a projection and coordinate system that suit the intended mapping purpose. Coordinate systems use datums to define relationships between coordinates and locations on the Earth's irregular surface.
Projecting maps involves converting the spherical earth into a flat plane, which inevitably causes some distortion of properties like angles, areas, directions, and shapes. There are three main types of map projections - cylindrical, conical, and planar - which involve wrapping a lighted globe onto different geometric surfaces like a cylinder, cone, or flat plane. The Mercator projection specifically was created to aid navigation by representing lines of constant bearing as straight lines, though it distorts the relative sizes of land areas farther from the equator. The Universal Transverse Mercator (UTM) system divides the earth into zones and uses the Mercator projection locally in each to assign Cartesian coordinates.
This document provides an overview of different methods of georeferencing, or assigning locations to information on maps. It discusses various systems like placenames, addresses, postcodes, cadastral maps, and coordinate systems. Latitude and longitude provide a comprehensive global standard, but distortions require map projections like UTM for GIS. GPS allows direct measurement of coordinates with increasing accuracy from basic to differential systems. Georeferences must be unique, shared, and persistent over time to be useful references in maps and spatial analysis.
This document discusses different map projections and their uses. It begins with an introduction to projections and why they are needed to represent the spherical Earth on a flat surface. It then covers key terminology, different types of projections including cylindrical, conical and azimuthal, and which projection types are best suited for different regions and purposes based on whether they preserve properties like shape, area, or distance. The document provides examples of commonly used projections for specific regions and concludes with references.
Coordinate system Geographical coordinate systemNaresh Kumar
UTm Universe transvers mercator, Geographic coordinate system
geoid, planar projection, cylindrical and conical projection, longitudinal, latitude, UTM zones 60 zones
The document provides an overview of map projections, which are mathematical transformations that convert the spherical coordinates on the Earth's surface to planar coordinates that can be represented on a map. It discusses the different types of projections, including cylindrical, conical, and planar projections. It also covers important concepts like datums, ellipsoids, and how different projections preserve properties like shapes, distances, areas, or directions to varying degrees based on their mathematical properties and construction.
This document provides information about basic concepts related to charts used for aviation purposes. It discusses key terms like maps, charts, projections and distortions that occur when representing the spherical Earth on a flat surface. It also describes different types of projections including plane, conical, cylindrical and their characteristics. Specific projections like Mercator and Lambert Conformal are explained in more detail.
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Different types of Important projection systems & Coordinate systems.Every country would like to represent it's self in true shape, if shape changes then size , area also changes so that leads to distortions on the global properties of a map like Distance,direction,shape ,Area. so no country or continent will never like to represent themselves distorted , so hundreds of projections were developed by counties across the world.
This document discusses key concepts related to map projections and datums. It defines projections as mathematical transformations that take 3D objects on the earth's surface and project them onto a 2D surface, like a map, with minimal distortion. It discusses different types of projections, important properties to preserve like distances and shapes, and how different projections preserve certain properties better in specific regions. The document also defines datums as reference frames that define latitude/longitude and how local datums need to be transformed to global datums like WGS84. It explains factors like the earth not being a perfect sphere and irregular terrain that necessitate datums and datum transformations.
A graticule is a network of lines, sometimes described as a grid, that is used for geographic plotting, scale, and focusing depending on the application. A common example is a grid of lines on a map corresponding to longitude and latitude.
The first presentation for the mapping your data workshop. Much more informative, but not nearly as hands on. From an informational standpoint its better then 2, but from a workshop stand point it\'s much worse.
Cartography is the science of map making related to geography, mathematics, geodesy, and human habitat, economy and society. Its a discipline developed during the early period of human civilization. With the development of science and technology, it has changed its paradigm twice. Its been digital, more integrated and very useful global media for communication.
Map projections convert latitude and longitude coordinates on a spherical Earth into two-dimensional planar coordinates by applying a mathematical transformation. They define a coordinate system and allow measurement of horizontal and vertical distances to establish positions of geographic features. Creating a projection involves selecting an Earth model (sphere or ellipsoid) and transforming geographic to planar coordinates. Common projections preserve either shapes, areas, distances or directions depending on the mapping needs.
The document describes various types of map projections, including their standard presentations and key properties. It provides examples of specific projections like Mercator, UTM, and Mollweide and notes their creators and intended uses. Tables give more details on individual projections like their image type, properties preserved, year created, and brief descriptions.
This document discusses map projections, which are methods for translating the three-dimensional surface of the Earth onto a two-dimensional map. It describes three types of developable projection surfaces - conic, cylindrical, and planar - that are used to create different map projections. Specific projections are then outlined, including what geometric properties they preserve or distort (shape, area, distance, direction) and their common uses. The document provides a detailed overview of different GIS map projection techniques.
This document discusses map projections and their properties. Map projections transform the three-dimensional globe onto a two-dimensional surface, necessarily introducing some distortions. The best projection depends on the map's purpose and region. Common projections include cylindrical (like Mercator), conic, and planar/polar types. Key properties that projections aim to preserve, like shape, area, distance and direction, often involve tradeoffs. Choosing a projection minimizes distortions for a map's intended use and geographic extent.
This document provides information about Earth's spheres and mapping locations on Earth. It discusses the geosphere, atmosphere, hydrosphere, and biosphere. It describes latitude and longitude and how they are used in a coordinate system to locate positions on Earth. It also covers topics like time zones, topographic maps, and drawing contour lines.
This Presentation is to made concepts about measuring the earth (to locate position of any person on the whole earth). For this purpose we re going step by step basis in this presentation.These steps are mentioned as contents. After that you may able to learn about measuring a person's position of earth. Thank you!
Map projections allow geographic information on the spherical Earth to be represented on a flat surface like a map. There are many types of map projections that preserve different spatial properties through various techniques. The key types are cylindrical, conic, and planar/azimuthal projections which result from projecting graticules from a globe onto developable surfaces like cylinders, cones, or planes. Properties like area, shape, direction, and distance are differently preserved depending on the specific projection used.
Map projections allow the representation of locations on the spherical Earth on a flat surface by transforming geospatial coordinates using mathematical formulas. There are different types of map projections that preserve various geometric properties to differing degrees, such as distance, shape, or direction. It is important to choose a projection and coordinate system that suit the intended mapping purpose. Coordinate systems use datums to define relationships between coordinates and locations on the Earth's irregular surface.
Projecting maps involves converting the spherical earth into a flat plane, which inevitably causes some distortion of properties like angles, areas, directions, and shapes. There are three main types of map projections - cylindrical, conical, and planar - which involve wrapping a lighted globe onto different geometric surfaces like a cylinder, cone, or flat plane. The Mercator projection specifically was created to aid navigation by representing lines of constant bearing as straight lines, though it distorts the relative sizes of land areas farther from the equator. The Universal Transverse Mercator (UTM) system divides the earth into zones and uses the Mercator projection locally in each to assign Cartesian coordinates.
This document provides an overview of different methods of georeferencing, or assigning locations to information on maps. It discusses various systems like placenames, addresses, postcodes, cadastral maps, and coordinate systems. Latitude and longitude provide a comprehensive global standard, but distortions require map projections like UTM for GIS. GPS allows direct measurement of coordinates with increasing accuracy from basic to differential systems. Georeferences must be unique, shared, and persistent over time to be useful references in maps and spatial analysis.
This document discusses different map projections and their uses. It begins with an introduction to projections and why they are needed to represent the spherical Earth on a flat surface. It then covers key terminology, different types of projections including cylindrical, conical and azimuthal, and which projection types are best suited for different regions and purposes based on whether they preserve properties like shape, area, or distance. The document provides examples of commonly used projections for specific regions and concludes with references.
Coordinate system Geographical coordinate systemNaresh Kumar
UTm Universe transvers mercator, Geographic coordinate system
geoid, planar projection, cylindrical and conical projection, longitudinal, latitude, UTM zones 60 zones
The document provides an overview of map projections, which are mathematical transformations that convert the spherical coordinates on the Earth's surface to planar coordinates that can be represented on a map. It discusses the different types of projections, including cylindrical, conical, and planar projections. It also covers important concepts like datums, ellipsoids, and how different projections preserve properties like shapes, distances, areas, or directions to varying degrees based on their mathematical properties and construction.
This document provides information about basic concepts related to charts used for aviation purposes. It discusses key terms like maps, charts, projections and distortions that occur when representing the spherical Earth on a flat surface. It also describes different types of projections including plane, conical, cylindrical and their characteristics. Specific projections like Mercator and Lambert Conformal are explained in more detail.
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Andreas Schleicher presents PISA 2022 Volume III - Creative Thinking - 18 Jun...EduSkills OECD
Andreas Schleicher, Director of Education and Skills at the OECD presents at the launch of PISA 2022 Volume III - Creative Minds, Creative Schools on 18 June 2024.
This presentation was provided by Rebecca Benner, Ph.D., of the American Society of Anesthesiologists, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
🔥🔥🔥🔥🔥🔥🔥🔥🔥
إضغ بين إيديكم من أقوى الملازم التي صممتها
ملزمة تشريح الجهاز الهيكلي (نظري 3)
💀💀💀💀💀💀💀💀💀💀
تتميز هذهِ الملزمة بعِدة مُميزات :
1- مُترجمة ترجمة تُناسب جميع المستويات
2- تحتوي على 78 رسم توضيحي لكل كلمة موجودة بالملزمة (لكل كلمة !!!!)
#فهم_ماكو_درخ
3- دقة الكتابة والصور عالية جداً جداً جداً
4- هُنالك بعض المعلومات تم توضيحها بشكل تفصيلي جداً (تُعتبر لدى الطالب أو الطالبة بإنها معلومات مُبهمة ومع ذلك تم توضيح هذهِ المعلومات المُبهمة بشكل تفصيلي جداً
5- الملزمة تشرح نفسها ب نفسها بس تكلك تعال اقراني
6- تحتوي الملزمة في اول سلايد على خارطة تتضمن جميع تفرُعات معلومات الجهاز الهيكلي المذكورة في هذهِ الملزمة
واخيراً هذهِ الملزمة حلالٌ عليكم وإتمنى منكم إن تدعولي بالخير والصحة والعافية فقط
كل التوفيق زملائي وزميلاتي ، زميلكم محمد الذهبي 💊💊
🔥🔥🔥🔥🔥🔥🔥🔥🔥
Philippine Edukasyong Pantahanan at Pangkabuhayan (EPP) CurriculumMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐄𝐏𝐏 𝐂𝐮𝐫𝐫𝐢𝐜𝐮𝐥𝐮𝐦 𝐢𝐧 𝐭𝐡𝐞 𝐏𝐡𝐢𝐥𝐢𝐩𝐩𝐢𝐧𝐞𝐬:
- Understand the goals and objectives of the Edukasyong Pantahanan at Pangkabuhayan (EPP) curriculum, recognizing its importance in fostering practical life skills and values among students. Students will also be able to identify the key components and subjects covered, such as agriculture, home economics, industrial arts, and information and communication technology.
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐍𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐒𝐜𝐨𝐩𝐞 𝐨𝐟 𝐚𝐧 𝐄𝐧𝐭𝐫𝐞𝐩𝐫𝐞𝐧𝐞𝐮𝐫:
-Define entrepreneurship, distinguishing it from general business activities by emphasizing its focus on innovation, risk-taking, and value creation. Students will describe the characteristics and traits of successful entrepreneurs, including their roles and responsibilities, and discuss the broader economic and social impacts of entrepreneurial activities on both local and global scales.
3. The earth is a spheroid
The best model of the earth is a globe
Drawbacks:
•not easy to carry
•not good for making
planimetric measurement
(distance, area, angle)
17. Map projections always introduce error and
distortion
Distortion may be minimized in one or more
of the following properties:
o Shape … conformal
o Distance … equidistant
o Direction … true direction
o Area … equal area
18. y)
(x,
y)
(x, f
f
input output
unprojected projected
angles (lat/long) Cartesian coordinates
Exactly what are map projections?
Sets of mathematical equations that convert coordinates
from one system to another
19. How do projections work on a programmatic
level?
o each set of "coordinates" is transformed using a specific projection
equation from one system to another
o angular measurements can be converted to Cartesian coordinates
o one set of Cartesian coordinates can be converted to a different
measurement framework
Projection, zone, datum (units) X Y
geographic, NAD27 (decimal
degrees)
-122.35° 47.62°
UTM, Zone 10, NAD27 (meters) 548843.5049 5274052.0957
State Plane, WA-N, NAD83 (feet) 1266092.5471 229783.3093
20. How does ArcGIS handle map projections in
data frames?
o Project data frames to see or measure features under
different projection parameters
o Applying a projection on a data frame projects data “on
the fly.”
o ArcGIS’s data frame projection equations can handle any
input projection.
o However, sometimes on-the-fly projected data do not
properly overlap.
21. Applying a projection to a data frame is like putting
on a pair of glasses
You see the map differently, but the data have
not changed
22. How does ArcGIS handle map projections
for data?
Projecting data creates a new data set on the file
system
Data can be projected so that incompatibly projected
data sets can be made to match.
ArcGIS’s projection engine can go in and out of a large
number of different projections, coordinate systems, and
datums.
24. Examples of different projections
Albers
(Conic)
Shape Shape along the standard parallels is accurate and minimally distorted in the region between the
standard parallels and those regions just beyond. The 90-degree angles between meridians and
parallels are preserved, but because the scale along the lines of longitude does not match the scale
along lines of latitude, the final projection is not conformal.
Area All areas are proportional to the same areas on the Earth.
Direction Locally true along the standard parallels.
Distance Distances are best in the middle latitudes. Along parallels, scale is reduced between the standard
parallels and increased beyond them. Along meridians, scale follows an opposite pattern.
25.
26. Examples of different projections
Lambert
Azimuthal
Equal
Area
(Planar)
Shape Shape is true along the standard parallels of the normal aspect (Type 1), or the standard lines of the
transverse and oblique aspects (Types 2 and 3). Distortion is severe near the poles of the normal aspect
or 90° from the central line in the transverse and oblique aspects.
Area There is no area distortion on any of the projections.
Direction Local angles are correct along standard parallels or standard lines. Direction is distorted elsewhere.
Distance Scale is true along the Equator (Type 1), or the standard lines of the transverse and oblique aspects
(Types 2 and 3). Scale distortion is severe near the poles of the normal aspect or 90° from the central
line in the transverse and oblique aspects.
27.
28. Examples of different projections
Mercator
(Cylindrical)
Shape Conformal. Small shapes are well represented because this projection maintains the local angular
relationships.
Area Increasingly distorted toward the polar regions. For example, in the Mercator projection, although
Greenland is only one-eighth the size of South America, Greenland appears to be larger.
Direction Any straight line drawn on this projection represents an actual compass bearing. These true direction
lines are rhumb lines, and generally do not describe the shortest distance between points.
Distance Scale is true along the Equator, or along the secant latitudes.
29.
30. Examples of different projections
Miller
(Cylindrical)
Shape Minimally distorted between 45th parallels, increasingly toward the poles. Land masses are stretched
more east to west than they are north to south.
Area Distortion increases from the Equator toward the poles.
Direction Local angles are correct only along the Equator.
Distance Correct distance is measured along the Equator.
31.
32. Examples of different projections
Mollweide
(Pseudo-
cylindrical)
Shape Shape is not distorted at the intersection of the central meridian and latitudes 40° 44' N and S.
Distortion increases outward from these points and becomes severe at the edges of the projection.
Area Equal-area.
Direction Local angles are true only at the intersection of the central meridian and latitudes 40° 44' N and S.
Direction is distorted elsewhere.
Distance Scale is true along latitudes 40°44' N and S. Distortion increases with distance from these lines and
becomes severe at the edges of the projection.
33.
34.
35. Examples of different projections
Orthographic
Shape Minimal distortion near the center; maximal distortion near the edge.
Area The areal scale decreases with distance from the center. Areal scale is zero at the edge of the
hemisphere.
Direction True direction from the central point.
Distance The radial scale decreases with distance from the center and becomes zero on the edges. The scale
perpendicular to the radii, along the parallels of the polar aspect, is accurate.
36.
37. Examples of different
projections
Robinson
(Pseudo-
cylindrical)
Shape Shape distortion is very low within 45° of the origin and along the Equator.
Area Distortion is very low within 45° of the origin and along the Equator.
Direction Generally distorted.
Distance Generally, scale is made true along latitudes 38° N and S. Scale is constant along any given latitude,
and for the latitude of opposite sign.
39. Coordinates
Features on spherical surfaces are not
easy to measure
Features on planes are easy to measure
and calculate
distance
angle
area
Coordinate systems provide a
measurement framework
41. Lat/long values are NOT Cartesian (X,
Y) coordinates
constant angular deviations do not have
constant distance deviations
1° of longitude at the equator 1° of
longitude near the poles
44. Coordinate systems
Examples of different coordinate/projection
systems
State Plane
Universal Transverse Mercator (UTM)
45. Coordinate systems
State Plane
Codified in 1930s
Use of numeric zones for shorthand
SPCS (State Plane Coordinate System)
FIPS (Federal Information Processing System)
Uses one or more of 3 different projections:
Lambert Conformal Conic (east-west orientation )
Transverse Mercator (north-south orientation)
Oblique Mercator (nw-se or ne-sw orientation)
46. Coordinate systems
Universal Transverse Mercator
(UTM)
Based on the Transverse
Mercator projection
60 zones (each 6° wide)
false eastings
Y-0 set at south pole or equator
50. Datums
A system that allows us to place a coordinate
system on the earth’s surface
Initial point
Secondary point
Model of the earth
Known geoidal separation at
the initial point
51. Datums
Commonly used datums in North America
North American Datum of 1927 (NAD27)
NAD83
World Geodetic System of 1984 (WGS84)
52. Projecting spatial data sets
UTM 36
UTM 34
Lake Victoria is not in central Africa
Used for going between projections
Source data sources may not be compatible
53. Projecting spatial data sets
Used for going between projections
• Data sets are now compatible
Lake Victoria really is in east Africa
both are
now UTM 34