Hi, I'm trying to devise an efficient, rapid, on-the-fly way of measuring volumes of surfaces.

The volume is about 30 feet long fore to aft. Its height is about 40' and the width... well, that varies with flare as the hull rises, and with distance from fore to aft, the width widens. I have capped off the ends with bulkheads. There is downard slope from fore to aft, and as their is some curvature running high to low as one works toward the after bulkhead, a single line connecting the fore to aft distance would not be accurate. In plan view, the test surface i drew in is like a V with the pointier end at the front. In section, the hull is a V, with, of course, the pointy end being the keel. In the model, on separate layers, i have frames in 1-foot increments to help create ruled surfaces that are fair, not merely fore-to-aft surfaces. This introduces enlargement of the file much more than just a simple flat surface, even of the same area.



My failed attempts so far include:

-- Stitching surfaces together to try to arrive at creating an enclosed volume (no, bounding box is not viable, not for a ship hull or irregular enclosed volume... or, i think it is not)

-- running a surface (cover surface made from lines) through the v-shaped volume, getting silhouette/surface-to-surface intersect, only to end up with some 111 little lines. Eventually after giving up on joining, i found by zooming in that two dinky little extensions of two lines caused acis errors. (It would be nice if ACIS or VC would actually highlight the offending geometry to help us weaker drafters quickly determine and troubleshoot these skill-deficiency based problems.)... On a lark, i found i could select all the lines and get the surface of the deck that would be one bounding surface of the tanks.

Is it at all possible to just tell ViaCAD (or VC Pro) here are the enclosing surfaces, here are the further sub-divided tankages... give me the volume?

It would be hella nice if i could just draw a line, end it with a "bulb" or point or arrow, and watch if "fire" to calculate the volume of the enclosed surface. And, i mean, i need this without separating existing, to-be-retained surfaces above. I gave up on one of the newer split surface tools because my large surfaces got broken down into thousands of little surfaces when i expected the inserted deck to just "split" the upper and lower geometry with the surface drawn in to touch all surface on the edges "level" within the hull.

I realize this is not a ship design program, but soooo many tools present offer so much potential. This could be a water tank or a septic tank in the ground or an attachment to a linkage where the centers and moments would be needed. I don't have the CPU power nor the RAM to create solids just for purposes of getting volumes from objects. I could SWEAR i read of or used a tool in VC to get volumes... QUICKLY, without creating and chopping up unnecessary geometry...

In a word No. You need to model solids in order to get a volume.;)

That is rather unfortunate. Suppose one is designing a special container, like the colonge/perfume bottle. Creating a solid and shelling it might be nice for determining the weight of the glass. But, the volume is also necessary for planning product sizing. Too much extra work has to go into getting that calculation. For large models, like water towers, or under ground gas tanks and such, a model could become unnecesarily huge or just time consuming.

Is this an ACIS/Spatial thing? If so, it is such a huge oversight they need to do something about it -- FAST.

Hmmm.. unless i'm doing something wrong, that ends up causing huge CPU consumption (because i'm drawing things that are 560' long, 66' wide, 80' high, with many fuel tanks and ballast tanks and other voids -- a ship, that is -- and). So, i have to make surfaces of the contorted-shaped boundaries, stitch the surfaces, then define a shell, then be sure to get the solid's volume before deleting it lest i want to end up redoing/undoing steps....

It's just from my perspective that it's trivial. VC does (and i assume other apps do) "firing" in all directions to obtain whether a volume is fully contained to do some assemblages, if i read correctly. It just seems that if an app can "find"/"determine" the tolerance or fit of parts, there is possibly a way to pseudo-solidify it and use geometry to aid the user.

(But, at least VC's moments/centers/volumes for solids is a helluva lot more sensibly set up than AutoCAD's. Every time i try to approach gathering informaiton form AutoCAD, it's a layout from hell, so to speak. )

Anyway, i bet if Tim/ViaCAD introduced this as a new feature (despite the desire of others that bugs be fixed before any new features be introduced), this could be something to distinguish VC from other apps (AutoCAD?, Inventor?, TurboCAD?) used as prototypes to bigger/more expensive apps. Just my opinion....

>>I'm trying to devise an efficient, rapid, on-the-fly way of measuring >>volumes of surfaces.

Something we used to do at Lockheed for aircraft design may also work for your ship design process.

1. Calculate the 2D cross sectional area at key fuselage stations (your bulkhead and frame locations). Create a spline in the top view where x = station, and y = area.

2. Drop a line down from the min/max locations to the y = 0 axis.

3. Close the curves with a line between your min/max. You should now have a closed set of curves.

4. Calculate the area of these four curves forming a closed region, this is your approximate volume.

The above was a draftsman's technique for calculating volumes before CAD in aircraft design. It was also used by designers creating aircraft from CAD surfaces who choose not to create watertight solids.


Tim