GIS implementation method based on PDT interphone

Abstract

The invention discloses a GIS (Geographic Information System) implementation method based on a PDT (Public Digital Trunk) interphone, which solves the problems that on the basis that the hardware scheme of the existing PDT digital trunking interphone is not adjusted, the GIS function can be realized, and the professional can realize the practical functions of navigation, linkage and the like through the GIS function of the interphone when executing tasks in the fields, suburbs and other areas which are easy to get lost. According to the method, the map picture is intercepted, the map is compressed and graded according to the resolution ratio of the PDT interphone, the GIS map storage space is optimized, the GIS function is applied to the PDT interphone, and the map display, positioning, distance measurement and navigation functions are achieved on the interphone through the GIS compression technology according to the map characteristics.

Description

Technical Field

[0001] The invention relates to the technical field of intercom application, and in particular to a GIS implementation method based on a PDT intercom. Background Art

[0002] Professional PDT digital trunking intercoms usually use low-cost embedded processors due to cost, power consumption, processing response time and other reasons. The mainboard memory is usually less than 32M. Existing intercoms basically only have one intercom call function. When professionals perform tasks in the wild, suburbs and other areas where it is easy to get lost, if unexpected situations occur, such as getting lost or falling into a dangerous situation and needing rescue, the intercom call function alone cannot quickly implement rescue actions, which is very inconvenient. The safety of professionals when performing tasks cannot be fully guaranteed and they cannot respond to emergencies. Therefore, it is necessary to implement GIS functions on the intercom without adjusting the existing PDT digital trunking intercom hardware solution and increasing costs, so as to provide effective communication guarantees for professionals to perform tasks in the wild and suburbs, and improve the communication capabilities of search and rescue, navigation, and linkage.

[0003] For example, CN113726705A discloses a PDT intercom with integrated AIS encoding and decoding capability, which includes an antenna, a channel unit, a baseband unit, and a display unit. AIS is GMSK modulation, PDT is 4FSK modulation, the channel unit has high-speed AD sampling capability, and the baseband unit stores the modulation and waveform characteristics of the synchronization word of the AIS mode message and the PDT mode message under high-speed sampling. The intercom contains receiving and transmitting processes. Using the same set of channel machines and baseband units to be compatible with PDT and AIS modes greatly improves the portability of the equipment and effectively increases the standby time. Maritime operators can easily carry the equipment to communicate with PDT or use AIS messages for help. The same channel unit and baseband unit are used to automatically identify the signal mode. Users do not need to switch manually to receive services in both modes, allowing them to focus more on on-site operations and initiate requests for help more easily. However, it still only has a communication function and cannot quickly locate the rescue personnel, resulting in low rescue efficiency. Therefore, a walkie-talkie application method is needed to realize GIS function on the walkie-talkie without increasing the cost, provide effective communication guarantee for professionals to perform tasks in the wild and suburbs, and improve the communication capabilities of search and rescue, navigation, and linkage. Summary of the invention

[0004] The purpose of the present invention is to realize the GIS function without adjusting the existing PDT digital trunking intercom hardware solution, so that professionals can realize practical functions such as navigation and linkage through the GIS function of the intercom when performing tasks in the wild, suburbs and other areas where it is easy to get lost. To solve the above problems, the present invention provides the following technical solutions: A GIS implementation method based on PDT intercom, comprising the following steps: S1. Determine the map display range; S2. Select a suitable range of map levels according to the display resolution of the intercom terminal and capture the map image; S3. Extracting the map feature color from the captured map image bitmap; S4. Dynamically converting the map image into a 1-bit, 2-bit, or 3-bit color map according to the extracted map feature colors; S5. Compress the map image and download it to the intercom terminal for use as a GIS map; S6. The intercom terminal realizes map movement and zooming by changing the positioning point.

[0005] According to the performance of the intercom terminal and taking into account the application scenarios of the intercom, there is no need for a particularly large map range. It is only necessary to store the map range within the used range in the intercom, and the size of the stored map is within the storage space size range of the intercom. The GIS function is added to the hardware solution of the original PDT digital cluster intercom without changing the cost, and the map size is compressed by using map compression technology, which further reduces the space required for storing the map. When the map is displayed, the intercom restores it to 24-bit RGB true color according to the bitmap information to achieve reasonable display of the map, and meets the requirement of ensuring the map display effect without increasing the storage space. It is an optimization solution for the existing PDT digital cluster intercom.

[0006] Preferably, the specific contents of the map level division in step S2 include: Level 1 = 320*240*4 = 38400B, each pixel represents 160*n (n=1, 2, ...)m, and the entire screen display range is 51.2*38.4 square kilometers; Level 2 = (320*2)*(240*2)*4 = 153600B, each pixel represents 80*n (n=1, 2, ...)m, and the entire screen display range is 25.6*19.2 square kilometers; Level 3 = (320*4)*(240*4)*4 = 153600B, each pixel represents 40*n (n=1, 2, ...)m, and the entire screen display range is 12.8*9.6 square kilometers; Level 4 = (320 * 8) * (240 * 8) * 4 = 614400B. Each pixel represents 20 * n (n = 1, 2,... m), and the entire screen display range is 6.4 * 4.8 square kilometers; Level 5 = (320 * 16) * (240 * 16) * 4 = 2457600B. Each pixel represents 10 * n (n = 1, 2,... m), and the entire screen display range is 3.2 * 2.4 square kilometers; where n is the level of zooming in and out of the planned map, and m is the unit of meter.

[0007] According to the screen resolution size, the level N of zooming in and out of the planned map is displayed through N pictures. Taking 5 levels as an example, 5 pictures are required. Under the resolution condition of 320 * 240, the storage space is 320 * 240 * color bit. The final storage space = 320 * 240 * 4 * (1 + 4 + 16 + 64 + 256) ≈ 12.5MB, which can meet the storage requirements of ordinary walkie - talkies.

[0008] Preferably, the specific process of step S3 includes: S301. Determine the map zoom level according to the storage space size of the walkie - talkie; S302. Generate i color vectors C by representing i colors with RGB color components respectively 1 (R C1 G C1 B C1 ), C 2 (R C2 G C2 B C2 )…C i (R Ci G Ci B Ci ); S303. Traverse the pixels of the map within the coverage range, represent the color of the current pixel with RGB, and calculate the differences between the current pixel and the map feature colors C 1 ~C i respectively using the Euclidean distance formula. The smallest value indicates the closest color; S304. Select a reasonable threshold D. When d < D, then this point belongs to the corresponding feature color.

[0009] According to the color characteristics of the map image, there are generally 5 to 7 colors. The color selection should fully consider the buildings and road colors of cities and suburbs, as well as the landforms such as hills, forests, and rivers. It is necessary to extract the color bit close to the map color, otherwise there will be obvious color difference and color unevenness of the map. Through the classification method, the colors similar to the current map image are extracted to generate the image closest to the current map to ensure the best display effect. By setting a reasonable threshold D, the amount of calculation can be reduced, the color noise can be removed, and the operation efficiency can be improved.

[0010] Preferably, the specific contents of step S4 include: S401. After obtaining the characteristic color, the pixels of the map image are divided into at most i groups, and the sum of the number of pixels in each group is S 1 , S 2 …S i , calculate the proportion R of each group of pixels in the entire image, respectively calculated as R 1 , R 2 …R i , the calculation formula of the pixel ratio is as follows: Where R is the sum of the pixels of the characteristic color, and Px is the image pixel; S402. Select the threshold T of each group of color classification points. When the pixel ratio of each group is R<T, it is considered that the characteristic color can be ignored. Select a reasonable threshold T to divide the characteristic colors of the target map into 2 groups, 4 groups, and 7 groups, using 1 bit, 2 bits, and 3 bits respectively, to achieve the ability to dynamically divide the map bit colors according to different map areas. The map size and compression size can be automatically selected according to the selected different areas, and the map can adapt to various environments. It has strong adaptability and is very convenient to use.

[0011] Preferably, the specific content of step S5 includes: referring to the bitmap file format, generating 1-bit, 2-bit, and 3-bit bitmaps for storing maps in the intercom, compressing the map image according to the selected map level, and the compression range is 3.12MB-9.36MB, so as to achieve a significant compression of the map storage space, and then downloading the compressed map to the intercom terminal. Professional PDT digital trunking intercoms usually use low-cost embedded processors due to cost, power consumption, processing response time and other reasons, and the mainboard memory is usually less than 32M. The present invention compresses the map through map compression technology, and the compressed map size ranges from 3.12MB to 9.36MB, which meets the memory size of existing PDT digital trunking intercoms.

[0012] Preferably, the intercom terminal resolution is 320*240, and the GIS map storage size is ≤12.5MB, which meets the memory size of the existing PDT digital trunking intercom.

[0013] Preferably, the calculation formula of the Euclidean distance formula is: Among them, R, G, and B are the pixel data of the current map. Ci , G Ci , B Ci C is the map feature color i Pixel data.

[0014] Preferably, in the storage formats of the 1-bit, 2-bit and 3-bit bitmaps, the values ​​of Bits Per Pixel at the offset address 001C of the bitmap file header are 1, 2 and 3 respectively.

[0015] The beneficial effects of the present invention are: without adjusting the existing PDT digital trunking intercom hardware solution and without increasing the cost, the GIS function is realized on the intercom, providing effective communication guarantee for professionals to perform tasks in the wild and suburbs, and improving the communication capabilities of search and rescue, navigation, and linkage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the overall flow chart of the present invention;

[0017] Figure 2 This is a flow chart of step S3 of the present invention;

[0018] Figure 3 This is a flow chart of step S4 of the present invention. DETAILED DESCRIPTION

[0019] The specific implementation of the technical solution of the present invention is further described below through examples and in conjunction with the accompanying drawings.

[0020] Embodiment 1:

[0021] See also Figure 1 , a GIS implementation method based on PDT intercom, comprising the following steps: S1. Determine the map display range; S2. Select a suitable range of map levels according to the display resolution of the intercom terminal and capture the map image; S3. Extracting the map feature color from the captured map image bitmap; S4. Dynamically converting the map image into a 1-bit, 2-bit, or 3-bit color map according to the extracted map feature colors; S5. Compress the map image and download it to the intercom terminal for use as a GIS map; S6. The intercom terminal realizes map movement and zooming by changing the positioning point.

[0022] According to the performance of the intercom terminal and taking into account the application scenarios of the intercom, there is no need for a particularly large map range. It is only necessary to store the map range within the used range in the intercom, and the size of the stored map is within the storage space size range of the intercom. The GIS function is added to the hardware solution of the original PDT digital cluster intercom without changing the cost. The map compression technology is used to compress the map size, further reducing the space required for storing the map. When the map is displayed, the intercom restores the bitmap information to 24-bit RGB true color for display, thereby realizing a reasonable display of the map and ensuring the effect of map display without increasing the storage space. This embodiment is an optimization solution for the existing PDT digital cluster intercom.

[0023] When in use, first determine the display range of the map according to the use range of the walkie-talkie. After determining the use range of the walkie-talkie, select the appropriate map level according to the display resolution of the walkie-talkie terminal, and then capture the map image of the use range area. The specific process of dividing the map level is as follows: According to the screen resolution, the map is zoomed in and out at level n, and displayed through n pictures. For example, 5 levels require 5 pictures. Under the resolution of 320*240, the storage space is 320*240*bit color bit.

[0024] Level 1 = 320*240*4 = 38400B, each pixel represents 160*n (n=1, 2, ...)m, and the entire screen display range is 51.2*38.4 square kilometers; Level 2 = (320*2)*(240*2)*4 = 153600B, each pixel represents 80*n (n=1, 2, ...)m, and the entire screen display range is 25.6*19.2 square kilometers; Level 3 = (320*4)*(240*4)*4 = 153600B, each pixel represents 40*n (n=1, 2, ...)m, and the entire screen display range is 12.8*9.6 square kilometers; Level 4 = (320*8)*(240*8)*4 = 614400B, each pixel represents 20*n (n=1, 2, ...)m, and the entire screen display range is 6.4*4.8 square kilometers; Level 5 = (320 * 16) * (240 * 16) * 4 = 2457600B. Each pixel represents 10 * n (n = 1, 2,... m), and the entire screen display range is 3.2 * 2.4 square kilometers.

[0025] Storage space = 320 * 240 * 4 * (1 + 4 + 16 + 64 + 256) ≈ 12.5MB, which can meet the storage requirements of ordinary walkie - talkies.

[0026] Then, extract the map feature colors from the intercepted map picture bitmap. The specific process of extracting map feature colors is as follows: First, determine the map zoom level according to the storage space size of the walkie - talkie. Then, represent i colors with RGB color components respectively, and thus generate i color vectors C 1 (R C1 G C1 B C1 ), C 2 (R C2 G C2 B C2 ) … C i (R Ci G Ci B Ci ) and save them in the ROM. Then, read the pixel points of the intercepted map picture, represent the color of the current pixel point with RGB, and use the Euclidean distance formula to calculate the differences d between the current pixel point and the map feature colors C 1 ~C i . The smallest difference means the closest color. Then, select a reasonable threshold D. When d < D, the point belongs to the corresponding feature color. The specific formula of the Euclidean formula used is: Where R, G, B are the pixel point data of the current map, and R Ci , G Ci , B Ci are the pixel point data of the map feature color C i .

[0023] After extracting the map feature colors, dynamically convert the map picture into 1 - bit, 2 - bit, and 3 - bit color bitmaps. Divide the pixel points of the map picture into at most i groups, and the sum of the number of pixel points in each group is S 1 , S 2 …S i . Calculate the proportion R of each group of pixel points in the pixel points of the whole picture, and calculate them respectively as R 1 , R 2 …R i , The calculation formula for the proportion of the said pixel points is as follows: Where R is the sum of the pixels of the characteristic color, and Px is the image pixel; Then select the threshold T of each group of color classification points. When the pixel ratio of each group is R<T, it is considered that the characteristic color can be ignored. Select a reasonable threshold T and divide the characteristic colors of the target map into 2 groups, 4 groups, and 7 groups, using 1 bit, 2 bits, and 3 bits respectively. This realizes the ability to dynamically divide the map bit colors according to different map areas. The storage format of 1-bit, 2-bit, and 3-bit bitmaps, and the values ​​of Bits Per Pixel at the offset address 001C in the bitmap file header are 1, 2, and 3 respectively.

[0027] After dynamically converting the map image into a 1-bit, 2-bit, or 3-bit color image, the map is compressed according to the selected map zoom level, and then the compressed map is stored in the ROM of the intercom terminal through information transmission methods such as Ethernet or Bluetooth. When the map needs to be viewed, the intercom terminal directly reads the saved map data from the ROM and displays it on the display screen. It can also display its location in real time through satellite. When it moves, the map can be moved and zoomed through changes in the positioning point, making it easier to view the map.

[0028] Embodiment 2: This embodiment provides a GIS implementation method for a PDT walkie-talkie with a GIS map range covering 51.2*38.4 square kilometers, including the following steps: first, determine that the map display range is 51.2*38.4 square kilometers, and the screen resolution is 320*240. Therefore, according to this resolution, the map level is selected as level 1, level 1=320*240*4=38400B, each pixel represents 160*n (n=1, 2, ...)m, and the entire screen display range is 51.2*38.4 square kilometers, and capture the map image of the area and store it in the storage space of the walkie-talkie terminal.

[0029] Then extract the map feature color from the map image stored in the storage space of the intercom terminal. Figure 2 In this embodiment, the specific process of extracting the map feature color step includes: S301. Determine the map zoom level according to the storage space size of the intercom; S302. In this embodiment, 7 color vectors C are generated by using RGB color components to represent 7 colors respectively. 1 (R C1 G C1 B C1 ), C 2 (R C2 G C2 B C2)…C 7 (R C7 G C7 B C7 ); S303. Traverse the pixel points of the map within the coverage area, represent the color of the current pixel point with RGB, and use the Euclidean distance formula to calculate the differences between the current pixel point and the map feature colors C 1 ~C 7 respectively. The smallest value indicates the closest color. Here, R, G, and B are the pixel point data of the current map, and R Ci , G Ci , B Ci are the pixel point data of the map feature color C i .

[0030] S304. Select a reasonable threshold D. When d < D, then this point belongs to the corresponding feature color.

[0031] After obtaining the feature color, dynamically convert the map picture into a 1-bit, 2-bit, or 3-bit color bitmap according to the extracted map feature color. Please refer to Figure 3 , and the specific conversion process is as follows: S401. After obtaining the feature color, divide the pixel points of the map picture into at most 7 groups, and the sum of the number of pixel points in each group is S 1 、S 2 …S 7 respectively. Calculate the proportion R of each group of pixel points in the pixel points of the entire picture, and calculate them as R 1 、R 2 …R 7 respectively. The calculation formula for the proportion of the pixel points is as follows: where R is the sum of the pixel points of the feature color, and Px is the picture pixel; S402. Select the threshold T of the number of color classification points in each group. When the pixel ratio of each group is R<T, it is considered that the characteristic color can be ignored. Select a reasonable threshold T, divide the characteristic colors of the target map into 2 groups, 4 groups, and 7 groups, respectively using 1 bit, 2 bits, and 3 bits, to achieve the ability to dynamically divide the map bit colors according to different map areas. Refer to the bitmap file format to generate 1-bit, 2-bit, and 3-bit bitmaps for the walkie-talkie to store the map. In this way, according to the previously calculated storage space of 5 320*240 pixel map images, the minimum storage space can be compressed to 12.5 / 4=3.12MB, and the maximum is only 12.5 / 4*3=9.36MB, which realizes a significant compression of the map storage space; 1-bit, 2-bit, and 3-bit bitmap storage formats, the values ​​of Bits Per Pixel at the offset address 001C of the bitmap file header are 1, 2, and 3 respectively; when displaying the map, the walkie-talkie restores it to 24-bit RGB true color for display according to the bitmap information, so as to achieve a reasonable display of the map.

[0032] The present invention optimizes the GIS map storage space through an algorithm without making any adjustments to the existing PDT digital trunking intercom hardware solution, thereby realizing the GIS function. When professionals perform tasks in the wild, suburbs and other areas where it is easy to get lost, they can use the GIS function of the intercom to realize practical functions such as navigation and linkage, and can realize the GIS function on the intercom without increasing the cost, thereby providing effective communication guarantee for professionals to perform tasks in the wild and suburbs, and improving the communication capabilities of search and rescue, navigation and linkage.

[0033] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A GIS implementation method based on PDT intercom, characterized in that: It includes the following steps: S1. Determine the map display range; S2. Select an appropriate range of map levels according to the display resolution of the walkie-talkie terminal, and intercept the map picture; S3. Extract the map feature colors from the intercepted map picture bitmap; S4. Dynamically convert the map picture into 1-bit, 2-bit, and 3-bit bitmaps according to the extracted map feature colors; S5. Compress the map picture and then download it into the walkie-talkie terminal for use as a GIS map; S6. The walkie-talkie terminal realizes map movement and zooming through changes in the positioning points.

2. A GIS implementation method based on PDT intercom according to claim 1, characterized in that: The specific content of the map level division in step S2 includes: Level 1 = 320 * 240 * 4 = 38400B, each pixel represents 160 * n (n = 1, 2,...) m, and the full-screen display range is 51.2 * 38.4 square kilometers; Level 2 = (320 * 2) * (240 * 2) * 4 = 153600B, each pixel represents 80 * n (n = 1, 2,...) m, and the full-screen display range is 25.6 * 19.2 square kilometers; Level 3 = (320 * 4) * (240 * 4) * 4 = 153600B, each pixel represents 40 * n (n = 1, 2,...) m, and the full-screen display range is 12.8 * 9.6 square kilometers; Level 4 = (320 * 8) * (240 * 8) * 4 = 614400B, each pixel represents 20 * n (n = 1, 2,...) m, and the full-screen display range is 6.4 * 4.8 square kilometers; Level 5 = (320 * 16) * (240 * 16) * 4 = 2457600B, each pixel represents 10 * n (n = 1, 2,...) m, and the full-screen display range is 3.2 * 2.4 square kilometers; where n represents the level of magnification and reduction of the planned map, and m is the unit of meter.

3. A GIS implementation method based on PDT intercom according to claim 1, characterized in that: The specific process of step S3 includes: S301. Determine the map zoom level according to the storage space size of the walkie-talkie terminal; S302. Generate i color vectors C1(R) using RGB color components to represent i colors respectively C1 G C1 B C1 )、C2(R C2 G C2 B C2 )…C i (R Ci G Ci B Ci ); S303. Traverse the pixel points of the map within the coverage area, use RGB to represent the color of the current pixel point, and use the Euclidean distance formula to calculate the distance between the current pixel point and the map feature colors C1 to C i The difference d, the smallest value means the color is closest; S304. Select a reasonable threshold D. When d < D, then this point belongs to the corresponding feature color.

4. The GIS implementation method based on PDT intercom according to claim 1 is characterized in that: The specific content of step S4 includes: S401. After obtaining the characteristic color, the pixels of the map image are divided into at most i groups, and the sum of the number of pixels in each group is S1, S2, ..., S i , calculate the proportion R of each group of pixels in the entire image, which are calculated as R1, R2…R i , The calculation formula for the proportion of the pixel points is as follows: where R is the sum of the pixel points of the feature color, and Px is the picture pixel; S402. Select a threshold T for the number of color classification points in each group. When the proportion of pixel points R in each group < T, it is considered that this feature color can be ignored. Select a reasonable threshold T to divide the feature colors of the target map into 2 groups, 4 groups, and 7 groups, using 1 bit, 2 bits, and 3 bits respectively, to achieve the ability to dynamically divide the map bit color according to different map areas.

5. The GIS implementation method based on PDT intercom according to claim 1 is characterized in that: The specific content of step S5 includes: Refer to the bitmap file format to generate 1-bit, 2-bit, and 3-bit bitmaps for the walkie-talkie to store the map. Compress the map picture according to the selected map level, and the compression range is 3.12MB - 9.36MB to achieve a large reduction in the map storage space, and then download the compressed map into the walkie-talkie terminal.

6. A GIS implementation method based on PDT intercom according to claim 3, characterized in that: The calculation formula of the Euclidean distance formula is: Among them, R, G, and B are the pixel data of the current map. Ci , G Ci , B Ci C is the map feature color i Pixel data.

7. A GIS implementation method based on PDT intercom according to claim 5, characterized in that: The storage formats of the 1-bit, 2-bit, and 3-bit bitmaps are such that the values ​​of Bits Per Pixel at the offset address 001C in the bitmap file header are 1, 2, and 3, respectively.

8. A GIS implementation method based on PDT intercom according to claim 1, 3 or 5, characterized in that: The resolution of the intercom terminal is 320*240, and the storage size of the GIS map is ≤12.5MB.

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