Digital core three-dimensional real scene modeling method based on close-range photogrammetry technology

Abstract

The application discloses a kind of digital core three-dimensional real scene modeling methods based on close-range photogrammetry technology.Measuring the length and radius of core section;Set the control point coordinates of core section;According to fixed camera shooting point, the entity of core section is forwardly shot, and the core image data of a certain camera shooting point is obtained;Along the horizontal central axis surface of core section, a circle of core section is completed n evenly distributed camera shooting point shooting, and the core image data of a circle of n camera shooting point is obtained;Along the horizontal central axis surface of core section, vertically upward and downward translation as shooting plane, evenly shoot around core section along the shooting plane, complete the camera multi-point shooting of the mth plane, and obtain the core image data of the mth circle;The core image data and control point coordinates corresponding to multiple core sections are respectively introduced into software, three-dimensional real scene modeling is carried out, and the whole model of core is spliced.The application effectively solves the storage problem of physical core, and improves the service life of core.

Description

Technical Field

[0001] This invention belongs to the field of geological exploration technology, specifically relating to a method for digital core 3D real-scene modeling based on close-range photogrammetry. Background Technology

[0002] Cores are cylindrical rock samples extracted from boreholes using ring drill bits and other coring tools to meet the needs of geological exploration and engineering projects. Currently, cores are typically stored as physical objects or in two-dimensional image formats.

[0003] In geological exploration work such as large-scale hydropower projects and engineering survey projects, a large number of rock cores are accumulated. Physical storage, as the main method of preserving borehole sampling data, is a direct reflection of underground rock strata and has advantages such as being intuitive and accurate. However, physical rock cores present great inconveniences in terms of transportation, storage, and management, and it is impossible to maintain their original state and integrity for a long time. On the one hand, due to changes in natural conditions and human factors, rock cores gradually lose their original appearance after being taken to the surface. On the other hand, during the transportation of rock cores, repeated handling may cause damage and displacement, especially for rock cores from important strata, which may become incomplete due to repeated sampling. Once a rock core is damaged, it will be lost forever, which will cause irreparable losses for large-scale hydropower projects.

[0004] Current core digital information acquisition technologies mainly include surface image digitization, spectral scanning, X-ray fluorescence elemental testing, multi-scale CT scanning, micro-area scanning electron microscopy imaging, physical property parameter measurement, and nuclear magnetic resonance, etc. Most of them are two-dimensional image storage modes, which are costly and inconvenient to operate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a digital core 3D real-scene modeling method based on close-range photogrammetry.

[0006] The technical solution adopted in this invention is: a digital core 3D real-scene modeling method based on close-range photogrammetry, comprising:

[0007] Step 1: Measure the length and radius of the core segment;

[0008] Step 2: Set a reference coordinate system and obtain the coordinates of the control points of the core segment based on this coordinate system;

[0009] Step 3: Take a frontal shot of the core segment at a fixed camera shooting point to obtain core image data at a certain camera shooting point;

[0010] Step 4: Along the horizontal central plane m0 of the core segment, complete the shooting at n uniform camera shooting points around the core segment to obtain core image data at n camera shooting points in one circle;

[0011] Step 5: Move vertically upwards and downwards uniformly along the horizontal central axis plane m0 of the core segment to serve as the shooting plane. Take pictures uniformly around the core segment along this shooting plane to complete the multi-point shooting of the m-th plane and obtain the core image data of the m-th ring.

[0012] Step 6: Import the core image data and control point coordinates corresponding to multiple core segments into the software to perform 3D real-scene modeling and obtain 3D real-scene models of multiple core segments;

[0013] Step 7: Piece together the 3D real-world models of multiple core segments into a complete core model.

[0014] Step 1 above specifically includes: measuring the length L1 and radius R of the first core segment, the length L2 and radius R of the second core segment, ... the length Lk and radius R of the kth core segment, where k is an integer.

[0015] Step 2 above specifically includes: setting the coordinates of the top center of the first core segment to P0(0,0,0), constructing a reference coordinate system, setting the XYZ coordinate axes, with the Z-axis pointing to the vertical axis of the core segment, the X-axis to the horizontal axis of the bottom surface of the core segment, and the Y-axis to the axis perpendicular to the X and Z axes of the bottom surface of the core segment. Based on the length L1 and radius R of the first core segment, obtain the position coordinates of two points on the bottom surface of the first core segment: P1(-R,0,-L1) and P2(R,0,-L1). The line connecting the two points P1 and P2 passes through the center of the bottom surface of the first core segment. Then, P0, P1, ... The coordinates of the three points P2 are used as the control points for the first core segment. The coordinates of the center of the top surface of the second core segment are P3 (0,0,-L1). Based on the length L2 and radius R of the second core segment, the position coordinates of two points on the bottom surface of the second core segment are obtained: P4 [-R,0,-(L1+L2)] and P5 [R,0,-(L1+L2)]. The line connecting the two points P4 and P5 passes through the center of the bottom surface of the second core segment. The coordinates of P3, P4, and P5 are used as the control points for the second core segment. This process is repeated until the kth core segment.

[0016] Step 6 above specifically includes: importing the core image data corresponding to the first core segment and the coordinates of the three control points P0, P1, and P2 into the software to perform 3D real-scene modeling and obtain the 3D real-scene model of the first core segment; importing the core image data corresponding to the second core segment and the coordinates of the three control points P3, P4, and P5 into the software to perform 3D real-scene modeling and obtain the 3D real-scene model of the second core segment; taking the next core segment, and so on, to obtain the 3D real-scene model of the kth core segment.

[0017] The overlap between adjacent photos in the same circle is no less than 70%.

[0018] The angular separation between different camera shooting points on the same part of the core sample is less than 15 degrees.

[0019] In step 4 above, n camera shooting points are completed around the core segment, where n = 1, 2, ..., n ≥ 24.

[0020] In step 5 above, multiple camera shooting points are taken around the core segment m times, where m ≥ 3.

[0021] The core images and coordinates of the three control points corresponding to each core segment were imported into ContextCapture software to perform 3D real-world modeling of the core.

[0022] Since core sampling is generally carried out in multiple rounds during drilling, the core may be divided into several segments due to poor core quality, well-developed structural surfaces, external factors such as twisting and friction between structural surfaces or the rock mass, etc., during the same round of core sampling. Therefore, the real-world models of the segmented core need to be spliced ​​together during the 3D real-world modeling process.

[0023] This invention represents the first application of 3D real-scene modeling technology to 3D core modeling.

[0024] This invention utilizes close-range photogrammetry and real-scene modeling technology, and incorporates three-dimensional real-scene modeling technology into core digital modeling to construct a high-precision three-dimensional individual core model.

[0025] This invention reflects the true texture and geometric shape of the rock core, forming a 1:1 high-precision digital model of the rock core.

[0026] This invention effectively solves the problems of difficulty in transporting, storing, managing and utilizing physical rock cores, and preserves the three-dimensional digital model information of rock cores for a long time, thereby improving the preservation life of rock cores.

[0027] This invention is particularly advantageous in large and medium-sized projects. Due to the long construction period, tight schedule, and fast exploration speed in large-scale engineering projects, as well as the large number of rock cores and the difficulty in management, this invention can significantly improve the management and digitization level of rock cores in water conservancy and hydropower projects. It can realize simultaneous exploration, collection, and real-scene modeling, which not only facilitates the permanent preservation of rock core archives, but also leaves valuable original geological exploration data for large-scale hydropower projects, thereby improving the digitization management level of rock core archives in large-scale exploration, pumped storage power station projects, hydropower projects, and other projects. Attached Figure Description

[0028] Figure 1 This is a flowchart of the present invention.

[0029] Figure 2 This is a schematic diagram of the locations where core samples were taken.

[0030] Figure 3 A schematic diagram showing the setting of the reference coordinate system and control points for the core section. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but these descriptions do not constitute a limitation on the present invention.

[0032] like Figure 1 As shown, the present invention includes the following steps:

[0033] Step 1: Measure the length L1 and radius R of the first core segment;

[0034] Step 2: Set the coordinates of the top center of the first core segment to P0(0,0,0), construct a reference coordinate system, and set the XYZ coordinate axes. The Z-axis points to the vertical axis of the core segment, the X-axis points to the horizontal axis of the bottom surface of the core segment, and the Y-axis points to the axis perpendicular to the X and Z axes of the bottom surface of the core segment. Based on the length L1 and radius R of the first core segment, obtain the position coordinates of two points on the bottom surface of the first core segment: P1(-R,0,-L1) and P2(R,0,-L1). The line connecting the two points P1 and P2 passes through the center of the bottom surface of the first core segment. Use the three coordinate points P0, P1, and P2 as control point coordinates.

[0035] Step 3: Take a frontal shot of the core segment at a fixed camera shooting point to obtain core image data at a certain camera shooting point;

[0036] Step 4: Along the horizontal central plane m0 of the core segment, complete the shooting at n uniform camera shooting points around the core segment to obtain core image data at n camera shooting points in one circle;

[0037] like Figure 2 As shown, step 5: Move vertically upward and downward uniformly along the horizontal central axis plane m0 of the core segment as the shooting plane, and take pictures uniformly around the core segment along the shooting plane to complete the multi-point shooting of the camera on the m-th plane and obtain the core image data of the m-th circle.

[0038] Step 6: Import the core image data corresponding to the first core segment and the coordinates of the three control points P0, P1, and P2 (in text file format) into the software. In the image association editor, select the image from the image list to which measurement points need to be added (select at least 3 photos for each control point), find the location of the control point, set the image association position, and then associate the coordinates of all control points with the images. Then perform 3D real scene modeling to obtain the 3D real scene model of the first core segment.

[0039] Step 7: Measure the length L2 and radius R of the second core segment. Then the coordinates of the center of the top surface of the second core segment are P3(0,0,-L1).

[0040] like Figure 3 As shown, step 8: Based on the length L2 and radius R of the second core segment, obtain the position coordinates of two points on the bottom surface of the second core segment: P4[-R,0,-(L1+L2)] and P5[R,0,-(L1+L2)]. The line connecting the two points P4 and P5 passes through the center of the bottom surface of the second core segment. Use the three coordinate points P3, P4, and P5 as control point coordinates.

[0041] Step 9: Repeat steps 3 to 5 to import the core image data corresponding to the second core segment and the coordinates of the three control points P3, P4, and P5 into the software. In the image association editor, select the image from the image list to which measurement points need to be added (select at least 3 photos for each control point), find the location of the control point, set the image association position, and so on to achieve the association of all control point coordinates with the images. Then, perform 3D real scene modeling to obtain the 3D real scene model of the second core segment.

[0042] Step 10: Take a core segment and repeat the process to obtain the 3D model of the kth core segment. Then, stitch the 3D models of the 1st, 2nd, 3rd...kth core segments together to form the overall core model (by directly loading the segmented coordinate model using software such as Geomagic Wrap or 3DMAX, and rotating the second core segment along the Z-axis according to the texture until it completely matches the texture of the first core segment... repeat the operation until the kth core segment).

[0043] The overlap between adjacent photos in the same circle is no less than 70%.

[0044] The angular separation between different camera shooting points on the same part of the core sample is less than 15 degrees.

[0045] In step 4 above, n camera shooting points are completed around the core segment, where n = 1, 2, ..., n ≥ 24.

[0046] In step 5 above, multiple camera shooting points are taken around the core segment m times, where m ≥ 3.

[0047] The core images and coordinates of the three control points corresponding to each core segment were imported into ContextCapture software to perform 3D real-world modeling of the core.

[0048] This invention utilizes photography and real-scene modeling to create a high-precision, individual, true 3D model of the rock core, reproducing the physical rock core at a 1:1 scale. This provides a novel technical solution for the storage and management of physical rock cores. It not only overcomes the realism issues of traditional 2D digitization technology, enabling interactive and true 3D management within a 3D environment, bringing the physical rock core data in archives to life, but also reduces interference from archival management work, thus facilitating the preservation and management of the rock cores. It is low-cost, easy to operate, extends the lifespan of rock cores, and improves the management and digitization levels of rock cores in hydropower projects.

[0049] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A method for digital core 3D real-scene modeling based on close-range photogrammetry, characterized in that: Includes the following steps: Step 1: Measure the length and radius of the core segments, specifically including: measuring the length L1 and radius R of the first core segment, the length L2 and radius R of the second core segment, ... the length Lk and radius R of the kth core segment, where k is an integer; Step 2: Establish a reference coordinate system and obtain the coordinates of the control points of the core segment based on this coordinate system. Specifically, this includes: setting the coordinates of the top center of the first core segment to P0(0,0,0), constructing a reference coordinate system, and setting the XYZ coordinate axes. The Z-axis points to the vertical axis of the core segment, the X-axis points to the horizontal axis of the bottom surface of the core segment, and the Y-axis points to the axis perpendicular to the X and Z axes on the bottom surface of the core segment. Based on the length L1 and radius R of the first core segment, obtain the position coordinates of two points on the bottom surface of the first core segment: P1(-R,0,-L1) and P2(R,0,-L1). The line connecting the two points P1 and P2 passes through the first core segment. The coordinates of the three points P0, P1, and P2 at the bottom center of the first core segment are used as the control points. The coordinates of the top center of the second core segment are P3(0,0,-L1). Based on the length L2 and radius R of the second core segment, the position coordinates of two points on the bottom surface of the second core segment are obtained: P4[-R,0,-(L1+L2)] and P5[R,0,-(L1+L2)]. The line connecting the two points P4 and P5 passes through the bottom center of the second core segment. The coordinates of P3, P4, and P5 are used as the control points of the second core segment. This process is repeated until the k-th core segment. Step 3: Take a frontal shot of the core segment at a fixed camera shooting point to obtain core image data at a certain camera shooting point; Step 4: Along the horizontal central plane m0 of the core segment, complete the shooting at n uniform camera shooting points around the core segment to obtain core image data at n camera shooting points in one circle; Step 5: Move vertically upwards and downwards uniformly along the horizontal central axis plane m0 of the core segment as the shooting plane, and take pictures uniformly around the core segment along this shooting plane to complete the multi-point shooting of the m-th plane and obtain the core image data of the m-th circle. Step 6: Import the core image data and control point coordinates corresponding to multiple core segments into the software to perform 3D real-scene modeling and obtain 3D real-scene models of multiple core segments. Specifically, this includes: importing the core image data and coordinates of three control points P0, P1, and P2 corresponding to the first core segment into the software to perform 3D real-scene modeling and obtain the 3D real-scene model of the first core segment; importing the core image data and coordinates of three control points P3, P4, and P5 corresponding to the second core segment into the software to perform 3D real-scene modeling and obtain the 3D real-scene model of the second core segment; then, taking the next core segment and so on, to obtain the 3D real-scene model of the kth core segment. Step 7: Piece together the 3D real-world models of multiple core segments into a complete core model. This includes: directly loading the segmented 3D real-world models with coordinates of each core segment into the software; rotating the 3D real-world model of the second core segment along the Z-axis according to the texture until it completely matches the texture of the 3D real-world model of the first core segment; repeating the above operation until the kth core segment is obtained, thus piecing together the complete core model.

2. The digital core 3D real-scene modeling method based on close-range photogrammetry technology according to claim 1, characterized in that: The overlap between adjacent photos in the same circle is no less than 70%.

3. The digital core 3D real-scene modeling method based on close-range photogrammetry technology according to claim 1, characterized in that: The angular separation between different camera shooting points on the same part of the core sample is less than 15 degrees.

4. The digital core 3D real-scene modeling method based on close-range photogrammetry technology according to claim 1, characterized in that: In step 4 above, n camera shooting points are completed around the core segment, where n = 1, 2, ..., n ≥ 24.

5. The digital core 3D real-scene modeling method based on close-range photogrammetry technology according to claim 1, characterized in that: In step 5 above, multiple camera shooting points are taken around the core segment m times, where m ≥ 3.

6. The digital core 3D real-scene modeling method based on close-range photogrammetry technology according to claim 1, characterized in that: The core images and coordinates of the three control points corresponding to each core segment were imported into ContextCapture software to perform 3D real-world modeling of the core.

Images