Hi Michael,

I was seeing if some variation of the Flow command could arrange a boat-load of nozzle objects on the revolved curved surface of a giant shower head, and to arrange them in a rigid fashion - aligned with the surface normal.
The example shown was done with Flow in Projection mode and Rigid activated.
As you can see, the more outer nozzle objects that are trying to project along a very steep angle are now arranged kinda "wonky" to say the least.

I can see some logic in how this might happen, but before I try a few other methods, such as my Flow on a revolved surface procedure or using the Arrange Gem command, would you be able to offer a solution or shed some light on this?

None the less, I didn't know until today that there was a "rigid" option for projection. Good to know, but this presents a slight challenge.


I provided a file so that you can get a better look:
http://www.mediafire.com/?3tlre2zc6y1qh
"Nozzle Placement 01.3dm"

Hi Mike - the "projective" version of flow works by actually sending out rays from the base plane and intersecting that ray with the target object.

That whole process doesn't really work very well if the target object curves away close to a 90 degree angle from the projection plane - you generally will need to avoid using projective mode if it would require that kind of really steep angle to project on to.

It's more for projecting your object on to a localized area of the target object, so it's more intended that the base plane should normally be smaller than the target object instead of such a large one like you've got here.

See here for an example:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4656.7

Then the other thing situation that you've got there that causes additional difficulty is that many of the rays that are coming out from the plane like near the corners of the plane are going to completely miss the target object instead of landing on it. It kind of tries to deal with that but both missed rays as well as steep angled rays will tend to make a kind of lumpy projection in those areas - you can actually probably have those kinds of things just as long as you don't also have objects being deformed right in the same neighboring area of the missed rays or steep angle spots which you do have in your case here.

For this case I'd suggest preparing a projection target that's a little different in shape from the actual head - well the inside portion would be the same shape but you want something that's larger and has a kind of "easing off" boundary instead of the true steep boundary, something like this:



The center part of that larger one can be the same profile as your real head, but cut it off where it comes to around 30 degrees of vertical and then make an eased out extension from there. Then you still will project on to the central area only but I think you'll get better behavior, let me know if that helps.

- Michael

Ahaaa...

Seems this was a good test of the limits to this type of flow!
Thanks for illuminating a mystery to me.



I tried it again using a standard Flow with a Revolved surface as a reference.
The "Rigid" option was activated and it did a pretty good job with matching the placement.
Though, this was an example. A shower head this extreme would get half the bathroom wet.

Yes, the above could have been done with a simple circular Array with objects originally positioned to point outward from the surface normal,
but you could also do oblong and strangely shaped target surfaces.

So, Flow Projection is best for quick logos, simple items and items that are small in real estate compared to the target surface.
Flow (standard) will warp the flow of the objects in reference of one surface to another.

Thanks, Michael!

Hi Mike,

> So, Flow Projection is best for quick logos, simple items and
> items that are small in real estate compared to the target surface.
> Flow (standard) will warp the flow of the objects in reference of
> one surface to another.

Yup, I think that's a good description!

Another way to say it might be that projective flow is used for applying something like a decal on to a small portion of an object, while regular flow is more about warping across the entire surface extent.

- Michael