Demonstration teaching method applied to Chaozhou wood carving handicraft

Abstract

The present invention provides a demonstration teaching method applied to Chaozhou wood carving handicrafts, comprising setting a cloud-based demonstration teaching device to be interconnected with a computer, setting a threshold value on a digital modeling library of wood carving based on full-system scanning 3D automatic imaging technology, and performing dichotomy processing to derive a dynamic drawing of the projection content; projecting the dynamic drawing onto wood based on established projection technology and laser scanning imaging technology, roughly identifying the deformed wood during carving through laser vertices, and feeding back the result to the computer, the computer identifying a certain surface in the three-dimensional model to which the visual field belongs, and reversely distorting the deformation of the projection content caused by the special-shaped curtain; taking screenshots of consecutive frames of the established digital model, obtaining a dynamic drawing by extracting the line draft, and performing reverse processing on the dynamic drawing when the line draft is attached to the model as the mapping center. The present invention improves the convenience of teaching, expands the function of cultural communication channels, and at the same time lowers the learning threshold and stimulates potential creativity.

Description

Technical Field

[0001] The invention relates to the field of Chaozhou wood carving teaching, and in particular to a demonstration teaching method applied to Chaozhou wood carving handicraft. Background Art

[0002] Chaozhou wood carving is characterized by subtraction of wood materials, and the overall three-dimensional presentation of the work, with the characteristics of 360-degree circular carving and viewing perspective, and hollow carving technology. It is different from clay sculptures, reliefs and other carving types that add to the raw materials or make partial movements or flattening. In the production process of Chaozhou wood carving, the content of the material is first conceived and described, and the flat dynamic drawings are presented on the wood. Then the craftsmen use their experience and technology to convert and carve it into three dimensions. Since this process is not suitable for novice carpenters in the non-master-apprentice teaching mode, it is not suitable for the current gathering of people in the teaching site interrupted by the epidemic. In addition, wood carving is a subtractive process. Its characteristics restrict the transformation of flat dynamic drawings into three-dimensional sculptures. The process must go through a process of shaping from shallow to deep. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the deficiencies in the prior art, the present invention provides a demonstration teaching method applied to Chaozhou wood carving handicrafts to solve the problems raised in the above background technology.

[0005] (2) Technical solution

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a demonstration teaching method applied to Chaozhou wood carving handicrafts, including a demonstration teaching device applied to Chaozhou wood carving handicrafts, which includes a rotating base, a projection lamp, a projection fixed-point recognition laser detector and a rotation angle identifier, the rotating base is provided with an active checkpoint and a circular projection lamp moving track, the projection lamp is installed on the circular projection lamp moving track, the projection fixed-point recognition laser detector is specifically a laser emitter and feedback device, and the projection fixed-point recognition laser detector and the projection main lamp are installed on the same horizontal line, the rotation angle identifier is installed at the edge of the rotating shaft at the bottom of the rotating base, the rotation angle identifier sets a standard positive viewing angle reference line on the base, and the rotation measurement angle performed with the reference line is fed back to the computer;

[0007] The steps are as follows:

[0008] Step 1: The demonstration teaching device is connected to the cloud and a computer. Based on the full-system scanning 3D automatic imaging technology, a digital modeling library of wood carvings is created. A continuous frame screenshot of the established digital model is taken, and a dynamic drawing is obtained by extracting the line drawing. The threshold is set on the computer, and a binary method is used to process and derive the dynamic drawing of the projection content.

[0009] Step 2: Based on established projection technology and laser scanning imaging technology, the dynamic drawing is projected onto the wood. The laser vertex roughly identifies the wood deformed during carving and feeds the information to the computer. The computer identifies the view area and a certain surface in the 3D model, and then reverses the distortion of the projected content caused by the irregular screen.

[0010] Step 3: Attach the dynamic drawing to the model as the center of the texture and perform reverse processing on the dynamic drawing;

[0011] Step 4: By reducing the density of the turning points in the dynamic drawing of the digital model, the actual semi-finished wood carving is roughly matched, so that the prototype semi-finished wood carving continues to take shape and improve under the dynamic drawing. The finer the actual object, the finer the line drawing of the dynamic drawing.

[0012] Step 5: Place the wood on the turntable base. The computer will identify the base's rotation angle and rotate the dynamic drawing perspective to achieve a three-dimensional presentation of the dynamic drawing that adapts to the multiple faces of the wood.

[0013] As a further preference, the binary processing in step one includes model exposure, screenshots, enhanced separation effects, output of video materials, and extraction of contour lines of different components as line drawings. The binary processing process specifically includes recording a 360-degree rotation display video of the digital model, setting a strong front exposure for the model, forming a white block in the illuminated part, indicating the retained wood area, taking a screenshot of each frame of the video, opening the screenshot with Photoshop, decolorizing, adjusting the curves, increasing the highlight value, increasing the shadow value, making the outer contour clear, representing the retained wood part in the view with white, and representing the carved-out wood part with black, that is, setting batch thresholds, and exporting a binary diagram.

[0014] As a further preference, the dynamic drawing projection process in step 2 includes data writing, simulating irradiation light, rotating model algorithm, projection algorithm and data output.

[0015] As a further preference, the simulated irradiation light specifically simulates the scanning direction of a laser scanner, and the moving route of the projection lamp is stored in the computer and parameterized to 1, so as to achieve the correspondence between the virtual and real laser irradiation directions.

[0016] As a further preference, the projection algorithm calculates the projection of the current model in three-dimensional space and under illumination based on the rotated three-dimensional model, and outputs it as a two-dimensional projection based on the viewport position. The projection algorithm specifically separates the yin and yang of the continuous frame screenshots of the digital model material, that is, separates the carved out part from the retained part, and performs strong front exposure on the digital model in a head-on perspective, thereby obtaining a basic binary processing effect.

[0017] As a further preference, the data output is based on the established projection technology and laser scanning imaging technology, and the dynamic drawing is projected onto the wood. At the same time, the deformed wood during carving is roughly identified through laser positioning, and the feedback is given to the computer, so that the computer can clearly understand the carving progress, thereby projecting the dynamic drawing content under the progress, and corresponding the prototype shape with the cylindrical tangent surface of the original wood material, so as to calculate the depth information required for carving from the geometric cylindrical tangent surface of the raw material to the surface of the final work, providing a basis for depth measurement, and visually expressing the depth information to the carving learner in red, yellow and green, wherein the presentation method of the depth information is similar to that of a contour map.

[0018] As a further preferred embodiment, when the depth information is visually expressed in red, it indicates that the depth has not been reached; when the depth information is visually expressed in yellow, it indicates that the depth will be reached; and when the depth information is visually expressed in green, it indicates that the depth has been reached.

[0019] As a further preference, the projection content in step 2 is specifically a dynamic drawing, which includes specific image information, yin and yang diagrams, and carving progress color diagrams.

[0020] As a further preference, in the screenshots of the established digital model in step three, for the digital model, the front view is used as a single perspective, the model is rotated and screenshots are taken to obtain thickness information, which is different from traditional painting and dynamic drawings of wood that reflect images from different perspectives on different sides, and the sculptor performs depth-related processing on his own.

[0021] (3) Beneficial effects

[0022] The present invention provides a demonstration teaching method applied to Chaozhou wood carving handicrafts, which has the following beneficial effects:

[0023] 1. Based on the established digital model library of classic intangible cultural heritage Chaozhou woodcarvings, dynamic drawings are processed and a yin-yang analysis of the materials retained and removed is presented. Because this device is targeted at beginners, the complexity of the woodcarving replicas in the database is limited. Suitable teaching materials should not be too complex in terms of three-dimensional layers, but should have the thickness of elements and an operating space to represent the occlusion relationship between elements. The rotatable base corresponds to the rotation angle of the computer view, allowing the operator to experience the three-dimensionality of the dynamic drawings and shape them into the wood. During rotation, the required thickness and position of the elements can be observed, thus achieving the difficulty of the basic course and training the thinking of three-dimensional transformation. The projected image is projected onto the wood and rotates as the viewing angle of the wood changes, transferring the teaching scene to everyday situations such as the home, enhancing the convenience of Chaozhou woodcarving teaching. This method is based on the context of handicrafts. The projection target is to reflect the human eye. The carving aims to establish human two-dimensional thinking, which has teaching significance. Human carving involves observation, feedback, and the establishment of a key awareness of generalized form, thus achieving the difference between traditional machine carving thinking.

[0024] 2. Improve the convenience of teaching, expand the function of cultural communication channels, and provide digital media guidance for entry-level learning of Chaozhou wood carving. Beginners can copy and learn classic works after establishing basic comprehension skills, and transfer the teaching scene to more daily scenes such as home, which improves the convenience of teaching and the frequency of learning with interest, so that the public can experience the production process of traditional handicrafts with their own hands. At the same time, it adapts to the interruption of gathering teaching scenes in the epidemic environment, and transfers teaching tasks online, so that the master-apprentice model of traditional craft teaching can adapt to the trend of modern digital education. It not only breaks the normal state of art copying in a two-dimensional manner, but also makes art copying move to a broader dimension, and plays a practical role in promoting the cultivation of craftsmen.

[0025] 3. Lower the learning threshold and stimulate potential creativity. The digital models of Chaozhou wood carving classics are subjected to threshold adjustment similar to rubbing printing, and the dichotomy analysis of the yin and yang analysis of the parts to be retained or removed is processed. The computer cloud computing program, etc., guides beginners in the conversion of two-dimensional to three-dimensional, thereby lowering the learning threshold and increasing the possibility for non-practitioners to come into contact with traditional handicrafts, thereby stimulating their creative potential in the process of experiencing traditional handicrafts and injecting new vitality into the tradition and innovation of intangible cultural heritage. DETAILED DESCRIPTION

[0026] The invention discloses a demonstration teaching method applied to Chaozhou wood carving handicraft, and the invention is further described in detail below through specific embodiments.

[0027] This embodiment provides a demonstration teaching method for Chaozhou woodcarving handicrafts, including a demonstration teaching device for Chaozhou woodcarving handicrafts, which includes a rotating base, a projection lamp, a projection fixed-point recognition laser detector, and a rotation angle identifier. The rotating base is provided with an active checkpoint and a circular projection lamp moving track. The projection lamp is mounted on the circular projection lamp moving track. The projection fixed-point recognition laser detector is specifically a laser emitter and feedback device, and the projection fixed-point recognition laser detector and the projection main lamp are installed on the same horizontal line. The rotation angle identifier is installed at the edge of the rotating axis at the bottom of the rotating base. The rotation angle identifier sets a standard positive viewing angle reference line on the base, and the rotation angle measured based on the reference line is fed back to a computer.

[0028] The rotating base is disc-shaped, upon which the wood for carving is placed. By fixing the sculptor's perspective, the projection light only needs to be within the primary viewing angle, while still providing a three-dimensional representation. This reduces weight and costs, and facilitates teaching. The rotating base also adjusts the angle of the wood carving, meeting the requirements of Chaozhou woodcarving's three-dimensional carving techniques. The disc secures the wood in place, with a movable stop that locks in place according to the shape of the wood's base. A circular projection light track is mounted on the rotating base, and a motorized pusher moves the projection light, ensuring a fixed angle between the light and the carving strokes, maintaining optimal projection quality.

[0029] The projection light takes into account the unique shape of the wood used as the projection screen material. Since the engraver's position is fixed, the primary projection light is positioned according to the engraver's primary perspective. Due to the profound interaction between the engraver and the wood during the engraving process, the projection beam does not penetrate the shadow cast by the hand. To ensure the integrity of the dynamic drawing projection, an angle interval is set between the projection light, the wood, and the engraving tool. The projection light content is derived from a computer-generated binary analysis of the digital model, distinguishing between the retained and removed parts (retained as yang, removed as yin). This projection content ensures that the dynamic drawing shifts with the engraving perspective and remains clear as the engraving progresses, overcoming the shortcomings of traditional dynamic drawings, which are flat and gradually blur as the engraving progresses. Since the engraver maintains a high level of concentration and visual focus on the engraving material, the projected light must ensure a clear projection of the dynamic drawing while maintaining appropriate brightness to protect the engraver's eyesight.

[0030] The projection fixed-point recognition laser detector is a laser emitter and feedback device. It is based on the established and gradually improved laser detection technology. As an auxiliary to the projection main light, it is installed on the same horizontal line as the projection main light.

[0031] As the carving progresses, the wood deforms vertically, further complicating the base upon which the projection is projected. Therefore, the principle of laser detection is employed: a laser emitter fires a laser dot matrix from a central reference line toward the periphery of the semi-finished product, obtaining position feedback. (Due to the opacity of wood, laser emission is obstructed, and position is determined by converting the laser emission speed into a distance formula.) This process is then calculated on a computer, which moves the known dot matrix spectrum to the corresponding position on the digital model. This distorts the dynamic drawing, which is then derived into a projection to accommodate the changing shape of the wood during the carving process. The dynamic drawing is corrected by horizontally rotating the viewing angle and by fixed points during the vertical in-depth carving process. Ultimately, laser beam-assisted projection positioning ensures the accuracy of the dynamic drawing on the changing wood.

[0032] The steps of the demonstration teaching method applied to Chaozhou wood carving handicraft are as follows:

[0033] Step 1: The demonstration teaching device is connected to the cloud and a computer. Based on the full-system scanning 3D automatic imaging technology, a digital modeling library of wood carvings is created. A continuous frame screenshot of the established digital model is taken, and a dynamic drawing is obtained by extracting the line drawing. The threshold is set on the computer, and a binary method is used to process and derive the dynamic drawing of the projection content.

[0034] Step 2: Using established projection and laser scanning imaging technologies, the dynamic drawing is projected onto the wood. The laser vertex roughly identifies the wood deformed during carving and feeds the information back to the computer. The computer then identifies which face of the 3D model the field of view belongs to and reverses the distortion of the projected content caused by the irregular screen.

[0035] Step 3: When the line drawing is attached to the model as the center of the texture, the dynamic drawing is processed in reverse;

[0036] Step 4: By reducing the density of the turning points in the dynamic drawing of the digital model, the actual semi-finished wood carving is roughly matched, so that the prototype semi-finished wood carving continues to take shape and improve under the dynamic drawing. The finer the actual object, the finer the line drawing of the dynamic drawing.

[0037] Step 5: Place the wood on the turntable base. The computer will identify the base's rotation angle and rotate the dynamic drawing perspective to achieve a three-dimensional presentation of the dynamic drawing that adapts to the multiple faces of the wood.

[0038] In this embodiment, the binary processing in step 1 includes model exposure, screenshots, enhanced separation effects, video material output, and extraction of contour lines of different components as line drawings. The binary processing process specifically includes recording a 360-degree rotation display video of the digital model, setting a strong front exposure for the model, forming a white block in the illuminated part, indicating the area where wood is retained, taking a screenshot of each frame of the video, opening the screenshot in Photoshop, decolorizing, adjusting the curves, increasing the highlight value, and increasing the shadow value to make the outer contour clear. The retained wood part in the view is represented by white, and the carved-out wood part is represented by black, that is, batch threshold setting, and exporting the binary diagram.

[0039] The dynamic drawing projection process in step 2 includes data writing, simulating irradiation light, rotating model algorithm, projection algorithm and data output.

[0040] Among them, when making videos, the projection algorithm specifically separates the yin and yang of the continuous frame screenshots of the digital model material, that is, separates the carved out part from the retained part, and exposes the digital model from the front in a straight-ahead perspective, thereby obtaining a basic binary processing effect.

[0041] In this embodiment, the binary division process includes data writing, simulating illumination light, rotating the model algorithm, projecting algorithm and data output.

[0042] Specifically, the projection algorithm calculates the projection of the current model in three-dimensional space and under the illumination light based on the rotated three-dimensional model, and outputs it as a two-dimensional projection based on the viewport position. The projection algorithm specifically separates the yin and yang of the continuous frame screenshots of the digital model material, that is, separates the carved out part from the retained part, and performs a strong front exposure on the digital model in the horizontal perspective, thereby obtaining a basic binary processing effect.

[0043] Furthermore, data output is based on established projection technology and laser scanning imaging technology, which projects the dynamic drawing onto the wood. At the same time, through laser positioning, the deformed wood during carving is roughly identified and fed back to the computer, so that the computer can clearly understand the carving progress and project the dynamic drawing content under that progress.

[0044] The prototype being engraved is scanned by a laser scanner to obtain initial point cloud data, which is then stitched together and the closest point algorithm is iterated. ICP is an iterative optimization process based on the least squares method, which is used to find the rigid transformation that optimally aligns two 3D point cloud sets. First, an initial pose estimate is assumed, and then a certain number of control points are selected from one point set. The neighboring points of these points are found in another point set as corresponding points. A transformation is then obtained by minimizing the sum of the squared distances between these corresponding points, and the process is iterated repeatedly until the convergence condition is met. The steps of this algorithm are as follows:

[0045] Assume two point clouds P and Q, with an overlapping area of Ω, and let the position of any point in Ω in P be p i , which is q in Q i , k<=k max is the number of algebraic operations, T k is the k-th transformation matrix between P and Q:

[0046] (1) Set the initial transformation matrix T 0 , the Euclidean distance mean square error threshold is γ, and the maximum number of selections is k max , perform iterative initialization;

[0047] (2) Find the point cloud set p k The closest point cloud on Ω

[0048] (3) Solve the transformation matrix T k , so that T k (p k )) is closest to Q, that is Minimum

[0049] (4) Transform p k ,p k+1 =T k (p k )

[0050] (5) If F(T k-1 )-F(T k )<τork>k max The iteration ends. Otherwise, repeat steps (2) to (4).

[0051] After the point cloud is stitched, the wood carving prototype is denoised using the least squares V T The quadratic surface fitting method with PV=min is used to simplify point cloud data. The basic formula is as follows:

[0052]

[0053] Differentiate the coefficients separately to make them zero

[0054]

[0055] where j∈(0,k)

[0056] After finding the coefficients a, b, c, convert them into vector form

[0057]

[0058] According to the first basic formula of the surface:

[0059] (ds) 2 =I=E(dx) 2 +2Fdxdy+G(dy) 2

[0060] E=r x ×r x ,F=r x ×r y ,G=r y ×r y

[0061] And the second basic formula:

[0062] II=-dr×dn=L(dx) 2 +2Mdxdy+N(dy) 2

[0063] L=r xx ×n,M=r xy ,N=r yy ×n

[0064] Thus, the Gaussian curvature and the mean curvature are obtained

[0065]

[0066] The average curvature reflects the flatness and concavity of the surface of the carved prototype, and the Gaussian curvature reflects the bending characteristics of the point. Therefore, the average curvature is used for comparison, and the Gaussian curvature is used to select the points after comparison, thereby completing the simplification of the wood carving prototype point cloud.

[0067] Finally, based on the processed point cloud data, the shape of the wood being carved can be presented dynamically in real time, corresponding one-to-one with the data of the actual wood carving and compared with the prototype shape of the wood carving in the textbook. The computer can clearly understand the carving progress and project the dynamic drawing under this progress.

[0068] The prototype shape is then matched with the cylindrical external surface of the original wood material, so as to calculate the depth information required for carving from the geometric cylindrical external surface of the raw material to the surface of the final work, providing a basis for depth measurement, and visually expressing the depth information to the carving learners in red, yellow and green. The presentation of depth information is similar to that of a contour map.

[0069] When performing depth-related shaping, the sculptor sees a dynamic drawing similar to a contour map, which uses red, yellow and green as symbols and includes information on the area range of the same depth line in proportion. At this time, the computer receives laser depth measurement feedback emitted in the same direction as the projection lamp. Areas within the same depth area that do not reach the specified depth are synchronously displayed by the projection lamp as red / yellow filling.

[0070] When the depth information is visualized in red, it indicates that the depth has not been reached; when the depth information is visualized in yellow, it indicates that the depth will be reached; and when the depth information is visualized in green, it indicates that the depth has been reached.

[0071] Assume that the next step of the teaching material on the computer is arc carving, and the current processing point of the woodcarver is N(x n ,y n ), the radius of the arc is R, and the original equation of the circle center at the origin is

[0072] (1) Determine whether the processing point is outside the arc, on the arc, or inside the arc based on the deviation value.

[0073] The calculation formula of the deviation value is as follows:

[0074] If F n >=0, the processing point is outside the arc; if F n <0, the processing point is inside the arc.

[0075] (2) According to the judgment result, decide in which coordinate direction the red projection line will move one step.

[0076] If F n >=0, in order to reduce the deviation, the projection light should move one step in the -Δx direction. At this time, the coordinates of the next processing point are

[0077] x n+1 =x n-1 , (only consider the absolute value), y n+1 =y n , then the new discriminant function is:

[0078]

[0079] If F n <0, in order to reduce the deviation, the projection light should move one step in the Δx direction, and the coordinates of the next processing point are

[0080] x n+1 =x n ,y n+1 =y n +1, then the new discriminant function is:

[0081]

[0082] (3) Calculate the deviation of the new processing point after the woodcarver carves, which provides the basis for the next step of judgment. When the carving tool starts, it is at the starting point of the arc, then F0 = 0.

[0083] (4) While calculating the deviation, the end point judgment must be performed. If the next unit reaches the end point, the color of the projection light will be changed to yellow. If it has reached the end point, the projection light will be changed to green. The judgment of the end point can convert the distance from the start point to the end point of the required processing arc into the coordinates of the x-axis and y-axis. We know that each step of the projection light is equivalent to the distance moved in the coordinate system. In this way, we can get the number of steps required for the projection light to reach the end point. Based on this number of steps, we perform a subtraction operation. Every time the x-axis or y-axis is fed once, we subtract one from the total number of steps. When the total number of steps is reduced to zero, it means that the end point position has been reached.

[0084] The final output is a dynamic drawing material containing a schematic representation of the depth information of each part. The engraver's brushstrokes, along the increasingly precise drawing, form a fixed angle with the projection light's projection beam. Due to the in-depth interaction between the person and the material during the shaping process, the projection does not penetrate the person's hands, causing obstruction and deformation of the drawing. By limiting the angle between the projection light and the engraving brushstrokes, the shadow only obscures the completed engraving area, without affecting normal engraving. (The dynamic drawing assists beginners in the direction of the engraving brushstrokes: to ensure that the shadows cast by the projection do not obscure the drawing and hinder the recognition of the drawing's content, the shadows are limited to the completed engraving area. The engraving brushstrokes are engraved from the highest point of the outer contour forward and downward. The projection light is positioned at an angle above and in front of the brushstrokes, so that the projection is only generated behind the direction of the brushstroke's advance, that is, the completed engraving area. The projection light moves along the track to the optimal projection position based on the preset starting angle of the engraving brushstrokes and after calculating the fixed optimal projection angle).

[0085] Changing any variable, such as the model's angle, lighting direction, or shape, generates real-time feedback from the computer. Sample models are stored in the mesh, allowing the operator to select any model from the digital library of wood carvings for simulated carving. Slider 01 adjusts from 0 to 360 degrees, corresponding to rotating the base angle in practice, thereby changing the wood carving angle. Slider 02 adjusts from 0 to 1, with 0 representing the starting point of the projection light's movement and 1 the final point. The actual engraving process is combined with the laser feedback device's recognition of progress. When the drawing reaches a certain progress point, the flashlight push blocks on either side of the projection light receive progress information and the "start moving" command.

[0086] The simulated irradiation light specifically simulates the scanning direction of the laser scanner. The moving route of the projection lamp is stored in the computer and parameterized to 1, so as to achieve the correspondence between the virtual and real laser irradiation directions.

[0087] Since the computer records the engraving brush angles during the digital model engraving process, and the projection light forms a fixed optimal projection angle with the engraving brush, the position of the projection light relative to the engraving brush can be determined. Using the above algorithm, the trajectory of the electric pushers pushing the projection light to the corresponding position is obtained. In this way, the electric pushers on both sides of the projection light obtain the required track position information according to the engraving progress.

[0088] The rotation model algorithm uses the wood base as the rotation plane and the direction perpendicular to the wood base as the rotation direction, synchronously rotating the three-dimensional model sample and the model being carved.

[0089] Finally, the projection algorithm calculates the projection of the current model in three-dimensional space and under the illumination light based on the rotated three-dimensional model, and outputs it as a two-dimensional projection material based on the viewport position.

[0090] Computers create three-dimensional models of classic Chaozhou woodcarvings and establish a digital model library. This device, interconnected with the cloud and physical objects, utilizes established and gradually expanding holographic scanning 3D automatic imaging technology to create a digital model library of classic intangible cultural heritage. The computer sets thresholds and performs basic dichotomy processing to derive rough projection material: the computer captures continuous frames of the three-dimensional model, adjusts the threshold, and performs a dichotomy analysis of the removed and retained parts, exporting the resulting material to the projector. Because woodcarvings follow the principle of generalization, the level of detail in the drawings progresses from coarse to fine, and the shape changes, manual digital modeling of the teaching material is required to preserve the carving process information, allowing the computer to read the prototype of the woodcarving. This allows the computer to predict deformation after the laser fixed-point feedback of the woodcarving stage, allowing the drawing to be reversed to avoid distortion during projection. Furthermore, as the carving progresses, the drawing depth changes.

[0091] A laser scanner roughly scans and locates any wood deformation during carving, providing feedback to a computer. The computer then processes any distortion in the draft and exports it to the projector, ensuring that the draft remains displayed properly and aiding in projecting the draft with improved accuracy. Due to the richness of Chaozhou woodcarving elements and the complex deformations involved, this instructional process, focused solely on the copying nature of the work, uses a database of 3D models of the source material to predict wood deformation and summarize existing deformation information. Once local deformation is aligned with a specific surface on the 3D model, the draft is accurately corrected and exported using the precise data from the 3D digital model.

[0092] During the actual projection operation, the laser scanning device is in the same position as the projection lamp in the device. After the computer identifies which side of the three-dimensional model the field of view belongs to, it reversely distorts the deformation of the projection content caused by the irregular screen. After export, the dynamic drawing still presents a normal composition on the deformed wood.

[0093] Among them, the flat dynamic drawing is attached to the preset prototype model as a texture. The computer will record the deformation of the dynamic drawing, such as stretching (lifted by the drum surface) and compression (squeezed by the concave surface), and process the dynamic drawing in the reverse direction of the deformation effect: actual stretching - preset compression / actual compression - preset stretching, so as to achieve a normal, non-distorted dynamic drawing that can be recognized by the naked eye in the actual projection;

[0094] Reverse processing, the computer performs three-dimensional modeling of the Chaozhou wood carving classic works and establishes a digital model library. The device is connected to the cloud and the real object. Based on the established and gradually expanded holographic scanning 3D automatic imaging technology, the digital modeling library of the classic intangible cultural heritage is set by the computer for threshold setting and basic dichotomy processing, thereby deriving the dynamic drawing of the projection content. Since the wood carving is based on the principle of generalization, the fineness of the dynamic drawing changes from coarse to fine, and the shape changes, it is necessary to manually digitally model the teaching material copy and save the carving process information so that the computer can read the prototype of the wood carving, so that the deformation can be predicted after the laser fixed-point feedback wood carving stage, and the dynamic drawing can be reversed to avoid distortion during projection. At the same time, the depth of the dynamic drawing switches when the carving goes deeper. The computer takes continuous frame screenshots of the three-dimensional model and adjusts the threshold at the same time. It performs dichotomy analysis on the carved and retained parts and exports the projector;

[0095] A laser scanner roughly scans and locates any wood deformation during carving, providing feedback to a computer. The computer then processes any distortion in the animated sketch and exports it to the projector, ensuring that the animated sketch remains displayed properly and aiding in projecting the sketch with improved accuracy. Due to the richness of Chaozhou woodcarving elements and the complex deformations involved, this instructional process, focused solely on the copying nature of the work, utilizes a database of 3D models of the source material to predict wood deformation and summarize existing deformation information. Once local deformations are aligned with specific surfaces on the 3D model, the animated sketch is accurately corrected and exported using the precise data from the 3D digital model.

[0096] For the image sequence {L1, L2…L N}, the mean of the sequence can reflect the distortion-free scene L to a certain extent GT， Therefore, a frame L(x, y, t) at time t in the distorted image sequence is converted to the sequence mean image As the neural network input. Then the deformation vector field of the distorted image frame to the sequence mean image is obtained by the convolutional neural network. It describes the warping of the image frame L(x, y, t) at time t to the sequence mean image The spatial mapping relationship between corresponding points, that is,

[0097] I(x, y)=I[( ˉ x, ˉ y)+d(x,y)] (1)

[0098] Among them, d(x,y) is the shape variable.

[0099] Then, bicubic B-sample interpolation is performed through the spatial transformation network to obtain the restored image

[0100] I(x′,y′,t)=Γ[I(x,y,t)] (2)

[0101] That is, for any point X in L, X = [x, y] T , can be obtained by a set of size s x ×s y Image interpolation using a grid of control points

[0102]

[0103] in φ i,j is the mesh control point with coordinates (i, j), and B is the B-spline basis function, which describes the weight of the mesh control point at point X in the deformation field.

[0104]

[0105] By using such a set of B-spline control point grids, an optimization algorithm is applied to minimize the objective function

[0106] c=argminΨ[I(x,y),I(x,y)] (5)

[0107] The optimal grid parameters can be obtained to restore the actual carving position after distortion, so that the projected dynamic drawing can show the accurate position even on the deformed wood.

[0108] Due to the in-depth interaction between humans and the materials during the shaping process, the projection does not penetrate the human hand, causing obstruction and deformation of the dynamic drawing. The limited angle of the projection light and the carving brushstrokes ensures that the shadow only obscures the completed carving part, without affecting the normal carving process (the dynamic drawing assists beginners in the direction of the carving strokes: to ensure that the shadows produced by the projection do not obstruct the dynamic drawing and do not hinder people from recognizing the content of the dynamic drawing, the shadows are limited to the completed carving area. The carving stroke is carved from the highest point of the outer contour forward and downward. The projection light is located at an angle above and in front of the brushstroke, so that the projection is only produced behind the direction of the brushstroke, that is, the completed carving area. The projection light moves along the track to the optimal projection position after calculating the fixed optimal projection angle based on the preset carving stroke starting angle). Specific projection operation: After a series of processing and interpretation of the modeling view by the computer, the dynamic drawing content is recorded as video material, and the projector plays the video material. Individual differences among carvers, such as interruptions to the carving process caused by their daily routines, their learning progress, and the speed of their carving, all influence the pauses and speed of the video playback. This playback setting should be tracked by the computer, allowing for automatic adjustments. This tracking capability is specific to projector operation. To address the three-dimensional nature of Chaozhou woodcarving, the wood is placed on a turntable base. The computer identifies the base's rotation angle and dynamically rotates the perspective of the drawing, achieving a three-dimensional presentation that adapts the dynamic drawing to the multifaceted wood. While copying classic works, users develop a reading comprehension process similar to that of a two-part rubbing of the original carving, fostering a transition between horizontal and vertical transformations and the semantics of the carving movements for subsequent woodcarving creations. This approach lowers the barrier to learning traditional craftsmanship, enhances the preservation of Chaozhou woodcarving, and fosters the possibility of a wider audience. This has profound implications for intangible cultural heritage crafts, which are people-oriented, rely on manual labor, and cultivate public awareness. This device is suitable for copying small and medium-sized, basic Chaozhou woodcarving works, providing a good transition to entry-level art and offering a wider range of opportunities for potential practitioners to experiment, thereby inspiring the public's potential for inheriting and innovating traditional handicrafts. This device serves as a teaching tool and represents a new exploration of aesthetic education models.

[0109] In this embodiment, the projection content in step 2 is specifically a dynamic drawing, which includes specific image information, yin and yang indications, and carving progress color indications.

[0110] Furthermore, in step three, in the screenshots of the established digital model, for the digital model, the orthographic text is used as a single perspective, the model is rotated and screenshots are taken to obtain thickness information. This is different from the traditional painting and the dynamic drawings of wood that reflect images from different perspectives on different sides. The engraver performs depth-related processing on his own.

[0111] Furthermore, the engraving process can be divided into three stages, depending on the different observations and engraving requirements. Stage 1: When engraving the outer contour, hollowing out the corners like a rubber stamp allows for projection. However, when engraving the hollowed-out portion, retaining the corners will obstruct the dynamic drawing and the engraving, rendering it ineffective. For advanced turning tools, engraving from the bottom up will fail. For large tools like drilling, turning, and cross-sectioning, the shadows themselves are too large to provide sufficient hints. Solution: Project dynamic reference lines, trace with a black pen, and then cut automatically. Based on a learning logic of gradual progress and the teaching of basic shape summarization, the dynamic drawing content is divided into three stages: To assist in establishing basic geometric shapes, the dynamic drawing uses projected auxiliary lines as its content, requiring a black pen to trace the auxiliary lines and make incisions as practical operations; because the engraving tools used in the initial stage are large saws, drill guns, etc., the engraving direction is not simply along the dynamic drawing outline, and these tools cast large shadows under the projection light, disrupting the line of sight. Therefore, the content is projected dynamic auxiliary lines. The dynamic auxiliary lines switch with the rotation angle of the base. The auxiliary lines mark the starting points from each face of the basic solid geometric body. With the help of positioning points, the basic shape is manually cut, reflecting the transformation of row and column thinking and continuous line construction thinking, and leveraging the advantages of fast calculation and accuracy of computer-based dynamic drawing data. During the process of constructing the three-dimensional shape, the frame projection adapts to the rotation of the observation angle, so that the visual information of the flat receiving end forms a three-dimensional concept in the human brain.

[0112] Phase 2—The projection content is a dynamic drawing. The dynamic drawing includes detailed image information, yin and yang diagrams, and color indications of the carving progress. When this line drawing is reattached to the model as a texture, it becomes distorted due to the difference between two-dimensional and three-dimensional. The deformation trajectory generated by the projection deformation simulated by the texture is reversed to process the dynamic drawing, such as changing convex to concave, elongation to shortening, etc., to adapt to the actual projection, thus deriving the dynamic drawing of the projection content. Based on established projection technology, the dynamic drawing is projected onto the wood. At the same time, laser positioning is used to roughly identify the wood deformed during carving and feedback is provided to the computer. The computer recognizes that the field of view belongs to a certain surface in the 3D model, and then reverses the distortion of the projected content caused by the irregular screen. After exporting, the dynamic drawing still presents a normal composition on the deformed wood. By reducing the density of positioning points at each turning point in the digital model, a rough fit is applied to the actual semi-finished wood carving. This allows the initial prototype to continue to take shape under the rough dynamic drawing. As the prototype becomes more refined, the dynamic drawing shows more detailed components, which conforms to the current workshop's assembly line work model from large-scale to fine-detailed carving. Due to the intensive interaction between humans and the raw material during the shaping process, the projection does not penetrate the human hand, causing obstruction and deformation of the dynamic drawing. In response to the three-dimensional characteristics of Chaozhou wood carving, the wood is placed on a turntable base. The base's rotation angle is determined by the computer and rotated according to the dynamic drawing's perspective, achieving a three-dimensional presentation that adapts the dynamic drawing to the multi-faceted wood.

[0113] In the process of copying classic works, users develop reading comprehension thinking similar to that of a two-part rubbing to the original carving.

[0114] When carving an outline, hollowing out corners like a rubber stamp allows for projection. However, when hollowing out a part, retaining the corners creates an obstruction between the dynamic drawing and the engraved part, rendering it ineffective. For advanced turning tools, carving from the bottom up will fail. For large tools like drilling, turning, and cross-sectioning, the shadows themselves are too large to be fully implied. Solution: Project dynamic reference lines, trace with a black pen, and then cut automatically. Based on a progressive learning process and the principle of summarizing basic shapes, the dynamic drawing content is divided into three stages. To assist in establishing basic geometric shapes, the dynamic drawing uses projected auxiliary lines, requiring a black pen to outline the auxiliary lines and make incisions. Because the engraving tools used in the initial stages are large saws and drills, the engraving direction does not simply follow the dynamic drawing outline. These tools also cast large shadows under the projection light, disrupting observation. Therefore, projected dynamic auxiliary lines are used as the content. These lines rotate with the base's rotation angle, marking the starting points from each face of the basic solid. Using these positioning points, the basic form is manually cut, demonstrating the transition from row and column thinking to continuous line construction thinking, leveraging the advantages of fast calculation and precision of computer-based dynamic drawing data. During the construction of the three-dimensional form, the frame projection adapts to the rotation of the viewing angle, allowing the visual information received from the flat surface to form a three-dimensional concept in the human brain. Compared with the three-dimensional dynamic projection on the market, this device: the dynamic reference line stage takes into account that the engraving strokes do not always follow the outer contour, but include the special direction strokes generated according to the characteristics of the tools (drilling, sawing) in the basic form establishment stage, and the flexible use of special direction strokes by the human brain.

[0115] The demonstration teaching device provided in this implementation for Chaozhou wood carving handicrafts is connected to the cloud and the real object. Based on the established and gradually expanding holographic scanning 3D automatic imaging technology, the digital modeling library of classic intangible cultural heritage is processed by computer through threshold setting and basic dichotomy, thereby deriving dynamic drawings of the projection content.

[0116] Based on the established projection technology and laser scanning imaging technology, the dynamic drawing is projected onto the wood. At the same time, the deformed wood in the carving is roughly identified through laser positioning and fed back to the computer. After the computer identifies the field of view to a certain surface in the three-dimensional model, it reversely distorts the deformation of the projection content caused by the special-shaped curtain. After exporting, the dynamic drawing still presents a normal composition on the deformed wood. The established digital model is captured in a series of screenshots, and the line drawing is extracted to create a dynamic draft. When this line drawing is reattached to the model as a texture, it distorts due to the difference between two-dimensional and three-dimensional. The deformation trajectory generated by the projection simulation is reversed to the dynamic draft, such as changing convexity to concavity and elongation to shortening, to adapt to the actual projection. By reducing the density of positioning points at each turning point of the digital model, the actual semi-finished wood carving is roughly matched. The semi-finished wood carving, which is only in its initial form, continues to take shape under the rough dynamic draft. The more refined the actual object, the more detailed the dynamic draft components, which conforms to the current workshop's assembly line work model from large-scale to fine-scale carving. Due to the in-depth interaction between the human and the material during the shaping process, the projection does not penetrate the human hand, causing occlusion and deformation of the dynamic draft. Three-dimensional fill lighting is provided by the main and auxiliary projectors to ensure the integrity of the dynamic draft. In view of the three-dimensional carving characteristics of Chaozhou wood carvings, the wood is placed on a turntable base. The rotation angle of the base is recognized by a computer and the dynamic drawing perspective is rotated, so that the dynamic drawing can adapt to the multi-faceted three-dimensional presentation of the wood.

[0117] The process of copying classic works allows users to develop a reading comprehension process similar to that of copying a two-part rubbing of a carved original. This lowers the threshold for learning traditional crafts, enhances the inheritance of Chaozhou woodcarving, and fosters a wider appreciation of the art form. This has profound implications for the people-oriented, manual, and educational nature of intangible cultural heritage crafts. The device is suitable for copying small to medium-sized, basic Chaozhou woodcarvings, providing a good entry-level transition and offering a wider range of opportunities for potential practitioners to experiment, thereby stimulating the public's potential for inheriting and innovating traditional crafts.

[0118] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A demonstration teaching method applied to Chaozhou wood carving handicraft, characterized by: A demonstration teaching device for Chaozhou wood carving handicrafts includes a rotating base, a projection lamp, a projection fixed-point recognition laser detector, and a rotation angle identifier. The rotating base is provided with an active checkpoint and a circular projection lamp moving track. The projection lamp is mounted on the circular projection lamp moving track. The projection fixed-point recognition laser detector is specifically a laser emitter and feedback device, and the projection fixed-point recognition laser detector and the projection main lamp are installed on the same horizontal line. The rotation angle identifier is installed at the edge of the rotating shaft at the bottom of the rotating base. The rotation angle identifier sets a standard positive viewing angle reference line on the base, and the rotation angle measured by the reference line is fed back to a computer. The steps are as follows: Step 1: The demonstration teaching device is connected to the cloud and a computer. Based on the full-system scanning 3D automatic imaging technology, a digital modeling library of wood carvings is created. A continuous frame screenshot of the established digital model is taken, and a dynamic drawing is obtained by extracting the line drawing. The threshold is set on the computer, and a binary method is used to process and derive the dynamic drawing of the projection content. Step 2: Using established projection and laser scanning imaging technologies, the dynamic drawing is projected onto the wood. The laser vertex roughly identifies the wood deformed during carving and feeds the information back to the computer. The computer then identifies which face of the 3D model the field of view belongs to and reverses the distortion of the projected content caused by the irregular screen. Step 3: Attach the dynamic drawing to the model as the center of the texture and perform reverse processing on the dynamic drawing; Step 4: By reducing the density of the turning points in the dynamic drawing of the digital model, the actual semi-finished wood carving is roughly matched, so that the prototype semi-finished wood carving continues to take shape and improve under the dynamic drawing. The finer the actual object, the finer the line drawing of the dynamic drawing. Step 5: Place the wood on the turntable base. The computer will identify the base's rotation angle and rotate the dynamic drawing perspective to achieve a three-dimensional presentation of the dynamic drawing that adapts to the multiple faces of the wood.

2. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 1, characterized in that: The binary processing in step 1 includes model exposure, screenshots, enhanced separation effects, video material output, and extraction of contour lines of different components as line drawings. The binary processing process specifically includes recording a 360-degree rotation display video of the digital model, setting a strong front exposure for the model, forming a white block in the illuminated part, indicating the area where wood is retained, taking a screenshot of each frame of the video, opening the screenshot in Photoshop, decolorizing, adjusting the curves, increasing the highlight value, increasing the shadow value, making the outer contour clear, representing the retained wood part in the view in white, and representing the carved-out wood part in black, that is, setting batch thresholds, and exporting a binary diagram.

3. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 2, characterized in that: The dynamic drawing projection process in step 2 includes data writing, simulating irradiation light, rotating model algorithm, projection algorithm and data output.

4. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 3 is characterized in that: The simulated irradiation light specifically simulates the scanning direction of the laser scanner. The moving route of the projection light is stored in the computer and parameterized to 1, so as to achieve the correspondence between the virtual and real laser irradiation directions.

5. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 3 is characterized in that: The projection algorithm calculates the projection of the current model in three-dimensional space and under illumination based on the rotated three-dimensional model, and outputs it as a two-dimensional projection based on the viewport position. The projection algorithm specifically separates the yin and yang of the continuous frame screenshots of the digital model material, that is, separates the carved out part from the retained part, and performs a strong frontal exposure on the digital model in a head-on perspective, thereby obtaining a basic binary processing effect.

6. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 5, characterized in that: The data output is based on established projection technology and laser scanning imaging technology, which projects the dynamic drawing onto the wood. At the same time, through laser positioning, the deformed wood during carving is roughly identified and fed back to the computer, so that the computer can clearly understand the carving progress, thereby projecting the dynamic drawing content under the progress, and corresponding the prototype shape with the cylindrical tangent surface of the original wood material, so as to calculate the depth information required for carving from the geometric cylindrical tangent surface of the raw material to the surface of the final work, providing a basis for depth measurement, and visually expressing the depth information to the carving learner in red, yellow and green, wherein the depth information is presented in the format of a contour map.

7. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 6, characterized in that: When the depth information is visually expressed in red, it indicates that the depth has not been reached. When the depth information is visually expressed in yellow, it indicates that the depth will be reached. When the depth information is visually expressed in yellow, it indicates that the depth has been reached.

8. The method for teaching and demonstrating Chaozhou wood carving handicraft according to claim 1, characterized in that: The projection content in step 2 is specifically a dynamic drawing, which includes specific image information, yin and yang diagrams, and carving progress color diagrams.

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