GIS basic software and operation (III.)

Original GIS basic software and operation (III.)

Exercise three, Map registration operation

1. Map registration for topographic maps with no coordinate information (image format)
2. Use of the editor (point features, line features, digitizing of polygon features)

This example mainly introduces how to add coordinate information to topographic map (picture format) without coordinate information. Picture file format with coordinate information has TIFF
and grid format (this situation can be skipped 1, 2, 3 steps, starting with the 4th step), the rest, such as JPG, BMP, PNG
And so on with no coordinate information.

The 1th step is to determine the target coordinate information

Open the topographic map image to see the coordinate datum information, scale, and coordinate range of the topographic map. "Coordinate datum information" is the geographic coordinate system of the topographic map, at the lower left of the picture, the "scale bar" in the lower side of the map,
The projection method of the topographic map is determined, and the large scale topographic map in China adopts
Gauss-kruger (Gauss-gram Gauss–krüger)
The "coordinate range" determines the band number of the Gaussian-gram Gauss–krüger projection (3 degrees or
6 degrees) and the central meridian. Note: 1:10,000 with 3 degree with projection, 1:25,000-500,000 with projection with 6 degrees.

Read the graph to know:

2nd Step setting the properties of the data frame

Open it
ARCMAP, loading topographic map file "70011-1.tif", right-click Layer "Layers"-coordinate system "coordinate
Systems "-Projection coordinate system" projected coordinate systems "-" Gauss
Kruger "-" Xian 1980 "-" Xian 1980 3 degree GK CM
102E, select General tab, set map unit "Units".

The 3rd step defines the projection.

You can see that the coordinate range of the layer has been corrected to the Gaussian coordinate system, but the data is implicitly with coordinate information and needs to be defined after the projection
To have display coordinate information. Open Data Management Tools | Projection and Transformation | Define projection tool, enter number
According to the set or feature class set to "70011-1.tif", click on the right Coordinate system button to open the Spatial Reference Properties dialog box; Click "Select" and select the projected coordinate system "projected
Coordinate Systems "-" Gauss Kruger "-" Xian 1980 "-" Xian 1980 3 degree
GK CM 102E "; Because the central meridian of the topographic map in this example is 102.65625°, you need to modify
Default to 102E
Coordinate information for the Central meridian; Click the "Modify" button to set the project name "NewProject",
The central Meridian value is changed to
102.65625°. OK, execute the definition projection tool and get the topographic map that defines the projection.

4th step Setting up a registration connection

Open it
ARCMAP, loading topographic map image data. Right-click in the blank of the menu bar to add a georeferencing toolbar. First, the "automatic correction" under the Georeferencing tool bar is canceled;

Use the Add Control Point tool to register the corner points;

After tapping a corner point, right-click anywhere, select "Enter latitude and longitude",
1 in the latitude and longitude coordinate input, set up the connection relationship of the four points in turn. Note: If the inner contour is not horizontal or vertical, the picture must be flattened before registration can be performed. This example has been flattened.

The 5th step is to view the connection table.

Click the View Connection Table button in the toolbar to open the Connection table, which lists the pixel coordinates from the
The control point correspondence of the system (raw) to the Gaussian coordinate system (target), the residuals list is empty. In the Join Table dialog box, transform select either "correction" or "first order polynomial (affine)" to
The residual values generated before and after the four-point correction are calculated. Because "correction" is a mandatory transformation method, easy to cause picture correction
Before and after the serious distortion, dislocation and other errors, it is recommended not to use this method, and the first-order polynomial or second-party polynomial and other transformations
The method is to maintain the overall integrity of the image (without dislocation) at the expense of the correction accuracy. In this case, because the control points are four-point points, all include the diagram content, you can consider using the "correction" method.

The 6th step is to perform the image correction.

Select the "Correct" menu under "georeferencing" in the toolbar to save the corrected topographic map as "corrected. tif", formatted as "TIFF", and the cell size is default (in the first order polynomial variable
Method for correction).

7th Step Layering vectorization-Create a line feature layer in Arccatlog

(1) Open Arccatalog. Under the specified directory, right-click, in New, select Personal
Geodatabase ". and modify the name of the Geodatabase database (for example, Test3.mdb).

(2) The following will create a new feature class for the geodatbase, first creating a contour feature class to store contour features. In Arccatalog, right-click Test3 this personal geodatabase and select feature class in New.

(1) Enter the name "contour" of the Created feature class and click Next.

(2) Click Next.

The following will be the key to creating a new feature class for our data, defining the coordinate system, spatial scope, and storing the feature types. And you can add property fields in this.

(1) Click the Shape field. The detailed options are shown in the dialog box, we first click on "Geometry Type" and select the feature type as the type we want (we are now going to create the contour of this feature class, so we should select the line ).

(1) Click the button after the "Spatial reference" option, and in the Spatial Reference Properties dialog box, under the Coordinate system Options page, select the appropriate coordinate systems and click the "Select" button. In (projected
Coordinate systems directory, select Gauss Uger-xian 1980–
XIAN_1980_DEGREE_GK_CM_102E.PRJ). Click Add, now these coordinate system information should look like this:

(1) Below we will create a new attribute field for this data. Elevation, the type is set to Float to store the elevation values for contours.

(1) Click Done so we created a linear feature class.

The 8th step is to extract contour lines on the map and save them in the feature class created above

(1) Switch to ArcMap,
Load the newly created line feature layer into the data frame that contains the georeferenced topographic map, save the document as Ex3.mxd

(2) Open the Editor toolbar, execute start editing command from the Editor drop-down menu, and select the Contour feature class you created earlier. Confirm Editor: Task is-new feature, target-contour, set layer-contour the display symbol is red and set to the appropriate width.

(1) Enlarge the map to a suitable scale, trace a contour from it and interpret its elevation according to the elevation point, and enter the elevation of the High Line of the bar.

(2) One-step practice of other operations of line features, such as the merging of segments, segmentation, editing vertices and other operations

You can refer to the above steps to propose polygon features (such as residents) from the map, and be more familiar with the related operations of Polygon feature editing.

Wang Smooth
Comment posted: 2016-01-14 14:55:54
Updated on: 2016-04-28 21:41:44
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GIS basic software and operation (III.)