Definitions of coordinate transformation, geographic coordinates, and projection coordinates in ARCGIS

1. Dynamic projection (ArcMap)

The so-called dynamic projection refers to the spatial reference of Data In ArcMap or the coordinate system is the coordinate system of the file first loaded to the current workspace by default, and then the added Data, if it is different from the coordinate system of the current workspace, ArcMap automatically performs a projection transformation and converts the added data projection to the current coordinate system! However, the data stored in the data file has not changed, but the display form has changed! So Dynamic projection! The most obvious example of this is that when you Export Data, you will choose to press this layer's source data (the coordinate system of the Data source is exported ), export Data according to the Data (the coordinate system of the current Data framework!

2. ArcCatalog)

We all know that a coordinate system for data can be described in ArcCatalog! Right-click the data and choose Properties> XY Coordinate System. Here, you can Select a Coordinate System for the data by using the modify, Select, and Import methods! However, many people think that the data itself has changed after the change! But not like this! The abbreviated information corresponds to the. aux file of the data! If you delete the file, the Unknown will still be displayed when you re-view the file attributes! The change here is just a description of the data, just like the basic information registration card you entered in school. I changed the description but it didn't change you! Therefore, the coordinates of the data stored in the data file are not truly projected and changed to the coordinate system you want to change! However, this description of the data is also very important. If you get a data, we can see from the coordinates displayed under ArcMap, such as the plane coordinates under the projection coordinate system, but I don't know what projection is based on! Therefore, you cannot perform further operations on the data! For example: Projection Transformation Operation! Because you don't know which projection to start transformation! Therefore, you must correct the description of the coordinate system in the data attribute in ArcCatalog!

3. ArcToolBox)

As mentioned above, what should we do if we really need to change the data, that is, doing projection transformation! Go to ArcToolBox> Data Management Tools> Projections and Transformations! The following tools are most commonly used in this toolset:

1. Define Projection

2. Feature-> Project

3. Raster-> Project Raster

4. Create Custom Geographic Transformation

When the data does not have any space reference, it is displayed as Unknown! Define Projection is used to Define a Coordinate System for the data, and then the data is projected and transformed using Feature-> Project or Raster-> Project Raster tool! Due to the frequent use of the projection coordinate system in China, Beijing 54 and Xi'an 80! When the two coordinate systems are transformed to other coordinate systems, a Geographic Transformation is usually required because the Datum has changed! Here we will use the conversion 3 parameter and the conversion 7 parameter! The conversion parameters in our country are confidential! Therefore, you can calculate the data by yourself or ask for it from the National Surveying and Mapping Department when purchasing the data! After knowing the conversion parameters, you can use the Create Custom Geographic Transformation Tool to define a Geographic Transformation method. You can select the GEOCENTRIC_TRANSLATION and COORDINATE _ methods based on the 3 or 7 parameters! This completes the projection transformation of data! The coordinates of the data have changed! Of course, this projection transformation can also be implemented In ArcMap by changing the Coordinate System of Data, just export Data according to the Data Coordinate System after completion!

 

Method 1:

Conversion In Arcmap:

1. Load the data to be converted, with the longitude and latitude in the lower right corner.

2. Click View-Data box Attribute-Coordinate System

3. Import or select the correct coordinate system. The coordinates are also displayed in the lower right corner. But the data hasn't changed.

4. Right-click the layer-data-export data

5. Select the second (data framework), output path, and OK.

6. This method is similar to projection transformation.

 

Method 2:

Convert in forestar:

1. Create layer aa with the correct coordinate system and Range

2. Open the data to be converted. The layer output is the same as the original type, named aa, and appended.

 

Method 3:

Conversion in ArcToolbox:

1. Management Tool-projection (project): select the input/output path and the output Coordinate System

2. The premise is that the raw data must have a projection.

Differences between geographic coordinate system and projection Coordinate System

1. First, understand the Geographic coordinate system (Geographic coordinate system). Geographic coordinate system
The geographic coordinate system is a MAP storage unit. Apparently, Geographic coordinate syst
Em is a spherical coordinate system. How do we store the digital information on the earth on the Spherical Coordinate System?
What about it? The earth is an irregular elliptical shape. How can we store data information on the elliptical sphere in a scientific way? This requirement
We found such an elliptical body. Such an elliptical body has the following features: it can be quantified. Has a long half axis, short
Half Axis, eccentric heart rate. The following rows are the result of.
Spheroid: craovsky_1940
Semimajor Axis: 6378245.000000000000000000
Semiminor Axis: 6356863.018773047300000000
Inverse Flattening (flat rate): 298.300000000000010000
However, with this elliptical body, it is not enough. You still need a to locate the elliptical body. Description in Coordinate System
You can see this line:
Datum: D_Beijing_1954
D_ing_1954 indicates that the is D_Beijing_1954.
--------------------------------------------------------------------------------
With the basic conditions of Spheroid and Datum, the geographic coordinate system can be used.
Complete parameters:
Alias:
Abbreviation:
Remarks:
Angular Unit: Degree (0.017453292519943299)
Prime Meridian (start longitude): Greenwich (0.000000000000000000)
Datum (): D_Beijing_1954
Spheroid (refer to the elliptical body): kraovsky_1940
Semimajor Axis: 6378245.000000000000000000
Semiminor Axis: 6356863.018773047300000000
Inverse Flattening: 298.300000000000010000
2. The next step is Projection coordinate system (Projection coordinate system). First, let's take a look at the Projection sitting
Parameters in the system.
Projection: Gauss_Kruger
Parameters:
False_Easting: 500000.000000
False_normal: 0.000000
Central_Meridian: 117.000000
Scale_Factor: 1.000000
Latitude_Of_Origin: 0.000000
Linear Unit: Meter (1.000000)
Geographic Coordinate System:
Name: GCS_Beijing_1954
Alias:
Abbreviation:
Remarks:
Angular Unit: Degree (0.017453292519943299)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: D_Beijing_1954
Spheroid: craovsky_1940
Semimajor Axis: 6378245.000000000000000000
Semiminor Axis: 6356863.018773047300000000
Inverse Flattening: 298.300000000000010000
From the parameters, we can see that every projection Coordinate System must have Geographic Coordinate System.
The projection coordinate system is essentially a plane coordinate system, and its map unit is usually meters.
So why do the parameters of the coordinate system exist in the projection coordinate system?
At this time, we need to explain the significance of projection: the process of converting spherical coordinates into plane coordinates is called projection.
Now, the projection conditions are displayed:
A. Spherical Coordinates
B. conversion process (that is, algorithm)
That is to say, to obtain the projection coordinate, you must have a "used" spherical coordinate of the projection before using the algorithm.
Go to projection!
That is, each Coordinate System must have the Geographic Coordinate System parameter.
3. Many of the textbooks we have seen have many names for the coordinate system, which can be attributed to the preceding two types of projection.
. This includes our common "non-earth projection coordinate system ".) :
__________________
Geodetic Coordinate. The position of the ground point P is represented by the Land longitude L, the land latitude B, and the Earth height H. When the point is on the reference elliptical sphere, it is expressed only by the longitude and latitude of the Earth. The longitude of the earth is the angle between the Earth's radial plane and the starting Earth's radial plane. the latitude of the earth is the angle between the normal and the equator of the point. The height of the earth is the distance from the ground point along the normal to the reference elliptical sphere.
Square grid: A square grid composed of two parallel lines parallel to the projection coordinate axis. Because the vertical line and the horizontal line of coordinates are drawn every kilometer, it is called the square internal network. Because the square internal line is also a coordinate network cable parallel to the Cartesian axis, it is also called the Cartesian coordinate network.
On a topographic map with a scale of-, the ing line is displayed only in the form of a graph contour and the corresponding degree is indicated at the graph angle. In order to encrypt a graph into a network when using it, there is also an encrypted shard line between the internal and external charts (the Scheme is called "index band "), if necessary, a short-line connection can constitute an encrypted latitude and longitude network. On the 50 thousand topographic map, in addition to the Intranet encrypted partition on the internal chart, there is also a cross line for encryption.
China's-topographic map directly draws the latitude and longitude network on the drawing, and there is also a short line of encryption for the latitude and longitude network.
The coordinate system of the Cartesian coordinate network uses the straight line after the central longitude line projection as the X axis, the straight line after the equator projection as the Y axis, and their point of intersection as the coordinate origin. In this way, four quadrants appear in the coordinate system. The X-axis is positive to the north and negative to the south from the equator. The X-axis is positive to the east and negative to the west from the central Meridian.
Although we can think that the square net is the Cartesian coordinate, the earth coordinate is the spherical coordinate. However, we often see the square net and latitude and longitude net on a topographic map. We are used to calling the latitude net as the earth coordinate. At this time, the earth coordinate is not the spherical coordinate, she is the same as Fang Li's projection (generally Gaussian), and is also a plane coordinate.

 

Reprinted from: http://www.cnblogs.com/aooyu/archive/2010/06/25/1765037.html

1. Dynamic projection (ArcMap)

The so-called dynamic projection refers to the spatial reference of Data In ArcMap or the coordinate system is the coordinate system of the file first loaded to the current workspace by default, and then the added Data, if it is different from the coordinate system of the current workspace, ArcMap automatically performs a projection transformation and converts the added data projection to the current coordinate system! However, the data stored in the data file has not changed, but the display form has changed! So Dynamic projection! The most obvious example of this is that when you Export Data, you will choose to press this layer's source data (the coordinate system of the Data source is exported ), export Data according to the Data (the coordinate system of the current Data framework!

2. ArcCatalog)

We all know that a coordinate system for data can be described in ArcCatalog! Right-click the data and choose Properties> XY Coordinate System. Here, you can Select a Coordinate System for the data by using the modify, Select, and Import methods! However, many people think that the data itself has changed after the change! But not like this! The abbreviated information corresponds to the. aux file of the data! If you delete the file, the Unknown will still be displayed when you re-view the file attributes! The change here is just a description of the data, just like the basic information registration card you entered in school. I changed the description but it didn't change you! Therefore, the coordinates of the data stored in the data file are not truly projected and changed to the coordinate system you want to change! However, this description of the data is also very important. If you get a data, we can see from the coordinates displayed under ArcMap, such as the plane coordinates under the projection coordinate system, but I don't know what projection is based on! Therefore, you cannot perform further operations on the data! For example: Projection Transformation Operation! Because you don't know which projection to start transformation! Therefore, you must correct the description of the coordinate system in the data attribute in ArcCatalog!

3. ArcToolBox)

As mentioned above, what should we do if we really need to change the data, that is, doing projection transformation! Go to ArcToolBox> Data Management Tools> Projections and Transformations! The following tools are most commonly used in this toolset:

1. Define Projection

2. Feature-> Project

3. Raster-> Project Raster

4. Create Custom Geographic Transformation

When the data does not have any space reference, it is displayed as Unknown! Define Projection is used to Define a Coordinate System for the data, and then the data is projected and transformed using Feature-> Project or Raster-> Project Raster tool! Due to the frequent use of the projection coordinate system in China, Beijing 54 and Xi'an 80! When the two coordinate systems are transformed to other coordinate systems, a Geographic Transformation is usually required because the Datum has changed! Here we will use the conversion 3 parameter and the conversion 7 parameter! The conversion parameters in our country are confidential! Therefore, you can calculate the data by yourself or ask for it from the National Surveying and Mapping Department when purchasing the data! After knowing the conversion parameters, you can use the Create Custom Geographic Transformation Tool to define a Geographic Transformation method. You can select the GEOCENTRIC_TRANSLATION and COORDINATE _ methods based on the 3 or 7 parameters! This completes the projection transformation of data! The coordinates of the data have changed! Of course, this projection transformation can also be implemented In ArcMap by changing the Coordinate System of Data, just export Data according to the Data Coordinate System after completion!

 

Method 1:

Conversion In Arcmap:

1. Load the data to be converted, with the longitude and latitude in the lower right corner.

2. Click View-Data box Attribute-Coordinate System

3. Import or select the correct coordinate system. The coordinates are also displayed in the lower right corner. But the data hasn't changed.

4. Right-click the layer-data-export data

5. Select the second (data framework), output path, and OK.

6. This method is similar to projection transformation.

 

Method 2:

Convert in forestar:

1. Create layer aa with the correct coordinate system and Range

2. Open the data to be converted. The layer output is the same as the original type, named aa, and appended.

 

Method 3:

Conversion in ArcToolbox:

1. Management Tool-projection (project): select the input/output path and the output Coordinate System

2. The premise is that the raw data must have a projection.

Differences between geographic coordinate system and projection Coordinate System

1. First, understand the Geographic coordinate system (Geographic coordinate system). Geographic coordinate system
The geographic coordinate system is a MAP storage unit. Apparently, Geographic coordinate syst
Em is a spherical coordinate system. How do we store the digital information on the earth on the Spherical Coordinate System?
What about it? The earth is an irregular elliptical shape. How can we store data information on the elliptical sphere in a scientific way? This requirement
We found such an elliptical body. Such an elliptical body has the following features: it can be quantified. Has a long half axis, short
Half Axis, eccentric heart rate. The following rows are the result of.
Spheroid: craovsky_1940
Semimajor Axis: 6378245.000000000000000000
Semiminor Axis: 6356863.018773047300000000
Inverse Flattening (flat rate): 298.300000000000010000
However, with this elliptical body, it is not enough. You still need a to locate the elliptical body. Description in Coordinate System
You can see this line:
Datum: D_Beijing_1954
D_ing_1954 indicates that the is D_Beijing_1954.
--------------------------------------------------------------------------------
With the basic conditions of Spheroid and Datum, the geographic coordinate system can be used.
Complete parameters:
Alias:
Abbreviation:
Remarks:
Angular Unit: Degree (0.017453292519943299)
Prime Meridian (start longitude): Greenwich (0.000000000000000000)
Datum (): D_Beijing_1954
Spheroid (refer to the elliptical body): kraovsky_1940
Semimajor Axis: 6378245.000000000000000000
Semiminor Axis: 6356863.018773047300000000
Inverse Flattening: 298.300000000000010000
2. The next step is Projection coordinate system (Projection coordinate system). First, let's take a look at the Projection sitting
Parameters in the system.
Projection: Gauss_Kruger
Parameters:
False_Easting: 500000.000000
False_normal: 0.000000
Central_Meridian: 117.000000
Scale_Factor: 1.000000
Latitude_Of_Origin: 0.000000
Linear Unit: Meter (1.000000)
Geographic Coordinate System:
Name: GCS_Beijing_1954
Alias:
Abbreviation:
Remarks:
Angular Unit: Degree (0.017453292519943299)
Prime Meridian: Greenwich (0.000000000000000000)
Datum: D_Beijing_1954
Spheroid: craovsky_1940
Semimajor Axis: 6378245.000000000000000000
Semiminor Axis: 6356863.018773047300000000
Inverse Flattening: 298.300000000000010000
From the parameters, we can see that every projection Coordinate System must have Geographic Coordinate System.
The projection coordinate system is essentially a plane coordinate system, and its map unit is usually meters.
So why do the parameters of the coordinate system exist in the projection coordinate system?
At this time, we need to explain the significance of projection: the process of converting spherical coordinates into plane coordinates is called projection.
Now, the projection conditions are displayed:
A. Spherical Coordinates
B. conversion process (that is, algorithm)
That is to say, to obtain the projection coordinate, you must have a "used" spherical coordinate of the projection before using the algorithm.
Go to projection!
That is, each Coordinate System must have the Geographic Coordinate System parameter.
3. Many of the textbooks we have seen have many names for the coordinate system, which can be attributed to the preceding two types of projection.
. This includes our common "non-earth projection coordinate system ".) :
__________________
Geodetic Coordinate. The position of the ground point P is represented by the Land longitude L, the land latitude B, and the Earth height H. When the point is on the reference elliptical sphere, it is expressed only by the longitude and latitude of the Earth. The longitude of the earth is the angle between the Earth's radial plane and the starting Earth's radial plane. the latitude of the earth is the angle between the normal and the equator of the point. The height of the earth is the distance from the ground point along the normal to the reference elliptical sphere.
Square grid: A square grid composed of two parallel lines parallel to the projection coordinate axis. Because the vertical line and the horizontal line of coordinates are drawn every kilometer, it is called the square internal network. Because the square internal line is also a coordinate network cable parallel to the Cartesian axis, it is also called the Cartesian coordinate network.
On a topographic map with a scale of-, the ing line is displayed only in the form of a graph contour and the corresponding degree is indicated at the graph angle. In order to encrypt a graph into a network when using it, there is also an encrypted shard line between the internal and external charts (the Scheme is called "index band "), if necessary, a short-line connection can constitute an encrypted latitude and longitude network. On the 50 thousand topographic map, in addition to the Intranet encrypted partition on the internal chart, there is also a cross line for encryption.
China's-topographic map directly draws the latitude and longitude network on the drawing, and there is also a short line of encryption for the latitude and longitude network.
The coordinate system of the Cartesian coordinate network uses the straight line after the central longitude line projection as the X axis, the straight line after the equator projection as the Y axis, and their point of intersection as the coordinate origin. In this way, four quadrants appear in the coordinate system. The X-axis is positive to the north and negative to the south from the equator. The X-axis is positive to the east and negative to the west from the central Meridian.
Although we can think that the square net is the Cartesian coordinate, the earth coordinate is the spherical coordinate. However, we often see the square net and latitude and longitude net on a topographic map. We are used to calling the latitude net as the earth coordinate. At this time, the earth coordinate is not the spherical coordinate, she is the same as Fang Li's projection (generally Gaussian), and is also a plane coordinate.

 

Reprinted from: http://www.cnblogs.com/aooyu/archive/2010/06/25/1765037.html