Teach you how to create an offline map on your mobile phone

1. What is an offline map?

Generally, the map service is connected to a network cable and obtains the connected map service from map service providers such as Google. That is, map data is downloaded from the network in real time and displayed on mobile phones and other devices, this method of map should be called the online map service, which does not exist when it leaves the network. for mobile phones, in addition to the network, it also requires the support of the base station signal, where there is no signal, naturally, this map service does not exist. Therefore, the online map service has certain limitations on field operations, adventure, and tourism. It can only be used in cities with signals or networks.

An offline map, as its name implies, is a map without network connections. When you put a paper map around you, you do not need to view the map online, you only need to open the paper to view. Similarly, when you move the map data around, you do not need to access the Internet to conveniently view the map, locate the location, and identify the direction of action. If there is a terrain map or satellite map along with the traffic map, how big is it for field workers and travel explorers. This article introduces how to create offline map on mobile phones. It is to teach you how to create maps of various types in any area of interest in the world, including road traffic maps and topographic maps, satellite map and road Satellite Comprehensive map. When you put these maps around, it will be of great help for your trip. Now, let's talk about a basket of things. Next we will start to create our own map step by step.

2. Create a mobile phone offline Map

To create an offline map, you must first have a production tool, but don't be nervous. This tool is free of charge. You can download it online and query the "offline map production tool for mobile phones" on csdn ", you can find the download path for this tool. If you do not find it, you can also call the ch2zh1@tom.com he can send this tool to you. Here we assume that you have obtained the tool program.

This tool can run directly without installation. As long as your PC is connected to the Internet, it can run normally. However, we recommend that you put this program in a separate folder, such as E:/GMAP. Note: run this program in windows. The recommended operating system is Windows XP, windows, or an updated version. After installing this tool, you can start creating a map.

First, start the program, such:

I set Shenyang as the initial screen center because I am in Shenyang. Sorry. If this screen is not displayed, but a white square is displayed, please wait for a while and the program is downloading the initial map screen from the Internet. Note that the image is not downloaded every time, but only once for each desired image.

After the initial Screen Preparation is complete, you can move the map to the area you are interested in. During the map movement process, the program continuously downloads new map images. Therefore, for new areas, the movement process will be intermittent. You can repeat the operation and drag it at will. As long as your machine's hard disk is large enough, you can put the whole world in your machine.

The following describes the meaning of each data on the program interface. You can also view the help of the program to understand their meaning.

Center position: the longitude and latitude of the cross-line point in the center of the map.

Image size: the size of the current map image is measured in pixels.

Current position: the longitude and latitude of the mouse point

Current magnification: Current scaling factor of the map. The minimum is 5 and the maximum is 17.

Note: The button next to the current magnification is the button for setting the magnification. After selecting a magnification, use this button to change the magnification of the map.

View map type: select the displayed map type. You can give it a try.

The following parameters are used to create an offline map.

Maximum zoom-in factor: the maximum zoom-in factor required by the offline map, which cannot be smaller than the current zoom-in factor. You can select from the drop-down list. The maximum value is 17.

Include map type: the map type included in the connected map. Use the check box to select the specified map type. The generated map data contains the specified map type.

The following is the generation operation.

Generate mobile phone Map button: Start to download map data according to the specified parameters (map center coordinates, magnification, map type. The program calculates the number of map data images to be downloaded, and a dialog box is displayed, showing the parameters and data volume of the map to be generated (data volume of a single type map ), click "OK" to start generating data. a progress bar is displayed below the button, indicating the progress of data download. After the progress bar is displayed, a Cancel button can be used to cancel generating data. The resumable upload function is supported for downloading map data. Therefore, when you cancel the download in the middle of the process, the data that has been downloaded will still be valid at the next production time and will be downloaded from the breakpoint. Generally, the map data is relatively large. You can use the interrupted function to download the data multiple times separately.

Help button: displays the operation help text of the program.

Save parameter button: Save the selection parameter of the map to be generated to the file, so that when you download and generate the map later, the generated parameters will be restored directly from the file.

Open parameter button: Open the saved map selection parameter file and restore the parameter settings for the map generation operation.

Below are the system parameter settings.

Setting button: Set the startup and running parameters of the system, including:

1. Map error: there is a certain error between the geographic coordinates indicated by Google maps and the actual geographic coordinates. Therefore, an error correction is required during GPS positioning. Through this error correction process, the positioning Deviation Caused by map accuracy can be ruled out.

The error setting method is as follows:

First, select a marked building on the map near the center of the map area to be generated, and use the actual GPS device to record the actual geographical coordinate, longitude, and latitude value of the tag, find the tag on the map, move the mouse over the tag, record the latitude and longitude data value of the current position of the mouse, and calculate the error using the following formula.

Error value = actual latitude and longitude value-currently displayed latitude and longitude value

Enter this error value in the map precision error box of the corresponding type, and then click the setting button on the overview box. Note: The error value may be different from the input value after being processed by the program, because the system has the default error value.

After the error is set, you can move the mouse to check whether the coordinates of the map tag are consistent with the actual coordinates, so as to verify the correctness of the settings.

Note: This error value varies according to different regions. Although the difference is not big, it still affects precise positioning. This error value is taken to the generated map, therefore, before creating a map, you must confirm the error of each type of map.

2. Set the initial position (map center point at startup)

In the initial position setting box, directly enter the expected map center coordinate value, and then press the set button on the overview box. The next time you start the system, the new coordinate point will be taken as the map center.

3. Initial magnification (5 by default)

Set the magnification when the program starts. The default value is 5. You can select from the drop-down list. Then, press the set button.

The following describes the View button function.

View button: Check whether the generated map data meets the requirements, for example, whether the central position is correct, the MAP range is appropriate, and whether the map type exists. It is not suitable for re-generation, and the downloaded data will not be wasted.

The following is a specific example to illustrate the map generation process.

1. Start the program,

2. Select a region, for example, Lhasa. Drag the map with the mouse (Press and hold the left mouse button to move the mouse) to Lhasa,

3. Select the current magnification to 11 to further determine the location of the map center. In the current magnification drop-down box, select 11, and then click the setting button next to it,

4. If you do not see any landmark, zoom in until you find the central landmark.

After we zoom in to 15 times, we select Kuala Lumpur square as the map center. At this time, we can set the map error based on the actual coordinates of the specific location. Suppose we have set the map error value according to the steps.

5. Select the desired map type for comparison and check whether the error accuracy is correct.

Here we select a road satellite map. We can see that because we have not set the correct error, the center position on the two charts does not refer to the same location. Therefore, it is very important to set errors when creating an offline map.

6. After determining the center and setting the error of each type of map, we can determine the MAP range. First, reduce the magnification until all the required areas are included in the display window.

When we set the magnification to 13, the city of Lhasa will be completely included. At this time, we can determine that the minimum magnification of the map should be 13. Note: When zooming a map, you must select the center. The center is not necessarily the location of the landmark. You can select either the regional center or the landmark as the center.

7. Select the maximum magnification. You can use the current magnification settings to zoom in the map step by step, or directly zoom in to the maximum of 17. Check whether such a detailed map is required. Until you select the most satisfactory magnification. And select it as the maximum magnification. At the same time, the current magnification is restored to 13 (the minimum magnification we have determined ).

8. Select the map type to be included. Note: Generally, the satellite map and the Integrated Satellite Road Map are the same. Therefore, you can select a type to save data storage space. Here we select the road chart and the comprehensive chart.

9. We finally decided that the parameters for generating the map are:

Center Location: 91.11979/29.65263

Minimum magnification: 13

Maximum magnification: 16

Include type: Road, comprehensive

Click the Save button below the Help button to save the parameter to the file. In future operations, you can

Use the parameter file to restore the generation status. You do not have to reset it every time.

10. Now the map is generated. This is a data download process. Press the generate mobile phone Map button to bring up a confirmation dialog box,

Zoom level: indicates that the generated map has a total of four scales, from 13 to 16.

Map size: map size with minimum Scaling (pixel unit)

Max map size: map size with maximum Scaling

Total number of map blocks: number of images contained in a map of the same type. Multiple types must be multiplied by the number of types.

Select the OK button to start generating the operation,

11. You can use the button next to the progress bar to interrupt the generation operation at any time. Then, use the saved parameter file to restore the generation of parameters and continue the generation operation. All downloaded data remains valid.

12. After the generation operation is complete, you can use it by saving the data as a file.

The file name is gmap_ls,

13. view the operation and view the generated map effect. Open the data file, gmap_ls,

You can drag the map to view the range, change the type and zoom in/out ratio, and check whether the map meets the requirements. If not, you can change the parameters. All downloaded data remains valid and does not need to be downloaded again.

Note: When you use the map parameter file to restore a map, you must check whether the current error settings are correct, to ensure the correctness of the generated map error.

3. How to Use offline map of mobile phone

After you download the mobile phone offline map GPS or the mobile phone offline map application on mm (China Mobile Online Store), you can use your own map data. The method is to connect the mobile phone to the computer. After synchronization, copy the created map data to the gmapmobile directory under the program file, run the offline Map Program of the mobile phone, and select the map in the map attribute bar, OK.

4. What do you feel?

After your mobile phone GPS is activated, you can mark your current location on the map. If the error calculated during map creation is accurate enough, your location accuracy is only the GPS precision. By comparing the road map and the comprehensive map, you can understand the current location and the surrounding environment. Only the road traffic map may guide the trip in the city, but in the mountains, the wild, scenic spots, you may need a comprehensive map to understand the surrounding terrain environment, and you need to switch the map type at any time to view the approximate orientation. As long as your mobile phone has electricity, you can always find the correct direction of action through GPS.