201007618 九、發明說明： 【發明所屬之技術領域】 本灰明涉及種邊界元素提取方法及其 其涉及一種從雜亂點雲中接 糸統，尤 統。 -中棱取邊界兀素的方法及其電腦系 【先前技術】 產品品質驗證的程中，誤差分析已經成為 ❹ 置獲取工件㈣ 卩°，_做法是使用點雲獲取裝 合），而後將點二：夕個三維離散點組成的點的集 料進行處理，‘二=電腦，執行相應軟體對點雲資 絲㈣似^取农對應的邊界元素，也就是工件的 蚤、\杜所^徵。然後，透過迭代擬合法將實際工件和 量測工件所得的 貝丨不工件和 與理論設計圖擒中行對齊’以痛定實際工件 做法的對齊效否存在誤差，是’此種 &不间且特殊位置還不能完全對齊。 另外隨著影像技術的發展，人臉識別、特徵匹配 有限元分析等徒術的引用，業界人員對邊界元素的：： 度和提取速度h求也越來越高，而傳統技術 元素提取的以還不能達到此#要求。 订邊界 【發明内容】 鑒於以上内&，有必要提供-種邊界元素提取方法及 其電腦糸統’ ^自動提取雜亂點雲的邊界元素，包括提 邊界點和触邊界特徵，提高了料元素的提取精度和提 取速度。 6 201007618 ❹ -種邊界元素提取方法，該方法包括：獲取量測工件 所產生的點雲資料及組成點雲三角網格化曲面的三角形的 最大邊長；根據該最大邊長將所獲取的點雲建立成三角網 格化曲面；從上述三角網格化曲面中提取邊界點；根據邊 界點的向量變化情況對所述邊界點進行分組；將每組邊界 點分別擬合成直線和圓；在進行直線容差判斷和圓容差判 $後確定適合每組邊界點的邊界特徵；及輸出所述邊界特 :種提取邊界元素的電腦系統，該電腦系統包括：獲 心格I:獲取量測工件所產生的點雲資料及組成點雲 -角網格化曲面的三角形的最大邊長； 用於根據所述最大邊長將所媒兩认—角網格化早70 ’ *面;邊界二=:::=立成三角網格化 取邊界點；及創建單元用^述—角網格化曲面令提 圓，在合成直線或 界點的邊界特徵，並μ所確定適合每組邊 统，====，述邊界元素提取方法及其電腦系 ::層紙點雲的邊界元素 =2,還可以提 速度。 n了邊界疋素提取精度和 【實施方式】 佳實施境:、本 運购翻包括—影像量測機 201007618 台1及與該影像量測機台1相連接的電腦2。 ^ 所述影像量測機台1用於對工件3進行量測，獲取該 • 工件3的點雲資料。該點雲資料包括點的三維座標、點的 . 標識和點雲總數。在本實施例中，由於工件3每個部位的 密度不同、結構不同，所以，影像量測機台1所獲取的點 雲為雜亂點雲。 電腦2内存儲一邊界元素提取系統20，如圖2所示， 該邊界元素提取系統20包括獲取單元21、三角網格化單 ⑩ 元23、邊界點提取單元25和創建單元27，用於從雜亂點 雲中提取邊界元素，該邊界元素包括邊界點和邊界特徵。 因此，本實施例中的提取邊界元素包括提取邊界點和創建 邊界特徵，具體而言，邊界元素提取系統20對所獲取的點 雲建立三角網格化曲面（以下簡稱為“三角網格面”），從三 角網格面中提取邊界點，並根據所提取的邊界點創建點雲 的邊界特徵。 參閱圖3,係本發明邊界元素提取方法較佳實施例之 作業流程圖。 步驟S1，獲取單元21獲取影像量測機台1量測工件 3所產生的點雲資料及獲取用戶輸入的組成三角網格面的 三角形的最大邊長。其中，所述獲取包括獲取單元21接收 影像量測機台1線上量測工件3的點雲資料，及透過打開 資料檔案的形式獲取影像量測機台1先前量測工件3所得 到的點雲資料。所述最大邊長為用戶自定義的邊長，其約 等於點雲中相鄰點之間距離的平均值。 201007618 獲取輯料最大邊長將所 取邊界Γ，邊界點提取單元25從上述三角網格面中提 步驟S7，創建蕈开4 的邊界特徵，並輸出所創麵邊的邊界點創建點雲 參閱圖4,係圖3中步驟 業流程圖。 建二角網袼面的具體作 -维S300’三角網格化單元23根據點雲資料十點的 :=計算得到所述點雲的包圍盒，對該包園盒= 所社〜雲㈣中每個點的標識填人到相應的分組中。 所心組絲料元小正方㈣邊長可 點雲總數計算得$。 長及 步驟S302,獲取點雲中尚未與其他點組成三角形刊 的任-點’作為三角形T0的第一頂點m ❹ 第一頂點m最近的點，作為三角形τ〇的第二頂點 ν驟S304 ’連接第一頂點D1和第二頂點D2得到一 條邊B0,且將該邊B0加入一邊佇列中。 々步驟S306,根據所述最大邊長找出組成該三角形τ〇 的第三頂點D3，構建該三角形τ〇且將該三角形τ〇的另 外兩條邊添至所述邊佇列，即除了邊Β〇外的另外兩條邊。 其中’二角形Τ0的内角不能太小’如1度、2度’在尋找 第二頂點D3時，要優先考慮所組成的角大於25度的點， 然後再考慮所組成的角小於25度但角度卻不能太小的 201007618 點。在本較佳實施财，雜成㈣、於3产。 步驟謂，對上述三㈣T〇進行外接球判斷和純角 判斷，以找出除了上述第三頂點％外能與邊則構成三角 形的點D、。所述外接球判斷是指利用數學法則如最小二乘 法，將三角形T(m合成一個球，三角形τ〇透過其三個頂 點與所述球連接’且該球内沒有點存在，三角網格化 23利用純角原則在該球上尋找點〇、，點D、與邊β〇組成三 角形τ、，該三角形r與三角形τ〇之門的201007618 IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to a method for extracting a boundary element and relates to a system for picking up a cloud from a messy point cloud. - The method of taking the boundary element in the middle edge and its computer system [Prior technology] In the process of product quality verification, the error analysis has become the acquisition of the workpiece (4) 卩 °, _ the practice is to use the point cloud to obtain the assembly), and then the point Two: The aggregate of the points consisting of three-dimensional discrete points is processed, 'two = computer, the corresponding software is applied to the point cloud (4) to take the corresponding boundary element of the farmer, that is, the workpiece's 蚤, \杜所^征. Then, through the iterative fitting method, the actual workpiece and the measured workpiece are not aligned with the theoretical design map, and there is an error in the alignment effect of the actual workpiece. It is 'this kind of & Special locations are not yet fully aligned. In addition, with the development of image technology, face recognition, feature matching finite element analysis and other references, the industry's people: the degree of: and the speed of extraction of the boundary elements are getting higher and higher, while the traditional technical elements are extracted. This # requirement cannot be reached yet. Boundary [Invention] In view of the above &, it is necessary to provide a kind of boundary element extraction method and its computer system ' ^ automatically extract the boundary elements of the chaotic point cloud, including the boundary point and touch boundary features, improve the material elements Extraction accuracy and extraction speed. 6 201007618 ❹ - A method for extracting a boundary element, the method comprising: obtaining a point cloud data generated by the measuring workpiece and a maximum side length of a triangle constituting the triangular cloud meshing surface of the point cloud; the obtained point according to the maximum side length The cloud is formed into a triangular meshed surface; the boundary points are extracted from the triangular meshed surface; the boundary points are grouped according to the vector variation of the boundary points; each set of boundary points is respectively fitted into a straight line and a circle; The linear tolerance judgment and the round tolerance judgment determine the boundary feature suitable for each set of boundary points; and output the boundary special: a computer system for extracting boundary elements, the computer system includes: obtaining the heart I: obtaining the measurement workpiece The generated point cloud data and the maximum side length of the triangle constituting the point cloud-angle meshed surface; for meshing the two media-accepting angles according to the maximum side length by 70 '* faces; boundary two= :::=Organize the triangle mesh to take the boundary point; and create the unit with the angle-corner mesh surface to make the circle, in the boundary of the synthetic line or boundary point, and μ determined to suit each group of sides, = ===, the boundary Pigment coated paper :: method and computer-based point cloud boundary element = 2, the speed can be improved further. n The accuracy of boundary element extraction and [Embodiment] Good implementation: This shipment includes: Image measuring machine 201007618 Table 1 and computer 2 connected to the image measuring machine 1. ^ The image measuring machine 1 is used for measuring the workpiece 3, and acquiring the point cloud data of the workpiece 3. The point cloud data includes the three-dimensional coordinates of the point, the point of the marker, and the total number of point clouds. In the present embodiment, since the density of each part of the workpiece 3 is different and the structure is different, the point cloud acquired by the image measuring machine 1 is a messy point cloud. A boundary element extraction system 20 is stored in the computer 2. As shown in FIG. 2, the boundary element extraction system 20 includes an acquisition unit 21, a triangular meshing unit 10 element 23, a boundary point extraction unit 25, and a creation unit 27 for The boundary element is extracted from the clutter point cloud, and the boundary element includes a boundary point and a boundary feature. Therefore, extracting the boundary element in the embodiment includes extracting the boundary point and creating the boundary feature. Specifically, the boundary element extraction system 20 establishes a triangular meshed surface for the acquired point cloud (hereinafter referred to as a “triangular mesh surface”). ), extracting boundary points from the triangular mesh surface, and creating boundary features of the point cloud according to the extracted boundary points. Referring to Figure 3, there is shown a flow chart of a preferred embodiment of the boundary element extraction method of the present invention. In step S1, the acquiring unit 21 acquires the point cloud data generated by the image measuring machine 1 for measuring the workpiece 3 and obtains the maximum side length of the triangle of the triangular mesh surface input by the user. The obtaining includes the acquiring unit 21 receiving the point cloud data of the measuring workpiece 3 on the image measuring machine 1 on the line, and acquiring the point cloud obtained by the image measuring machine 1 previously measuring the workpiece 3 by opening the data file. data. The maximum side length is a user-defined side length that is approximately equal to the average of the distances between adjacent points in the point cloud. 201007618 Obtaining the maximum side length of the piece to take the boundary Γ, the boundary point extracting unit 25 extracts the step S7 from the above triangular mesh surface, creates the boundary feature of the split 4, and outputs the boundary point of the created side edge to create a point cloud. Figure 4 is a flow chart of the steps in Figure 3. The specific work of the built-in two-dimensional network-dimensional S300' triangular meshing unit 23 calculates the bounding box of the point cloud according to the point cloud data:======================================= The identification of each point is filled into the corresponding group. The core group of the silk element is small square (four) side length can be calculated by the total number of points cloud. In step S302, a point in the point cloud that has not been formed into a triangle with other points is obtained as the point closest to the first vertex m 三角形 of the first vertex m of the triangle T0, as the second vertex of the triangle τ〇, step S304 ' Connecting the first vertex D1 and the second vertex D2 to obtain one side B0, and adding the side B0 to the side array. Step S306, finding a third vertex D3 constituting the triangle τ 根据 according to the maximum side length, constructing the triangle τ 〇 and adding the other two sides of the triangle τ 添 to the side 伫 column, that is, except for the edge Β The other two sides of the raft. The inner angle of the 'diopter Τ0 cannot be too small' such as 1 degree, 2 degrees. When looking for the second vertex D3, priority should be given to the point where the angle formed is greater than 25 degrees, and then the angle formed is less than 25 degrees. The angle is not too small for 201007618 points. In this preferred implementation, it is produced in four (four) and three. The step is to perform a circumscribed ball judgment and a pure angle judgment on the above three (four) T , to find a point D which is a triangle shape except for the third vertices. The circumscribed ball judgment refers to using a mathematical rule such as a least square method to combine a triangle T (m is a ball, a triangle τ 〇 is connected to the ball through its three vertices) and no point exists in the ball, and the triangle meshes 23 using the pure angle principle to find the point 〇 on the ball, the point D, and the edge β 〇 to form the triangle τ, the triangle r and the triangle τ 〇
<間的夾角必須為鈍角。 步驟S3H)，點IT與邊B0組成三角形τ'，三角網格化 單元23將該三角形r的另外兩條邊，即除了邊Β〇的另外 兩條邊，添加到所述邊仔列中。 步驟S312，三角網格化單元23迴圈邊仔列中的邊， 並重複執行步驟S308至步驟S312 ’直至所有的邊被迴圈 完，完成構建的三角形組成了點雲的三角網格面。 於步驟S308中，在進行純角判斷時，本較佳實施例 優先考慮與三角形T0組成120度夹角的三角形。然而， 三角網格化單元23利用外接球判斷和鈍角判斷的方法可 能會同時找到多個點D、，但其最終只能確定—個點D、為 最佳點，與邊Β0組成三角形Τ、。例如，若三角網格化單 元23利用外接球判斷和鈍角判斷的方法同、 和點D2、，邊Β〇與點Dl、可組成三角形打、、邊則淑點 D2、可組成三角形打、’則三角網格化單元23需確定在三 角形ΤΓ和Τ2、中邊Β〇的對角哪個更大，若邊Β〇在三角 形H、中的對角大於在三角形Τ2、中的對角，則最終較點 201007618 〃 D1是所要找到的最佳點；反之，若邊BO在三角形T2、中 .的對角大於在三角形ΤΓ中的對角，則最終確定點取、是 要找到的最佳點。 • 參閱圖5,係圖3中步驟S5提取邊界點之具體作業流 . 程圖。 >步驟S500,邊界點提取單元25從所述三角網格面中 獲取當前判斷點週圍的三角形及每個三角形的頂點。 步驟S5〇2,計算每個頂點被當前判斷點週圍的三角形 所佔用的次數，如圖6和圖7所示，點工、點2、點3、點 4和點5分別為當前判斷點〇週圍的三角形的頂點。在圖6 :’點1、點2、點3、點4和點5被當前判斷點〇週圍的 三角形所佔用的次數分別為2 ;在圖7中，點2、點3和點 4被當前判斷點〇週圍的三角形所佔用的次數 1和點5被佔用的次數分別為1。 一步驟S504,依次判斷所述頂點被當前判斷點〇週圍的 ❹二角形所佔用的次數是否均大於1。 若步驟S504的判斷結果為是，即所述頂點被佔用的 次數均大於！，則步驟S5〇6確定該當前判斷點為内點，芦 $直接進人步驟關。如圖6所示，由於所有的頂點被當 則判斷點0週圍的三角形所佔用的次數均大於卜 圖6所示的當前觸點〇被確定為内點。、 若步驟S504的判斷結果為否’即所述頂點中存在至 少一個頂點被佔用的次數等Μ，則步驟⑽確定該當前 判斷點為邊界點，如圖7所示，由於點工和點5被佔用的 11 201007618 次數分別為1，因此，圖7所示的當前判斷點〇被確定為 邊界點。 ~ 步驟S510，邊界點提取單元25判斷三角網格面十的 ' 點是否都被進行了邊界點判斷。若是’則直接結束流程； . 若還有點未進行邊界點判斷，則返回步驟S500,將該點作 為當前判斷點，重新執行步驟S5〇〇至步驟S51〇直至所有 的點均被進行了邊界點判斷。The angle between the < must be an obtuse angle. In step S3H), the point IT and the side B0 form a triangle τ', and the triangular meshing unit 23 adds the other two sides of the triangle r, that is, the other two sides except the edge, to the side row. In step S312, the triangular meshing unit 23 loops back the edges in the side row, and repeats steps S308 to S312' until all the edges are looped, and the completed triangle constitutes a triangular mesh surface of the point cloud. In step S308, in the case of performing the pure angle determination, the preferred embodiment preferentially considers a triangle which forms an angle of 120 degrees with the triangle T0. However, the triangle meshing unit 23 may use the method of circumscribed ball judgment and obtuse angle judgment to find multiple points D at the same time, but it can only determine that the point D is the best point and the triangle 组成 is formed by the edge Β0. . For example, if the triangular meshing unit 23 uses the method of the circumscribing ball judgment and the obtuse angle judgment, and the point D2, the edge Β〇 and the point Dl, can form a triangle, and the edge can be a D2, can form a triangle, ' Then, the triangular meshing unit 23 needs to determine which of the diagonals of the triangles ΤΓ and Τ2 is larger, and if the diagonal of the edge 三角形 in the triangle H is greater than the diagonal of the triangle Τ2, then the final Point 201007618 〃 D1 is the best point to be found; conversely, if the diagonal of the edge BO in the triangle T2, the middle is greater than the diagonal in the triangle ,, then the point is determined to be the best point to find. • Refer to Figure 5, which is the specific job flow for extracting the boundary points in step S5 in Figure 3. > In step S500, the boundary point extracting unit 25 acquires a triangle around the current judgment point and a vertex of each triangle from the triangular mesh plane. Step S5〇2, calculating the number of times each vertex is occupied by the triangle around the current judgment point, as shown in FIG. 6 and FIG. 7, the point, point 2, point 3, point 4, and point 5 are the current judgment points respectively. The vertices of the surrounding triangles. In Figure 6: 'Point 1, Point 2, Point 3, Point 4, and Point 5 are occupied by the triangle around the current judgment point 分别 respectively; in Figure 7, point 2, point 3, and point 4 are currently The number of times 1 and 5 occupied by the triangle around the point 〇 is 1 respectively. In step S504, it is sequentially determined whether the number of times the vertex is occupied by the ❹-triangle around the current judgment point 均 is greater than 1. If the result of the determination in step S504 is YES, that is, the number of times the vertex is occupied is greater than! Then, step S5〇6 determines that the current judgment point is an inner point, and the re-$ directly enters the step. As shown in Fig. 6, since all the vertices are judged, the number of times occupied by the triangle around the point 0 is larger than the current contact 所示 shown in Fig. 6 is determined as the inner point. If the result of the determination in step S504 is no, that is, the number of times at least one vertex in the vertex is occupied is equal, step (10) determines that the current judgment point is a boundary point, as shown in FIG. 7, due to the point and point 5 The number of occupied 11 201007618 is 1, respectively, so the current judgment point 图 shown in Fig. 7 is determined as the boundary point. ~ In step S510, the boundary point extracting unit 25 judges whether or not the 'points of the triangular mesh surface ten are subjected to the boundary point determination. If it is 'then, the flow is directly ended. If there is still a point where the boundary point judgment is not made, the process returns to step S500, and the point is taken as the current judgment point, and step S5〇〇 to step S51〇 are performed again until all the points are subjected to the boundary point. Judge.
參閱圖8’係圖3中步驟S7創建邊界特徵之具體作 流程圖。 業 步驟S700 ,創建單元27分別以圖5中提取的邊界點 為當前點，並以該當前點為中心層層向外展開，計算所展 開的邊界點在三角網格面上的向量之間的角度關係。 步驟S702，創建單元27根據角度變化情況對所有邊 界點進行分組，並將每組邊界點分別擬合成直線。具體而 吕，創建單元27於步驟S702中將角度變化相差很小的邊 ©界點放在一個組中，並由此得到了多組邊界點，然後將每 組邊界點擬合成直線。例如，若邊界點a與邊界點b在三 角網格面上的向量之間的角度為60度，邊界點a與邊界： c在三角網格面上的向量之間的角度為1度，則表明邊界 點a與b的向量之間的角度變化很大，而邊界點a鱼邊界 點c的向量之間的角度變化很小，因此，邊界點&與邊界 點b會被分在不同組中，而邊界點&與邊界點c 同一個組中。 刀 步驟S704,判斷用於擬合所述直線的點與該擬合後的 12 201007618 •直線之間的差值是否均小於—個預設的直線容差。 . #㈣，4 斷結果為是，則直接進入步驟 S714;若步驟S704中的判斷結果為否，則表明所擬合的 .直線不適合該組邊界點’步驟S7〇6，創建單元27利用最 • 小二乘法將該組邊界點擬合成圓。 步驟S708,判斷用於擬合成圓的點與該擬合後的圓之 間的差值是否均小於一預設的圓容差。 #步驟漏巾㈣斷結果衫，職接進入步驟 S714 ;好驟S7〇8中的判斷結果為是，且步驟s寫中擬 ，了至少兩個圓，則步驟S71〇中創建單元27根據圓的半 徑、圓的向置及圓心連線與所述向量之間的關係來判斷所 擬合的圓之間是否能構建圓柱。在本實施例中，創建單元 2曰7構建圓柱的條件為：上述擬合的圓的半徑相同、圓的向 !之間的角度為〇度或18〇度，且圓心連線與所述向量之 間的角度也為0度或18〇度。 Φ 若步驟S710中的判斷結果為否，則直接進入步驟 S7^4 ;若步驟S71〇中的判斷結果為是則步驟奶2，創 建單元27將滿足上述條件的圓構建成圓柱。 步驟S7H ’創建單元27輸出適合每組邊界點的邊界 特徵4邊界特徵包括直線、圓和圓柱。例如，若邊界點 提取單元25所提取的所有邊界點如圖9 (a)所示，則創 建單元27所創建的邊界特徵如圖9 (b)所示。 上—在本實施例中，所述直線容差和圓容差可由用戶提前 什算出，其約等於點雲中相鄰點之間距離的平均值。另外， 13 201007618 不同區域的點雲的密度可能會不同，在點雲密度較大的區 * 域，可以將所述平均值乘以一個係數，以得到該區域的直 • 線容差和圓容差。其中，所述係數可能為0.1、0.2或0.3。 . 另外，在本實施例中，所述創建單元27還可以先將 . 每組邊界點擬合成圓。若用於擬合成圓的點與該擬合後的 圓之間的差值不小於所述圓容差，則表明所擬合的圓不適 合該組邊界點，創建單元27利用最小二乘法將該組邊界點 擬合成直線，然後進行直線容差判斷。當創建單元27所擬 〇 合的圓至少為兩個時，才判斷所擬合的圓之間能否構建圓 柱。 本發明雖以較佳實施例揭露如上，然其並非用以限定 本發明。任何熟悉此項技藝之人士，在不脫離本發明之精 神及範圍内，當可做更動與潤飾，因此本發明之保護範圍 當視後附之申請專利範圍所界定者為準。 【圖式簡單說明】 圖1係本發明提取邊界元素的電腦系統較佳實施例之 營 運行環境圖。 圖2係本發明邊界元素提取系統之功能單元圖。 圖3係本發明邊界元素提取方法較佳實施例之作業流 程圖。 圖4係圖3中步驟S3建立三角網格化曲面之具體作 業流程圖。 圖5係圖3中步驟S5提取邊界點之具體作業流程圖。 圖6和圖7係本發明獲取當前判斷點週圍的三角形及 14 201007618 每個三角形的頂點之示意圖。 圖8係圖3中步驟S7創建邊界特徵之具體作業流程 圖。 圖9係本發明創建邊界特徵之示意圖。 【主要元件符號說明】 影像量測機台 1 電腦 2 工件 3Referring to Figure 8', a specific flow chart for creating a boundary feature in step S7 of Figure 3 is shown. In step S700, the creating unit 27 respectively uses the boundary point extracted in FIG. 5 as the current point, and expands outwardly with the current point as a center layer, and calculates the boundary point of the expanded boundary point between the vectors on the triangular mesh surface. Angle relationship. In step S702, the creating unit 27 groups all the boundary points according to the angle change condition, and fits each set of boundary points to a straight line. Specifically, the creating unit 27 places the edges of the angle change with little difference in the step S702 in a group, and thereby obtains a plurality of sets of boundary points, and then fits each set of boundary points into a straight line. For example, if the angle between the boundary point a and the vector of the boundary point b on the triangular mesh surface is 60 degrees, the boundary point a and the boundary: c the angle between the vectors on the triangular mesh surface is 1 degree, then It is shown that the angle between the vectors of the boundary points a and b varies greatly, and the angle between the vectors of the boundary point a of the fish boundary point c is small, so the boundary point & and the boundary point b are divided into different groups. Medium, while the boundary point & is in the same group as the boundary point c. The knife step S704 determines whether the difference between the point for fitting the straight line and the fitted line 12 201007618 • the straight line is less than a preset straight line tolerance. If the result of the determination in step S704 is no, it indicates that the fitted line is not suitable for the set of boundary points 'step S7〇6, and the creation unit 27 utilizes the most. • The least squares method fits the set of boundary points into a circle. In step S708, it is determined whether the difference between the point for fitting the circle and the circle after the fitting is less than a preset circular tolerance. #Step missing towel (4) breaks the result shirt, the job proceeds to step S714; the judgment result in the good step S7〇8 is YES, and at least two circles are written in the step s, then the creation unit 27 according to the circle in step S71 The radius, the orientation of the circle, and the relationship between the center line and the vector determine whether a cylinder can be constructed between the fitted circles. In this embodiment, the condition that the creating unit 2曰7 constructs the cylinder is that the radius of the circle fitted above is the same, the angle between the directions of the circle is 〇 or 18〇, and the center line is connected with the vector. The angle between them is also 0 degrees or 18 degrees. Φ If the result of the determination in step S710 is NO, the process proceeds directly to step S7^4; if the result of the determination in step S71 is YES, the step milk 2, the creation unit 27 constructs a circle satisfying the above condition into a cylinder. The step S7H' creating unit 27 outputs a boundary feature 4 suitable for each set of boundary points. The boundary features include a straight line, a circle, and a cylinder. For example, if all the boundary points extracted by the boundary point extracting unit 25 are as shown in Fig. 9(a), the boundary features created by the creating unit 27 are as shown in Fig. 9(b). Upper - In the present embodiment, the linear tolerance and the round tolerance can be calculated by the user in advance, which is approximately equal to the average of the distances between adjacent points in the point cloud. In addition, 13 201007618 the density of point clouds in different regions may be different. In the region* where the point cloud density is large, the average value can be multiplied by a coefficient to obtain the direct line tolerance and roundness of the region. difference. Wherein, the coefficient may be 0.1, 0.2 or 0.3. In addition, in this embodiment, the creating unit 27 may also first fit each set of boundary points into a circle. If the difference between the point used to fit the circle and the fitted circle is not less than the circle tolerance, it indicates that the fitted circle is not suitable for the set of boundary points, and the creating unit 27 uses the least squares method to The group boundary points are fitted to a straight line, and then the line tolerance is judged. When the circle to be merged by the creating unit 27 is at least two, it is judged whether or not the circle can be constructed between the fitted circles. The present invention has been described above by way of a preferred embodiment, and is not intended to limit the invention. Any person skilled in the art will be able to make changes and refinements without departing from the spirit and scope of the invention, and the scope of the invention is defined by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing the operating environment of a preferred embodiment of a computer system for extracting boundary elements of the present invention. Figure 2 is a functional unit diagram of the boundary element extraction system of the present invention. Fig. 3 is a flow chart showing the preferred embodiment of the boundary element extraction method of the present invention. Figure 4 is a flow chart showing the specific operation of creating a triangular meshed surface in step S3 of Figure 3. FIG. 5 is a flow chart showing the specific operation of extracting the boundary point in step S5 of FIG. 3. 6 and 7 are schematic diagrams showing the triangles around the current judgment point and the vertices of each triangle of 201007018. Figure 8 is a flow chart showing the specific operation of creating a boundary feature in step S7 of Figure 3. Figure 9 is a schematic illustration of the creation of boundary features in accordance with the present invention. [Main component symbol description] Image measuring machine 1 Computer 2 Workpiece 3
邊界元素提取系統 20 獲取單元 21 三角網格化單元 23 邊界點提取單元 25 創建單元 27 獲取量測工件所得到的點雲資料 S1 將所獲取的點雲建立成三角網格化曲面 S3 從所述三角網格化曲面中提取邊界點 S5 根據所提取的邊界點創建點雲的邊界特徵 S 7 15Boundary element extraction system 20 acquisition unit 21 triangle meshing unit 23 boundary point extraction unit 25 creation unit 27 acquires the point cloud data S1 obtained by measuring the workpiece, and establishes the acquired point cloud into a triangular meshed surface S3 from the Extracting boundary points in a triangular meshed surface S5 Creating boundary features of a point cloud based on the extracted boundary points S 7 15