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OK, here's another tome... As Zumer indicated, i might be going around the world to get to the house next door...:o It's not easy to read this on-screen i concede. In an attempt to make reading easier, i used paragraph headers matching the images being discussed. Maybe it will be easier if you print it and then run colored rules between paragraphs...

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I've decided to show a more positive and more descriptive way to add to VC and VCP and Shark a feature that i think could be an immense time saver. It would be a tool that is potentially namable as "Mirror Extrude (a solid) About Modelspace or a User-Defined Centerline".

The suggested feature would not be dependent upon limitations in ACIS which expects planar lines if lines are closed. It should also avoid 1 or 2-rail sweep issues when 4 lines are pre-selected and then a sweep is attempted, resulting in only two lines sweeping but no solid being generated.

My suggestion avoids the necessity of creating over a dozen lines to obtain a solid, and it would create the solid in seconds rather than the multiple minutes normally likely. My suggestion need not be tied to only naval architecture modeling, but can be useful for jewelry, automotive, and any other model that has symmetrical features that need to be swept, but where the original lines involved are not planar. Moreover, the user would not need to draw constructions nor create an entire box.

I'll use my own drawing's screen snapshots to help visualize my suggestion.

IMAGE 001

In image 001, you see the model of my ship. It is some 560 feet long. Breaking it down into managable chunks will normally be mind and labor intensive since VC/VCP/Shark are not automated with scripts the way industrial-strength, $12,000 to $100,000 per-seat naval architecture apps are.

The red lines visible are waterlines, mostly in pairs to demarcate the upper and lower bounds of the deck plating thickness. (Generally, the thickness will be uniform for a given plating, though in each level or at various waterlines, the plating may be thicker than the plate above or below it. It depends on modeling analysis output or experience-driven constraints.) These red lines are only the starboard (right-hand) side selected.

IMAGE 002

In image 002, you see the mesh that is not really useful (in my scenarios?) for much except to have visual boundaries (at least they can be color-coded), or from which to draw vertex-intersecting lines/curves.


IMAGE 003

In image 003, you see an isometric view of the hull. The selected (red) lines on the port (left) side are going to be hidden, but first, let's look at the next image, image 004.


IMAGE 004

In image 004, you see the body plan view, or elevation of the bow to aft (front to back) view. The selected lines are the port (left) side, and these will be hidden in subsequent images. They can be hidden because the notional "Mirror Extrude About Modelspace or a User-Defined Centerline" tool would not need these lines. Hiding them removes a lot of would-be clutter and tedium, and reduce stress or anxiety on the user.

The non-horizontal lines visible are Stations. These stations are paired lines, paired to demarcate plate thickness of the watertight transverse bulkheads in the hull (watertight regarding real-world weld-provided watertightness, not watertightness in the 3D modeling world explanation). They will be more apparent in a following image. Not shown here or in most of the other views is a solid that is the WT TVBHD. But, it is visible in Image 001.

(These paired lines are generated in Delftship for greater fidelity or faithfulness to the fairing process done in Delftship. VC/VCP/Shark cannot easily be used to create any offset lines for station or WT TVBHD because we users cannot select the mesh to cast the line against and later use that surface. After trial and error, i decided to create plate thicknesses in Delftship and not in VC/VCP. Again, the following tools cannot select the mesh:

-- Project Curve Surface tool

-- Surface/Surface Intersect

-- Curve/Surface Intersect

-- Silhouette Curve

Therefore, any surfaces that would perfectly intersect with the mesh and make for perfectly-shaped WT TVBHDs is not to be enjoyed unless each mesh is first broken down and re-joined as surfaces (or some external mesh-to-surface conversion tool is used, requiring the user to learn other tools and possibly fragmenting or fraying the user's devotion to VC/VCP/Shark). But, converting the object type to surfaces from meshes and then rejoining these surfaces further complicates downstream work (say, editing related to trimming deck surfaces or cutting holes in the hull for for overboard discharges or ports or other access point when the expanse of plating cut is not large enough, or when two adjacent surfaces need to be cut up). In such cases, the previously-joined surface has to again be broken converted to facets and then rejoined. This can become messy and disruptive to work that might have relied on that surface not being changed or edited. It could result in a face that is no longer true to or not identical to what is was before. This is a strong argument for having the mesh accessible in VC/VCP/Shark as a normal VCP surface, without the user needlessly struggling with Booleans and so on to get what is already there but not in the user-friendly object type.

IMAGE 005

In image 005, the aforementioned stations are quite visible. Also visible is a deck i created in an earlier session than these screenshots. I use the line trim (or also the region trim) tool(s) to break and remove the gray lines shown. I right-select the four lines and then select the region to be discarded. As you can more easily see in images 001 and 002 and 003, the WT TVBHD boundaries dictate where the plating is cut for each deck. Previously, i created at each waterline a pair of horizontal surfaces.

(This involved extra work of creating numerous immediately needed and subsequently needed layers to declutter the view and to avoid many instances of hide/show-all/undo hide and so on. With my tool suggestion, some aspects of this will be eliminated, namely creation of the deck plating construction surfaces. But, with the deck plating surfaces needed, each WT TVBHD is used along with the surface-to-surface intersection tool. I then had to cut each waterline line at intersections of the waterline and the s-to-s lines created by the intersection tool. Again, this is a lot of extra line work created out of the need to have boundaries for the deck plating in order to create 6 surfaces which would be stitched to make the solid that is the deck plating.)

In several cases, the trimmed/cut waterlines did not accurately intersect the stations. I am not certain that this is a Delftship problem in exporting the DXF 3D Polylines. I am concerned that it may be VCP's reading of the lines and approximating. But, it may be the version of DXF file used by Delftship. In any case, this situation would lead to the suggestion to create excess material and just trim it off. But, my tool idea would avoid that -- as long as we assume and accept that the cut-line gaps involved are sub-millimeter and irrelevant for modeling at my skill level and for non-real-world construction presentation.

IMAGE 006

In image 006, you see the result of (depending on one's skill or proficiency) of maybe an hour worth of trial and error, zooming, panning, and rechecking. And that is just for ONE section in the hull. There are 13 more. Other models might be larger hulls or more involved local areas.

(If an external FEA or FEM tool suggested raising or lowering the deck, i would have to go into Delftship and edit them and then re-export them. Arguably, i could just do this in VCP, but again, the perfectly-exported mesh is surface-a-non-grata. I created one-foot interval stations and then created surfaces between each interval of station, but that creates problems mentioned above in the Image 005 paragraph. I later created stations spanning 3, 4, 5, and 6 foot intervals of stations. Depending on where the stations are in the ship, these surfaces will be easy draws or longer ones. In many cases these tediously-inserted recreated surfaces are not faithfully smooth like the imported mesh. If they are used in renders, it would immediately become clear that all sorts of waviness in the model exists. Depending on the observer (say, a design competition judge), this could be an immediate and irrevocable, irrecoverable turnoff. )

IMAGE 007

NOW WE ARE STARTING TO GET INTO THE **MEAT** OF MY SUGGESTION (see following post)