JP5100964B2 - Image generation method for viewing laser data in aerial laser surveying - Google Patents

Description

The present invention relates to a method for generating an image for browsing laser data in aviation laser surveying.

As an aerial laser surveying that measures the distance from the ground surface by irradiating a laser from the air toward the ground surface, the one described in Patent Document 1 is known. In this conventional example, data acquired by a laser sensor on an aircraft is stored in a data recording unit mounted on the aircraft, and is processed and analyzed by a ground data processing device after the measurement is completed.
JP 2003-156330 A

  However, in the above-described conventional example, since it takes time to analyze the observation data acquired on the flying object, there is a limit to use in the case where quick response is required, for example, at the time of disaster.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and provides an image generation method for viewing laser data in aeronautical laser surveying, which enables early confirmation of survey results and can meet the demand for quick response. For the purpose of provision.

Another object of the present invention, airborne laser scanning method that allows for confirmation of early survey results is to provide a contact and browsing laser data generating device.

  The return pulse data in the aerial laser surveying is a value corresponding to the distance between the laser scanner 2 and the ground surface. In order to obtain the surface roughness information of the ground surface or the features from these, the laser scanner 2 (aircraft at the time of surveying) is obtained. Information on the position and orientation of 1) and the emission angle of the laser pulse from the laser scanner 2 is required. As a result, the return pulse data is considered to be meaningful only under conditions where the positioning elements such as the position information of the air vehicle 1 can be determined, and the analysis of the observation data is performed from the stage when all the observation data are collected. As a matter of course, it has been assumed that it has been started, and this has caused a reduction in responsiveness due to the enormous amount of return pulse data, the enormous amount of processing calculations, and the like.

  On the other hand, the vehicle 1 being surveyed flies substantially horizontally and straightly, and the return pulse data is a point data group having a sufficient density, and further, an analytical approach that is generally performed, that is, In grasping survey results by detailed analysis based on accurate position information for each point, focusing on the fact that the final product is provided as a 3D or 2D image, the survey results can be processed through the processing procedure. Therefore, it is considered that quick response can be achieved by outputting the image information as a simplified image.

The present invention has been made based on the above findings,
The height information of each measurement point based on the return pulse data acquired by irradiating the laser pulse on the surface of the flying object 1 by irradiating the laser pulse at a predetermined angle in a direction substantially orthogonal to the flight direction toward the ground surface. An image generation method for viewing laser data in an aviation laser surveying that generates dot matrix data 4 assigned to brightness or the like,
From each data row in the main scanning direction in the return pulse data group in which the footprint acquired by the laser scanner 2 forms a zigzag shape, the position reference data 3 whose scanning angle at the time of data acquisition substantially coincides with a preset value is obtained. The steps to choose,
A procedure for generating dot matrix data 4 by arranging the data row in the sub-scanning direction in the data acquisition order so that the position reference data 3 are aligned on a straight line;
This is configured as a method for generating an image for browsing laser data in aeronautical laser surveying.
For further reference, according to the present invention,
A main scanning direction data string in which data in units of the main scanning direction at the time of acquisition of the return pulse data group acquired by irradiating the ground surface with a laser scanner on the flying object is arranged at a predetermined pitch in the order of acquisition is subordinate to a predetermined number of rows in the data acquisition order. Arranged at a predetermined pitch in the scanning direction,
Position reference data in which the scanning angle at the time of data acquisition defined in each main scanning direction data row substantially coincides with a preset value is aligned in the sub-scanning direction,
It is also possible to provide a laser data structure for browsing in aviation laser surveying in which flag data indicating data loss is embedded in data blank cells in the matrix.

  The return pulse data footprint 9 has a zigzag shape, for example, as shown in the uppermost part of FIGS. 6A and 6B, and the interval between adjacent data in the main scanning direction and the sub-scanning direction is indefinite. However, in consideration of the high data density characteristic of return pulse data and the fact that the yaw angle of the aircraft 1 during surveying is substantially constant, the return pulse data string in the main scanning direction has the same dot pitch. Even if it arrange | positions in order of appearance by (p), the quality as an image is not greatly inferior. Further, the processing arranged in a predetermined column in the order of appearance greatly reduces the processing amount as compared with the processing for calculating an accurate position on the footprint 9, so that the processing on the flying object 1 is also possible. .

  Furthermore, the process of arranging these main scanning direction data strings in the order of appearance in the sub-scanning direction at a predetermined dot pitch (p) is also effective for reducing the processing amount, and the flight of the flying object 1 during the surveying. Since the speed and pitch angle are considered to be generally horizontal and constant, the degradation of image quality due to this processing can be minimized.

  In addition, the position reference data 3 specified in each main scanning direction data string is data in which the scanning angle (θ) substantially matches a preset value. Since the flying object 1 is considered to fly at a constant roll angle (for example, a posture in which both wings of the aircraft are kept horizontal) during surveying, the distance from the flying object 1 with respect to the flight direction indicates a constant point on the ground surface. be able to. Accordingly, the dot matrix data 4 in which the main scanning direction data string is arranged so that the position reference data 3 is in a straight line has, for example, the flight direction and the scanning angle as the vertical axis and the horizontal axis, respectively, and the height information as the gradation value. Can be considered as image data. Further, since the selection of the position reference data 3 can be performed only by referring to the scanning angle data acquired along with the return pulse data, the processing amount is small and the processing on the machine is also possible.

  The scanning angle that serves as a reference for selection of the position reference data 3 can be determined as appropriate. However, since the change in the footprint position due to the change in the roll angle is the smallest in the position immediately below the flying object 1, the scanning angle is set to the position immediately below the flying object 1. The corresponding angle is desirable.

  The dot matrix data 4 obtained as described above can be displayed and viewed as an image by assigning luminance or the like to the gradation value. When visually evaluating an image, operations such as discriminating and removing unnatural discontinuous parts or abnormal points in the image, or connecting discontinuous parts can be performed very easily from the characteristics of the human eye. Therefore, it is possible to grasp the rough surface condition just by looking at this image.

  As a result, the survey result at the ground base station 5 can be judged early, and the situation of the disaster at the time of the disaster can be roughly grasped, or another survey or an additional survey area in the vicinity of the originally planned area can be instructed. Etc. becomes possible.

  Furthermore, since the dot matrix data 4 generally represents unevenness information on the ground surface, the proximity between adjacent dots is higher than that of a random data group. As a result, the compression efficiency of the dot matrix data 4 can be improved.

  Whether the lossless compression or the lossy compression is selected when compressing the dot matrix data 4 can be appropriately determined in consideration of the use of the image. When the image is used only for the purpose described above, the image quality is determined. Lossless compression can be used on the condition that there is no significant decrease. By adopting irreversible compression, the compression rate is increased and the transmission efficiency is improved.

  On the other hand, when the dot matrix data 4 is used not only for image display but also as a data group, it is desirable to employ lossless compression. When used as a data group, data for associating each data on the dot matrix with the scanning angle data is generated on the flying object 1, and together with GPS / IMU data, and data for orientation consisting of beam emission time data and scanning angle data It is transmitted to the ground base station 5. The ground base station 5 restores the dot matrix data 4 together with the evaluation as an image, and calculates the exact position of each point using GPS / IMU data or the like.

  In this way, by transmitting the dot matrix data 4 together with other orientation data to the ground base station 5 before the landing of the air vehicle 1, the calculation start time can be advanced.

  Various well-known compression algorithms for the dot matrix data 4 can be used and can be selected according to the purpose. However, when priority is given to compression efficiency, an algorithm for storing the difference between adjacent dots can be employed. The compression algorithm that uses the difference as the saved value generally uses the identifiable start dot value (return pulse data) as the saved value as it is, and then uses the difference value between the immediately preceding data and the data of interest as the saved value of the subsequent data. The routine is configured to be repeated until a predetermined condition, for example, the end of the column or a condition that the difference value exceeds a predetermined threshold is satisfied.

  As described above, the dot matrix data 4 has a feature that the closeness of values between adjacent dots is high, and therefore, by adopting a compression algorithm for storing this difference value. High compression ratio can be achieved.

  On the other hand, in order to give priority to versatility, it is desirable to employ a general-purpose still image compression algorithm. Some image compression algorithms employ transform coding by discrete cosine transform such as JPEG (Joint Photographic Experts Group), transform coding by wavelet transform such as JPEG2000, and other transform coding methods. Any of these can be used. When such a general-purpose algorithm is adopted, a special restoration program is not required when browsing the dot matrix data 4 as an image, so that versatility is improved. In addition, any lossy or lossless image compression algorithm can be used.

  In general, the light receiving unit of the laser scanner 2 can receive a plurality of reflected lights from the ground surface caused by the spread of the emitted pulse beam, and the time from the emission to the reception of the reflected waves is short. The return pulse corresponds to a reflected pulse at a higher altitude.

  The dot matrix data 4 can be generated for all orders of such an Nth order return pulse. For example, a plane in which only primary return pulses are collected, and a plane in which only secondary return pulses are collected. ,... Can be a set of planes in which only Nth order return pulses are collected.

  The highest order of the return pulse to be acquired varies depending on the characteristics of the survey target such as topography, and the highest order preset as the rating of the laser scanner 2 is not necessarily acquired. For this reason, data loss (dot drop) may occur in the plane after the secondary return pulse. However, by inserting flag data indicating dot drop for the dot, Correspondence can be simplified.

  On the other hand, for example, in forests and the like, the primary return pulse corresponds to the reflected pulse from the crown, and the highest return pulse is considered to correspond to the reflected pulse from the ground surface. It is also possible to select the dot matrix data 4 generation by the return order, such as only the return pulse or only the highest order return pulse.

  In this case, only the browsing-limited image can be irreversibly compressed as a return order designation plane, and can be added to the reversibly compressed plane for each order.

  In the above description, the present invention is described on the assumption that the dot matrix data 4 is generated and compressed on the air vehicle 1 and sent to the ground base station 5 and then viewed or grounded by the ground base station 5. However, the dot matrix data 4 according to the present invention can be generated on the ground base station 5 side on the basis of the scanning angle data transmitted together with the return pulse data compressed by an appropriate means on the aircraft 1. It is. Even if comprised in this way, prior to or at the same time as the orientation calculation, it is possible to view the survey results and to evaluate them, thereby improving responsiveness.

  According to the present invention, since the survey result can be confirmed at an early stage, the demand for quick response can be met.

  FIG. 1 shows an outline of aircraft laser survey using an aircraft 1 such as an aircraft or helicopter. In the figure, reference numeral 10 denotes a laser measurement unit mounted on the flying object 1, and includes a laser scanner 2, a reflected wave reception sensor 11, and a GPS / IMU (Global Positioning System / Internal Measurement Unit) (12). The laser scanner 2 includes a laser emitting unit 2a that emits a laser pulse at predetermined time intervals by a control unit (not shown), and a rotating mirror 2b that oscillates the laser pulse at a predetermined angle to form a scan beam. Is reflected by the reflected wave receiving sensor 11 as a return pulse.

  As shown in FIG. 1B, the return pulse is composed of a plurality of reflected pulses (usually about 1 to 5 times) by the feature for one emitted laser pulse. Return pulse capture time information for the irradiation pulse is output as return pulse data (Pkn) (in this specification, the subscript “k” indicates the reflection pulse reflection order, and the subscript “n” indicates the laser pulse emission order). The The GPS / IMU (12) outputs the GPS position, inclination value, etc. of the flying object 1 at predetermined time intervals.

  In addition to the return pulse data (Pkn) and GPS / IMU information, the laser pulse emission time data (Tn) and the mirror rotation angle data of the rotating mirror 2b at that time, that is, the scanning angle data (θn) are collected as observation data. Transmitted to the terrestrial base station 5 from the subsequent transmission unit 20 (hereinafter, observation data excluding GPS / IMU data is collectively referred to as “laser data”, and observation data excluding return pulse data is referred to as “ Collectively referred to as “data for orientation”). As will be described later, the ground base station 5 calculates the distance between the flying object 1 and the ground surface by applying the orientation data to the return pulse data (Pkn) (hereinafter referred to as “orientation computation”), and the position of the ground surface. Calculate the height. As shown in FIG. 1B, the scanning angle data (θn) is indicated by the sign bit attached to the data value corresponding to the rotation angle, with the rocking center of the rotating mirror 2b as o.

  The return pulse data (Pkn), the laser pulse emission time data (Tn), the GPS position, and the IMU inclination information are output as numerical values appropriately dimensionless by the structure of the laser measurement unit 10. Further, the time information such as the laser pulse emission time or the return pulse data may be, for example, the elapsed time from the start of measurement.

  FIG. 2 shows a flowchart of the aerial survey method, and FIG. 3 shows details of the laser measurement unit 10 and the transmission unit 20 mounted on the aircraft 1 used for the aerial survey method. As described above, the laser measurement unit 10 includes the laser scanner 2, the reflected wave reception sensor 11, and the GPS / IMU (12), and observation values in the laser scanner 2 and the reflected wave reception sensor 11 are stored in the pulse data generation unit 13. Observation values in the GPS / IMU (12) are output to the GPS / IMU data generation unit 14, respectively.

  The output format in the pulse data generation unit 13 is shown in the upper part of FIG. 4A, and the output format in the GPS / IMU data generation unit 14 is shown in FIG. 4B. First, as described above, the pulse data generation unit 13 outputs a data string in which output values corresponding to the emission pulse are arranged in a predetermined order with the emission pulse as a unit. The illustrated example shows a data format when it is assumed that return pulse data (Pkn) up to the fifth order is acquired for each emitted laser pulse, and laser pulse emission time data (Tn) in order from the head. ), Scanning angle data (θn), and return pulse data (Pkn) are stored.

  Further, as described above, since the return pulse data (Pkn) is not necessarily acquired up to the fifth order, for example, “0” is assigned to the storage position of the order that could not be acquired.

  On the other hand, from the GPS / IMU data generation unit 14, as shown in FIG. 4B, GPS measurement time (TAm), IMU measurement time (TBm), x-direction acceleration (VXm), x-direction angle (AXm), The y-direction acceleration (VYm), the y-direction angle (AYm), the z-direction acceleration (VZm), and the z-direction angle (AZm) are output (the subscript “m” indicates the data acquisition order). The observed value in the GPS / IMU (12) corresponding to the return pulse data (Pkn) is interpolated based on the GPS measurement time (TAm) or IMU measurement time (TBm) with respect to the laser pulse emission time data (Tn). Is obtained by

  Therefore, in this embodiment, when laser surveying by the air vehicle 1 is started, observation data in the laser measuring unit 10 is output to the pulse data generating unit 13 or the GPS / IMU data generating unit 14 to be predetermined. A data string is generated (FIG. 2; step S1), and then the compression processing in the compression processing unit 15 is performed on the laser data (FIG. 2; step S2).

  In this embodiment, GPS / IMU data having a smaller amount of data than laser data is directly transmitted without performing a compression operation, so that the direct encoding processing unit 16 does not pass through the compression processing unit 15. The file is combined with the compressed image with respect to the pulse data, but may be output to the encoding processing unit 16 after performing a compression operation as necessary.

  The compression processing unit 15 includes a data separation unit 15a, an image conversion unit 15b, and a compression unit 15c. First, data separation processing in the data separation unit 15a is performed on the laser data (FIG. 2; Step S2-1). In the data separation unit 15a, as shown in FIG. 4A, the output laser data is separated into three types of laser pulse emission time data (Tn), scanning angle data (θn), and return pulse data (Pkn). It is divided into data strings (SD (T), SD (θ), SD (P)). As shown in FIG. 4A, the separated data strings SD (T) and SD (θ) based on the laser pulse emission time data (Tn) and the scanning angle data (θn) are arranged in the order of pulse emission, and return pulse data ( Pkn) has a format in which a group of five data arranged in the order of reflection order is arranged in the order of pulse emission. Further, in the separated data string SD (P) of the return pulse data (Pkn), a data end mark is inserted at the boundary of the data group as necessary.

  When the processing in the data separation unit 15a is completed, the separation data string SD (P) of the return pulse data (Pkn) is output to the image conversion unit 15b configured as a return pulse data viewing laser data generation device, and the other separation is performed. The data strings SD (T) and SD (θ) are output to the compression unit 15c.

  The image conversion unit 15 b includes a position reference data search unit 7, a data string generation unit 6, and a dot matrix data generation unit 8. First, the position reference data search unit 7 searches the position reference data 3 in units of main scanning lines (FIG. 2; step S2-2). The position reference data 3 is return pulse data when the scanning angle is close to a predetermined angle (in this embodiment, “0” corresponding to immediately below the aircraft 1), and the position reference data search unit 7 is described later. The column position in each row of the data column array to be output is output.

  In searching for the position reference data 3, as shown in FIG. 5A, the position reference data search unit 7 scans the scan rate (the number of main scanning lines per second) and the pulse rate (the number of fired pulses per second). To obtain the number (Lp) of fired pulses per main scanning line (Ls). Next, the number of firing pulses (Lp) is set to the number of elements [D] in one row, and a scanning angle array (θC [L] [D]) having the number of rows [L] corresponding to the number of main scanning lines is generated. After storing the scanning angle data (θn) in each cell, an element having a scanning angle near “0” is searched for each row of the two-dimensional scanning angle array (θC [L] [D]). Store in θC [L] [0] and terminate the process.

  By the above operation, on the zigzag footprint 9 shown in the uppermost stage of FIG. 6, the data string corresponding to the one end of the rotation of the rotating mirror 2b to the other end of the swing, that is, the data string unit in the main scanning direction. The position reference data 3 can be specified simply by referring to θC [L] [0]. In FIG. 6, the position reference data 3 is indicated by a black circle.

  The data string generation unit 6 decomposes the return pulse data (Pkn) into a data string in the main scanning direction (FIG. 2; step S2-3). Specifically, as shown in FIG. 5B, the data pulse array A (P) in which the number of fired pulses (Lp) is the number of elements in one row and the number of main scanning lines is the number of rows is the acquired pulse order. In this embodiment, five pieces are generated. Thereafter, the separated data string SD (P) of the return pulse data (Pkn) is sequentially stored in the cells of the data string array A (P) selected by the return order, and after reaching the end of the row, the data A new row is added to the column array A (P), and the same processing is repeated until the end of the file of the separated data column SD (P) is reached.

  With the above operation, as shown in FIG. 6, the measurement points on the footprint 9 having various data intervals and zigzag are arranged in the sub-scanning direction at a predetermined dot pitch (P) for each data row unit in the main scanning direction. The obtained matrix data is obtained.

  The dot matrix data generation unit 8 shifts the element position indicated by θC [L] [0] to a predetermined column position for each row of the data column array A (P). When the number of columns of the data string array A (P) is insufficient at the time of shifting, a new column is inserted at the shift side column end of the data string array A (P). Further, the dot matrix data generation unit 8 inserts a no-data flag into the array element that has become blank as a result of the shift, and the dot matrix data 4 is completed (FIG. 2; step S2-4). The dot matrix data 4 is shown at the bottom of FIG. In the figure, the no-data flag is indicated by a broken-line circle.

  The compression unit 15c performs compression to the dot matrix data 4 and compression of the separated data string SD (T) based on other laser data, that is, scanning angle data (θn) and laser pulse emission time data (Tn). (FIG. 2; step S2-5).

  As a compression format for the dot matrix data 4, a general-purpose image compression format (for example, a lossy compression format using JPEG, a lossless compression format) is used.

  On the other hand, the laser pulse emission time data (Tn) or the scanning angle data (θn) is compressed using a known lossless compression algorithm.

  When the compression processing for each separated data string (SD) is completed as described above, the combination processing is performed and the files are combined into one file, and then the encoding processing unit 16 performs encoding (FIG. 2; step S3). ). Entropy encoding or the like can be used for the encoding process.

  When the encoding process is completed, first, the streaming process is performed in the streaming unit 17 in order to enable analysis in the terrestrial base station 5 during data transmission, and then the carrier wave is shaped in the transmission data conversion process unit 18. Are transmitted from the output unit 19 (FIG. 2; step S4).

  In the above embodiment, when only pulse data is compressed and GPS / IMU data is configured to transmit GPS / IMU data directly using the time of turning and moving to the measurement route. However, it is also possible to transmit the GPS / IMU data after compression processing.

  FIG. 7 shows a block diagram of the ground base station 5 that receives transmission information from the aircraft 1. The terrestrial base station 5 includes a data reproduction unit 32 including a reception processing unit 30 and a restoration processing unit 31. When the reception unit 30a of the reception processing unit 30 receives the compressed data from the flying object 1 (FIG. 2; step S5), the streaming processing unit 30b performs the streaming process so that subsequent data analysis can be performed while receiving the compressed data. And output to the decoding unit 31a of the restoration processing unit 31 (FIG. 2; step S6). In the decoding unit 31a, the encoding and combination of the compressed data file are canceled to return to the state before the encoding, and further, the restoring unit 31b performs the restoring process (FIG. 2; step S7). Utilizing the fact that the decoded dot matrix data 4 is image data, an image is displayed on the browsing unit 33 formed by a general-purpose browser (FIG. 2; step S8).

  On the other hand, in the decompression process, the processes in the compression processing unit 15 are executed in the reverse order. For example, for the dot matrix data 4, first, after deleting the no-data flag attributed to dot shift and restoring the data array, separation is performed based on the number of firing pulses per main scanning line (Lp). The data string SD (P) is restored. Similarly, after the separation data strings SD (θ) and SD (T) of the firing time data (Tn) and mirror rotation angle data (θn) are restored, these are combined in the data combining unit 31c (FIG. 2; step). S9), the output from the pulse data generator 13 is reproduced.

  The combined data is analyzed by the data analysis unit 34, and the measurement result by the return pulse group is calculated (FIG. 2; step S10). In the analysis, the observation data is temporarily stored in the pulse data / GPS / IMU data storage unit 34a, and the actual position and the like are calculated in the actual distance / coordinate processing unit 34b. The actual distance / coordinate processing unit 34b uses the internal rating element based on the characteristics of the optical system mounted on the flying object 1 and the external rating element based on the GPS / IMU data to determine a predetermined return pulse footprint 9. Calculate the position and height in the projection space.

  Since each point data obtained in this way has three-dimensional information, it is also possible to display the ground surface on the pointillism using this. The point data is stored in the point data storage unit 35 and used for these purposes.

  Furthermore, in this embodiment, the ground base station 5 is provided with a 3D processing unit 36. The 3D processing unit 36 includes a 3D data generation unit 36a for forming a 3D image including, for example, a three-dimensional polygon and a texture based on the point data group. The data generated by the 3D data generation unit 36a is inserted into the generation 3D data storage unit 36b and displayed on the 3D data display unit 37 as desired.

  In addition, the ground base station 5 includes a comparison unit 38 so that information such as crustal movements and disasters can be obtained immediately. The comparison unit 38 includes an existing 3D data storage unit 38a, a difference data generation unit 38b, and the 3D data display unit 37. The output from the 3D data generation unit 36a is compared with the existing 3D data in the difference data generation unit 38b, and a difference on the image is detected. The detection result is displayed on the 3D data display unit 37, and it is possible to instruct re-measurement or expansion of the measurement range to the flying aircraft 1 as necessary.

  In the above, the data reproduction unit 32, the data analysis unit 34, the 3D processing unit 36, and the comparison unit 38 can also be achieved by a computer program that causes a computer to operate so as to exhibit the function.

  In the above description, the return pulse data of all orders is converted into a dot matrix and reversibly compressed. However, a return pulse of a specific return order, for example, only the primary return pulse or only the highest return pulse is extracted. It is also possible to form a dot matrix, compress it, and transmit it to the ground base station 5.

  In this case, the dot matrix data 4 is handled as browsing-only data, and return pulse data that is reversibly compressed by an appropriate algorithm is used for the orientation calculation.

  FIG. 8 shows another embodiment of the aircraft laser surveying method. In the description of this embodiment, the same processing as that of the above-described embodiment is denoted by the same step number in the drawing and description thereof is omitted. In this embodiment, the laser data is reversibly compressed on the aircraft 1 using an appropriate compression algorithm, and transmitted to the ground base station 5 together with the GPS / IMU data. In response to this, the ground base station 5 performs necessary decoding processing, restores the compressed file, and then generates dot matrix data 4 that is browsing laser data. The dot matrix data 4 is browsed by the browsing unit 33 using an appropriate image browser.

It is a figure which shows this invention, (a) is explanatory drawing which shows a laser measurement, (b) is explanatory drawing which shows a return pulse. It is a flowchart of an aerial laser surveying method. It is a block diagram which shows the flying body mounting part of a laser measurement system. FIG. 5 is a diagram showing a data format in the data generation unit, where (a) shows an output from the pulse data generation unit and an operation of the data separation unit, and (b) shows an output from the GPS / IMU data generation unit. It is. 4A and 4B are explanatory diagrams showing the operation of the image conversion unit, in which FIG. 4A is a time-rotation angle diagram of a rotating mirror, and FIG. It is explanatory drawing which shows operation | movement of an image conversion part, (a) is a general view which shows the process with respect to a return pulse, (b) is an enlarged view of (a). It is a block diagram which shows the structure by the side of the ground reference station of a laser measurement system. It is a flowchart which shows other embodiment of the aviation laser surveying method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aircraft 2 Laser scanner 3 Position reference data 4 Dot matrix data 5 Ground base station 6 Data sequence generation part 7 Position reference data search part 8 Dot matrix data generation part

Claims (10)

The height information of each measurement point based on the return pulse data obtained by irradiating the laser pulse on the surface of the flying object at a predetermined angle in a direction substantially perpendicular to the flight direction toward the ground An image generation method for viewing laser data in an aviation laser surveying that generates dot matrix data assigned to
Position reference data whose scanning angle at the time of data acquisition substantially matches a preset value is selected from each data row in the main scanning direction in the return pulse data group in which the footprint acquired by the laser scanner has a zigzag shape. Procedure and
A procedure for generating dot matrix data by arranging the data row in the sub-scanning direction in order of data acquisition so that the position reference data is aligned on a straight line;
A method for generating an image for browsing laser data in aerial laser surveying. The laser scanner receives a plurality of return pulses from the ground surface caused by the spread of a single emitted laser pulse,
And selects a predetermined number-th return pulse data of the plurality of times from the return pulse data group, for viewing of the laser data in airborne laser scanning according to claim 1 further comprising a procedure for the dot matrix data generation target Image generation method. The image for browsing the laser data generated by the method according to claim 1 or 2 on the flying object is compressed by an image compression algorithm and transmitted to the ground base station,
Laser data browsing method in aviation laser surveying that displays dot matrix data as images at ground base stations. A flying object for calculating an image of the surface of a ground or a feature from a return pulse data by compressing a browsing image of laser data generated by the method according to claim 1 or 2 on a flying object by a reversible compression algorithm. Along with the orientation data such as the location of the
An aerial laser surveying method that performs orientation calculation to obtain unevenness information of the ground surface or features from the return pulse data obtained by restoring the compressed file at the ground base station. The height information of each measurement point based on the return pulse data obtained by irradiating the laser pulse on the surface of the flying object at a predetermined angle in a direction substantially perpendicular to the flight direction toward the ground An image generation device for viewing laser data in aeronautical laser surveying that generates dot matrix data assigned to
A data string generation unit that separates a return pulse data group in which a footprint acquired by the laser scanner has a zigzag shape into main scanning direction data strings;
A position reference data search unit for searching for position reference data whose scanning angle at the time of data acquisition substantially matches a preset value from within each main scanning direction data string;
A dot matrix data generation unit that generates dot matrix data in which the main scanning direction data string is arranged in the sub-scanning direction in order of acquisition of a predetermined number of rows so that the position reference data is located on the same straight line;
An image generation apparatus for browsing laser data in aeronautical laser surveying. The laser scanner receives a plurality of return pulses from the ground surface caused by the spread of a single emitted laser pulse,
And to select the previous SL predetermined number-th return pulse data of the plurality of times from the return pulse data group, viewing the laser data in airborne laser scanning according to claim 5, further comprising a procedure for the dot matrix data generation target Image generation device. A laser data browsing image generated by the laser data browsing image generating device according to claim 5 or 6 on the flying object is compressed by an image compression algorithm and transmitted to the ground base station,
Display image of dot matrix data at ground base station
Laser data browsing system characterized by that. The laser data viewing image generated by the laser data viewing image generating device according to claim 5 or 6 on the flying object is compressed by a reversible compression algorithm, and the unevenness information of the ground surface or the feature is obtained from the return pulse data. Is transmitted to the ground base station together with the orientation data such as the position of the aircraft to calculate
Performs an orientation calculation to obtain unevenness information of the ground surface or features from the return pulse data obtained by decompressing the compressed file at the ground base station.
  An aerial laser surveying system characterized by that. The height information of each measurement point based on the return pulse data obtained by irradiating the laser pulse on the surface of the flying object at a predetermined angle in a direction substantially perpendicular to the flight direction toward the ground An image generation program for viewing laser data in aviation laser surveying to generate dot matrix data assigned to
From each data row in the main scanning direction in the return pulse data group in which the footprint acquired by the laser scanner has a zigzag shape, data whose scanning angle at the time of data acquisition substantially coincides with a preset value is used as position reference data. The steps to choose,
  A procedure for generating dot matrix data by arranging the data row in the sub-scanning direction in the data acquisition order so that the position reference data is aligned on a straight line;
  An image generation program for browsing laser data for causing a computer to execute the above. The laser scanner receives a plurality of return pulses from the ground surface caused by the spread of a single emitted laser pulse,
And a procedure for selecting a predetermined number of return pulse data among the plurality of times from the return pulse data group,
A procedure for setting the predetermined number of return pulse data as a dot matrix data generation target;
An image generation program for browsing laser data according to claim 9 for causing a computer to execute.

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