At the center of the Eclectic screen is a 3D display of the geometry. This display is controlled by several menus. In the top right corner of the screen is the View menu. The azimuth, elevation and twist angles, as well as the scale (zoom) factor are numerically displayed here - clicking the boxes next to the numbers sets the angles to zero and the scale factor to 1.0. Below the numerical display are six buttons that set the geometry in the six orthogonal views - a seventh button in the center sets the angles and scale factor to a convenient, full-view (of both the geometry and bounding box), off-orthogonal orientation.
Users manually rotate and scale (zoom) the geometry through the mouse. A right mouse click centers the display over the area where the mouse was clicked. Dragging the mouse with the right mouse button depressed will scale the geometry during up-down mouse movements, and will twist (angular movement in the direction of a clock hand) the geometry. Moving the mouse with the left mouse button depressed rotates the geometry in the elevation (up-down mouse movement) and azimuth (right-left mouse movement) orientations.
Below the View menu is the Units box. Users can cycle through a selection of various units (inches, feet, yards, meters, and millimeters).
Below the Units box is the Display Menu. Users can select whether the geometry should be displayed as solid (no shading), flat shaded, smooth shading, or as wireframe.
Below the Display Menu and Test Model button is the Hide menu. Parts, surfaces, and polygons can be rendered invisible through the Hide feature. Selecting part(s), surface(s), or polygon(s) and then depressing the Hide button, renders the selected entities invisible. The Restore button makes all entities visible.
In the top left corner of the screen is the Model menu. Inside Eclectic there are two separate entities: the mesh and the underlying (base) geometry. Users can select to display the base geometry only, the mesh only, or (the default mode) both the base geometry and mesh.
Below the Model menu and above the Select menu are two buttons: the ?? button pops up a window that displays information (ID number, bounding box location, etc) about the selected entity, while the ALL button selects the entire geometry. The Select menu is important since it not only effects how the geometry is displayed but it also determines which operations can be performed. The Select menu has numerous options: Parts, Surfaces, Polygons, Points, and Vertices. Additionally, the Select menu contains buttons to grey shade the object (as opposed to the default color mode) and to display the bounding box (FACE). Note that the seventh (central) button in the View menu sets the scale factor such that the entire bounding box is displayed.
The Command Menu, with various tabs, dominates the bottom of the screen. This menu contains selection-dependent operations. The operations will be described in the next sections of this manual.
In the bottom left corner of the screen is the Queue menu. Recent commands can be undone, and undone commands can be redone using the buttons in this menu. The queue of recent commands can be edited by using the Undo-Redo command in the Edit part of the top menu bar.
The top menu bar has File, Edit, and Memory selections. Under File, users can open and save Eclectic-native files (which load much faster than imported geometry files). Under File, users can also import and export mesh files. Supported file formats for import include Wavefront OBJ, Stereolithography STL, raw triangles RAW, BRL-CAD g, XPATCH facet, and FRED fac and ASC.fac. Eclectic exports files in the Wavefront OBJ file format. The Exit command is also part of the File menu.
The Edit menu contains a Undo-Redo command that pops up a window in which the recent command queue can be edited. The Memory menu contains a command that pops up a window to report in detail on memory usage.
To explain the operations in Eclectic, this section lists the steps required to re-mesh a simple geometry. The geometry consist of a cylinder that was meshed within a commercial CAD system (IDEAS). Sample Wavefront obj and RadTherm tdf files can be downloaded from the Tutorials page.
Import: From the menu bar at the top of the screen, use the File->Import command to import the file called IdeasCylinder.obj. During import, Eclectic displays a message that informs users that the Wavefront OBJ file did not contain vertex normal data. Many of the operations in Eclectic require vertex normals. The message continues to explain that Eclectic created a vector normal for each vertex by analyzing the normal of the polygons that surround each vertex.
Test Model: Run the Eclectic model test (button is below the Display menu box). Eclectic states the model passed the tests. Eclectic tests for high aspect (i.e. long and skinny) polygons and for twisted quadrilaterals. If the model fails the test, Eclectic will provide tools and procedures to fix the geometry. Close the Model pop-up window.
Select/Display: Set the Select menu to part (PART) and then to surface (SURF). Note that the original geometry had three parts: top, side, and bottom. Eclectic preserves these parts, and made each part a surface.
Original Mesh Original Model
Long, skinny triangles Each part (top, side, bottom) is
Top disconnected from sides a separate surface
Mesh Length: The Mesh Length box under the Select tab in the Command Menu sets the finest mesh resolution for the re-meshing process. Users can elect to use the default Mesh Length and quickly go through the re-meshing process, evaluate the density of the resulting mesh, and then restart the whole process with a revised value for Mesh Length if the users determine that the default value is inadequate. Alternatively, users can select ALL of the geometry and then use the ?? command (both buttons are located above the Select menu). The information pop-up will list the X-Y-Z extents of the geometry - users can set the Mesh Length to achieve the mesh density according to this information. For this tutorial, leave the Mesh Length at its default value of 1.000. Note that when users type in a new value for Mesh Length that should hit return after entering the number.
Prep 1: Depress the Set Ready to Prep1 button in the Command menu (Select tab). View the geometry surfaces - note that Eclectic divided the side part into four surfaces. Eclectic realized that the normal vectors associated with the side part faced in various directions relative to the bounding box for the side part/surface so it divided the part into four surfaces facing the four sides of the bounding box (to view this, Select->FACE and then depress the central button in the View menu box).
Surface Cutting: Try surface cutting. Select surfaces (SURF) and then select ALL of the geometry. The surface cutting commands in the Prep1 (Surf) Command Menu should become active (when in SURF mode). Surface cut with respect to normals (WRT Normals) Selected (or ALL PARTs). Eclectic informs the users that no surface cutting operation was performed because none was needed. Surface cutting is required only when the boundary between surfaces is not smooth. Even though the surface boundaries may appear smooth when displayed, it is still wise to try surface cutting to see if Eclectic can find any surface that requires repair.
Prep 2: Depress the Set Ready to Prep2 button in the Command menu box (Prep1 tab). The geometry is now shown with hard edges (red lines), soft edges (white lines), and hard vertices (violet circles) displayed. Red edges and vertices will be retained, within the constraints imposed by the resolution of the mesh, during the re-meshing process. None of the displayed red edges and vertices in this model should be retained since it is not necessary to retain the lines along the side or those particular vertices along the top and bottom. Any hard edge or vertex that need not be kept should be removed (made soft). Unfortunately there is no command to remove (soften) hard edges. There is a command, however, to switch between hard and soft designations for vertices. When creating a mesh, Eclectic will "snap" to, if any, hard vertices whenever it positions a vertex.
After Prep 1 After Prep 2
Eclectic divided sides into 4 surfaces Hard (red) and soft (white) edges
Removing Hard Vertices: Before trying to select a vertex, set the Select mode to vertex (VTX). To select a vertex, left mouse click within a polygon defined by the vertex, near the vertex. The mouse must be positioned over a polygon - clicking when the mouse is not over a polygon will not select anything. When there are multiple vertices close together (after re-meshing there will be a number of these multiple vertices along the top and bottom edges), take care to click on a polygon that contains the desired vertex (as opposed to a polygon that contains a vertex close to the desired one). Eclectic permits the selection of multiple vertices (and other entities), simply keep selecting vertices - with the catch is that you must click in a different polygon every time. To de-select a vertex, click near the vertex in the same polygon that was clicked upon to select the vertex originally. Once the vertex is selected (the violet circle turns blue), depress the SOFT<->HARD VTXs button under the Prep2 tab in the Command menu box.
Meshing: Depress the Set Ready to Mesh button in the Command menu box (Prep2 tab). With the select mode set at either PART or SURF in the Select menu box, depress the MESH button in the Command menu box (Mesh tab). The resulting mesh has minor problems - the following operations will fix these problems.
Handling Missing Polygons: Four polygons are missing from the top of the cylinder. There are various ways of fixing this problem - we'll look at three solutions: Fill Triangle, Joining Vertices, and re-meshing with hard vertices.
Fill Triangle: Users can fill the void between three vertices with a triangle. With the Select mode set to vertex (VTX), select the three vertices for the triangle you want to create. See "Removing Hard Vertices" above for a description of selecting vertices - remember to click within a different polygon each time in order to select a new vertex. With three vertices selected, depress the FILL TRIANGLE button under the Mesh tab in the Command menu box. If you like, you can split the quadrilateral on top for the sake of "permitting" heat gradients (or whatever) to flow up the side of the cylinder and across the top (i.e. match the number of polygons along the top edge of the cylinder side with the number of polygons along the edge of the top). To split a quadrilateral, you must be in vertex (VTX) Select mode because you must click within the quadrilateral you want to split near the "vertex (corner) that you want split". Depressing the SPLIT QUAD button in the Mesh tab of the Command menu creates two triangles out of the quadrilateral.
Joining (Stitching) Vertices: Joining vertices results in moving a vertex so that it "overlaps" another existing vertex. This operation can only be performed in Select vertex (VTX) mode. Select two vertices and then depress the STITCH (Join VTXs) button under the Mesh tab in the Command menu. The first vertex that is selected does not move - the second selected vertex is moved to the position of the first selected vertex. If there are multiple vertices, users may have to apply this operation several times to achieve the desired result.
Re-meshing: The problem with the missing polygons occurred at the top of the hard edges (i.e. between surfaces). If we made the vertices hard at these places (along the top edge, in the middle of the missing polygons), then Eclectic would be forced to try to position a vertex in there. Note that these vertices had been made hard during Prep2 (we made them soft during Prep2). To try a different re-mesh, first eliminate the existing mesh: in PART of SURF Select mode, select ALL, and depress the unMESH button under the Mesh tab. In VTX Select mode, select the four vertices at the top of the hard edges, and make them hard using the SOFT<->HARD VTXs button under the Prep2 tab in the Command menu box. Depress Set Read to Mesh button under the Prep2 tab. Finally, select ALL and MESH. We now have a different problem - some of the vertices on top do not line up with vertices along the top of the edge. This can be fixed by manually moving (STITCH) vertices - but Eclectic provides an automated procedure for aligning the mesh between surfaces or parts - welding.
After MESH operation After vertex STITCH
(Surface display mode) (Vertex display mode)
Welding: Welding aligns the meshes of adjoining parts and/or surfaces. Go into the PART Select mode. You could use the SURF Select mode but you would need to either select the four side surfaces or repeat the operation 4 times for each side surface. First, select the mesh whose vertices who want to be shifted. Second, select the mesh that you want to remain fixed (note that you can select multiple parts or surfaces of the second type - this operation will modify only the first selected part or surface). Finally, depress the WELD SELECTED button under the Mesh tab in the Command menu box. This mesh looks fine, until one zoom in on the top edge - vertices along the side and along the top need to be stitched together. If you're not sure if there are multiple vertices at a location, one way to check is to try the STITCH operation by trying to select a "side" vertex and a "top" vertex - it is often easier to see that the vertices are distinct when they are both selected. Also, stitching together identical vertices does no harm. Vertices along the bottom also need to be stitched together.
Mesh density: The overall density (resolution) of the mesh can be adjusted by the MESH LENGTH (Select tab). Also, the mesh density of each surface or part can be set independently - this requires meshing the surfaces and parts individually (instead of selecting ALL before depressing the MESH button). To experiment with these settings, select ALL, depress unMESH (Mesh tab), and then move to the appropriate tab.
Export: Since you want to export only the new mesh, select MESH as your model mode (menu box in top left corner of screen). Remembering this step is not crucial since Eclectic will pop-up a "are you sure" window during export informing you what model is going to be exported. From the menu bar at the stop of the screen select File->Export. When exporting, one needs to type in the file extension (i.e. TEST.OBJ, not just TEST) contrary to Windows convention.
RadTherm/MuSES Operations: The mesh can now be opened within a finite elements analysis code such as RadTherm or MuSES. Additional mesh processing may be required. There are free edges in the mesh. In other words, despite stitching within Eclectic, finite elements codes may think that adjoining polygons are not really adjacent (i.e. they do not share exactly the same vertices). Within RadTherm/MuSES, free edges can be displayed by selecting View->Display Free Edges from the top menu bar. This problem can be readily fixed (assuming that you do want conduction to occur across these edges) by going to the Geometry->Edit tab. Use the Condense operation to "join" ("stitch") together adjacent vertices. All vertices within the specified separation will be combined. If the operation is successful, the free edges will disappear from the display. If the specified separation distance is too small (i.e. smaller than the distance between the vertices you want stitched together), try the operation again with a larger value for the specified separation distance.
This tutorial covered most of the major operations in Eclectic. Other operations include:
HIDE parts, surfaces, and polygons from displaying (Hide menu box). RESTORE displays all entities.
JOIN parts and surfaces (Select tab).
CORNER ANGLE setting (Select tab) that helps determine where surfaces are created.
FORM NEW PART (and thus allowing the creation of new surfaces) from selected polygons and surfaces (Select tab).
Combining surfaces with regards as to how vertex normals are treated (VTX N under Prep1 tab): surfaces are be treated independent of each other (INDEP) or treated like a single surface (DEP).
Polygons can be flipped (i.e. normal reversed) (Pgn N under Prep1 tab).
Adjusting the boundary grid (Prep1 tab) for selected part(s). Using this operation, the boundary grid can be rotated with respect to the surfaces contained within the selected part (one should later mesh only the part(s) selected during this operation). First, select the part(s). Depress the ENABLE button in the Adjust Boundary Grid box (Prep1 tab). Using the mouse, left button drag the hands around the dials to rotate the bounding box (on some machines, you may have to depress the box above the numeric display to activate the corresponding dial). SET GRID when done.
All commands are discussed in Section 3 of this manual.
2.3 Basics of Operation
Eclectic reads in the imported mesh and displays the geometry. In Eclectic, geometry is composed of polygons, surfaces, and parts. When reading in the mesh, Eclectic retains the grouping of polygons into parts. Eclectic adds in an intermediate level of grouping: surfaces. Surfaces are groupings of polygons; parts are groupings of surfaces. Initially, Eclectic assigns a unique surface to each part. Surfaces are key in Eclectic.
Eclectic works by projecting a rectilinear mesh from a bounding box onto the geometry. For each surface, Eclectic projects the rectilinear mesh from one - and only one - side of the bounding box. This projection works optimally when all of the polygons on each surface are close to being parallel to the side of the bounding box used for that surface. Consequently, the division of the geometry into surfaces is key to a successful re-meshing operation. Eclectic will automatically divide parts into surfaces as part of Prep1 (the first stage of the re-meshing operation). Sometimes the automatic division will not be optimal - for these cases, Eclectic provides user-controlled surface cutting commands.
From the Prep1 menu box, users can adjust the bounding box for each surface. The bounding box can be rotated so that its sides are parallel to the surfaces. The next operation, Prep2, identifies edges in the geometry. During Prep2 soft edges (displayed in white) can be transformed into hard edges (displayed in red). Discontinuities in surface curvature at hard edges will always be preserved by Eclectic, while the mesh may attempt to smooth out surface continuities at soft edges. From this menu, users can also edit vertices - combining vertices and switching between hard/soft vertices. As with the edges, hard vertices will be retained during re-meshing while soft vertices may not be.
With the polygons grouped into surfaces, edges and vertices designated as soft or hard, and bounding boxes associated with surfaces, the geometry is ready to be re-meshed. Users can elect to mesh the geometry by parts or surfaces instead of meshing the entire geometry at once. When the geometry is re-meshed by parts or surfaces, different meshing densities can be used for each part or surface.
After re-meshing, users can edit the mesh: create triangles, combine triangles into quadrilateral elements, split quadrilaterals into triangles, and delete elements. Eclectic also provides a tool to weld parts of the mesh together - this is useful when different mesh densities were applied to different parts or surfaces. Users can then export the mesh as a Wavefront OBJ file.
2.4 In Case of Code Crashes
Eclectic is still under development. As such, the code does not have extensive error-handling capability. Currently the code handles many errors by crashing. These errors include errors and/or unsupported attributes in imported geometry files, commands performed out-of-sequence, and reaching resource limits. To minimize the number of crashes try the following:
- Operate only on small pieces of large models (i.e. mesh one or few parts at a time).
- Whenever possible, break large models into smaller files and operate on them individually.
- Many crash situations cannot be duplicated. Trying the same steps again often results in success.
- Try again. Each time you process the model you will refine your method and style. Eclectic will be very appreciative of refinements in your method.
- Use a platform with more resources (i.e. memory).
- Eclectic quickly runs out of resources when you open new models. Before loading in a new, different model, exit Eclectic and restart.
Users seem to achieve the best results when Eclectic is used in conjunction with other tools, especially with CAD packages like Rhino. Some operations are best performed with other tools - use each tool optimally.
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Version 1.0 January 15, 2003 |