- How can I determine why my surface won't trim?
- The first thing to do is get the problem surface in a scene by itself.
Select the problem surface, click
(this turns everything on and leaves
the surface selected), then click
(this turns the selected surface off) and
.
There are several reasons a surface won't trim:
1. Duplicate Curves: Select the surface and query. The number of child curves will be reported in the message window. Count the curves in your trimming loops and see if they match. If more child curves are reported that you counted in the loops, you have duplicate curves. Set your pick limit to PARAMETRIC. Band pick over a small section of 1 of the parametrics in the loops. The message window should report "1 curve picked". If more than 1 curve is picked you have located one place with duplicate curves. Keep band picking over the parametrics until you eliminate all duplicate curves and the number of child curves matches the number of parametrics you counted.
2. Gaps in Loops: Set the pick limit to POINT. Position the pointer over a vertex in the trimming loop. Click the middle mouse button. This picks all curves attached at this point. Mentally, count the curves that should be attached at this point and compare to the number picked. If less curves are picked that you counted, you have a gap in your loop. If more curves are picked than counted, you could have duplicate curves (be sure you counted all curves, including derived curves, etc.,.., that may be visible and attached at the point in question).
-
What do I do when a surface trims but does not discretize?
- When a surface is trimmed, the surface grid generator
is used to discretize the newly defined surface for visualization purposes.
To do this, point spacings are needed at the ends of the edges defining
the surface. If the point spacings have not been explicitly set,
an arbitrary default spacing is used. These default spacings are sometimes
not sufficient to properly discretize the surface. To correct this,
hit the Esc key or click
to be sure the pick list is cleared. Set your pick limit
to POINT, and position the pointer over one of the end points of a curve
defining the problem surface (preferably one that is not adjacent to another
surface, you want to select only the problem surface). Be sure
the message window reports only one surface picked (you may have to select
a group including the problem surface and narrow the number of visible
surfaces by turning them off and toggling until you can easily pick only
the intended surface). Delete this surface. The original, untrimmed
surface should appear. Set a more appropriate spacing at the curve
end points and re-trim.
If all else fails, save to an iges file with only the problem surface visible. Read the iges file back in with gluing and trimming disabled (-ng -nt from the command line). Check the untrimmed surface for duplicate curves and inappropriate point spacings (spacings that are very large or very small in comparison to the arc length of the adjacent curves).
-
What is the difference between the three different
types of curves: derived, parametric, and physical?
- Derived curves - (indicated by light blue) created by the system
as a boundary of a nurb surface. These curves can not be deleted
apart from deleting the surface. When the surface is deleted (split,
unioned, deleted,...), it's derived curves go with it. These curves
can be split creating two parametrics. Other CAD operations can also
be performed on derived curves creating the appropriate new curves (either
parametric or physical) and leaving the original unchanged.
Parametric curves - (indicated by green) curves defined in the parametric space of a parent surface. These curves can be created several ways: projecting another curve onto a surface, intersecting two surfaces, selecting a surface and extracting the bounding curves,... . The purpose of creating parametric curves ultimately is trimming. When a parametric is being used as the boundary of a trimmed surface, it can not be deleted until after the trimmed surface has been deleted. NOTE: The green color of a parametric curve indicates only that it is a parametric curve. There is no way to select a curve and determine which surface it is associated with, so when a surface is deleted, it is a good idea to also delete it's parametrics at the same time.
Physical curves - (indicated by yellow) curves in 3D space and not associated with any surface. These curves are used for construction. Usually physical curves are used to create a surface. Also they can be created, then projected onto a surface creating a parametric curve. Ultimately, they should be deleted or if they need to be retained, put in a group and deactivated. NOTE: Physical curves should be deleted before gluing. Once a physical curve has been glued to another curve, it can not be unglued and deleted. Once they have been glued, you must save, exit, and read back in with no gluing (-ng) to delete. It won't hurt to leave them glued. It's just better to keep the model as clean (free of extra, unused curves, surfaces,etc.) as possible.
-
Why is it that when I try to intersect one surface with multiple
surfaces only two surfaces get intersected?
- The order in which the surfaces are selected is used to tell the system
how to intersect the surfaces. If a single surface is to be intersected
with multiple surfaces, you should select the single surface first and
then, select the surfaces to be intersected with it. Otherwise only
the first two surfaces picked will be intersected. You can also intersect
groups. This intersects every surface in one group with every surface
in the other group.
-
Why is it that the hotkeys do not work when I am using the
OGL version on a SGI/Sun?
- Add the following line to your .Xdefaults file located in your home directory:
*glxarea.traversalOn: TRUE
- For Linux machines, be sure the .Xresources file is located in your home directory.
It should be the same as the .Xdefaults file.
-
How do I know which version of SolidMesh I am using?
- The version information is printed in the beginning of the sm xterm window.
-
Why is it that I am unable to rotate, translate, or zoom using the mouse?
- Be sure the NumLock key is not activated.
-
How do I export an IGES file from a 3rd party vendor so that it will read into
SolidMesh?
- IGES files exported from the following vendors have been successfully read into SolidMesh:
-
Why does my volume grid fail with the message *** surface that intersects BL found that is not planar *** when the surface is planar?
- The rebuild boundary condition is restricted to
PLANAR surfaces (or surfaces within xxx degrees
of being planar). However, this error message may still occur even if the surfaces are
planar when multiple planar surfaces are included in the same group.
For example, if there are two planar surfaces that form a 90 degree corner, individually the
surfaces are planar, but as a group they are not. This can be easily fixed
by placing the surfaces in separate groups.
-
What is the difference between the Source, Transparent, and
Transparent-Delete volume grid generation boundary conditions?
- The Source,
Transparent, and
Transparent-Delete
boundary conditions are all used to
refine the volume grid. The differences among the three are whether or not
the input surfaces are retained in the final volume grid and how they effect
boundary-layer growth.
A Source and a Transparent-Delete surface do not leave any embedded faces in the volume grid, i.e. the surface mesh for the Source surface and Transparent-Delete surface is NOT retained in the volume grid. The input surface mesh for Transparent surface is retained in the volume grid as an embedded surface.
A Source will NOT impede the boundary-layer growth. Source points that interfere with the boundary-layer will not be inserted. Transparent and Transparent-Delete surfaces MAY impede the boundary-layer growth.
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